WO2001059461A2

WO2001059461A2 - Diagnosis or prediction of headache

Info

Publication number: WO2001059461A2
Application number: PCT/GB2001/000589
Authority: WO
Inventors: Jayne Elizabeth Ellis; Laurence John Aspinall; Paul Henry Charles Mundill
Original assignee: Unilever Plc; Unilever Nv; Hindustan Lever Limited
Priority date: 2000-02-14
Filing date: 2001-02-14
Publication date: 2001-08-16
Also published as: AU2001232098A1; WO2001059461A3

Abstract

Disclosed is a method of predicting the onset of a period of maximum probability of occurrence of headache (other than a cluster headache) in a human subject, the method comprising the steps of: a) making a first measurement of the concentration of one or more analytes in a sample of urine from the subject at one or more time points to establish a reference value for the analyte concentration; and b) making a second measurement of the concentration of said analyte(s) in a sample of urine from the subject at one or more later time points; wherein the concentration of said analyte undergoes a characteristic change relative to the reference value, detection of said characteristic change being indicative of the onset of the period of maximum probability of occurrence of headache in the subject.

Description

Title: Improvements in or Relating to Diagnosis or Prediction of Headache

Field of the Invention

This invention relates to a method of diagnosing headache, especially menstrual headache, a method of predicting onset of headache, a method of preventing or reducing the severity of headache, and kits and apparatus of use in performing said methods.

Background of the Invention

Headache is extremely widespread and virtually all people experience some form of headache at some time. However, some headaches can be so severe as to be extremely debilitating, or else occur repeatedly so as to represent a significant healthcare problem and a cause of lost working hours. Several types of headache are recognised (distinguished mainly on the presumed cause, but also on the characteristics of the headache and any associated symptoms), including:

a) Tension Headache

Tension headache (with or without underlying depression) is the most common and accounts for more than 75% of all headaches. The pain is usually of mild to moderate intensity and is usually bilateral, although it may be unilateral and may affect any part of the head. More severe forms often involve the back of the head, neck and shoulders. Unlike migraine, tension-type headache is not accompanied by nausea, vomiting, photophobia or phonophobia and is usually not exacerbated by movement. The headache may persist for minutes to days. Neck stiffness or tenderness may accompany the headaches, but many patients show few or no signs of muscle tension.

b) Cluster Headache

Cluster headaches occur almost exclusively in men who smoke or drink heavily. Cluster headache is characterised by severe unilateral pain usually located in or around the eye. The pain is often described as "boring" and of unbearable intensity. The attacks are relatively short, 15 minutes to 3 hours, and tend to recur in "clusters" several times a day or the same time each day for several days, and are therefore, to some extent, predictable in advance of their occurrence. Attacks often come on during the night. Cluster headaches are quite distinct from the other types of headache described herein.

c) Rebound Headache

Occasionally, chronic headache may result from headache treatments (medication misuse headache): initial relief of pain by the treatment is followed by rebound headache, which can lead to patients taking the medication every day. This can occur with ergotamine, with an opioid alone or in combination with a simple analgesic, or with a 5-HT, agonist.

Patients with rebound headache usually improve when the drug is stopped, although symptoms may worsen temporarily. The exact cause of rebound headache is not understood.

d) Migraine

Migraine is thought to be the second most common cause of headache.

Migraine is an episodic condition with complete freedom from symptoms between attacks. The condition has two main forms. One type, migraine without aura (previously called "common migraine") affects about 75% of migraine sufferers: it is characterised by headache which can be severe and is typically unilateral, pulsating, and often accompanied by nausea, photophobia or phonophobia. Symptoms last 4-72 hours. With the second type, migraine with aura (previously called "classic migraine") which affects about 25% of migraine sufferers, the attacks are preceded by neurological symptoms such as visual disturbance or numbness.

The cause of migraine headaches is not understood, although factors (triggers) reported to provoke attacks in some patients include stress, alcohol, bright lights, hunger, or consumption of particular foods such as chocolate or cheese. Headaches in general, and migraine headaches in particular, are associated (by anecdotal evidence) with the menstrual cycle, and such headaches and migraines may be referred to as "menstrual headache" and "menstrual migraine" respectively. For present purposes, the term "menstrual headache" is understood to encompass all forms of menstrual headache, including menstrual migrame. A menstrual headache can be defined for present purposes as a headache (which, in general, can occur at any stage of the menstrual cycle) typically, but not necessarily, near the end of the cycle, and is caused by and/or associated with a change in the concentration of one or more analytes (especially hormones).

"Menstrual migraine" can be defined as a migraine that occurs within days -3 to +3 of the menstrual cycle (day 1 being the first day of bleeding in the new cycle) and at no other time during the cycle. "Menstrual associated migraine" may be defined as a migraine which may occur at any time during the menstrual cycle but wherein typically at least 50 % of all migraine episodes occur within days -3 to +3 of the menstrual cycle. Menstrual migraine and menstrual associated migraine are both understood to be caused by and/or associated with a change in the concentration of one or more analytes (especially hormones). (It should be borne in mind that some women suffer from both migraines which are caused by and/or associated with hormonal concentration changes [such as menstrual migraine and menstrual associated migraine] and from other migraines which have no hormonal association and so may occur at any time during the menstrual cycle, and the incidence of such non-hormonally associated migraines may often disguise or conceal the presence of hormonally associated migraines occurring more frequently at particular points in the menstrual cycle.)

Drugs are available which can be used for prophylaxis, so as to reduce the severity and/or frequency of menstrual headache attacks. Such prophylactic drugs include beta-biockers (e.g. propranolol, atenolol, metoprolol, timolol and nadolol) and 5-HT antagonists (such as Pizotifen). (For a review, see Drug and Therapeutics Bulletin 1998 36, 41-44). However, overuse or misuse of prophylactic drugs can cause unwanted side effects, including rebound headache, so timing of administration of such drugs is crucial. Unfortunately, at present there is no method of reliably predicting the onset of a migraine headache for any particular patient.

A lot of studies have been published concerning possible relationships between the levels of various hormones and susceptibility to headaches. For example, Nagel-Leiby et al, (1990 Cephalalgia 10, 147-151) investigated the plasma concentrations of oestradiol, total oestrogens and progesterone in three groups of women (normal control subjects; subjects reporting migraine without aura; and subjects reporting migraine with aura) at two different points in the menstrual cycle: the onset of menses and immediately prior to ovulation. They found "a significant rise in plasma oestradiol levels prior to ovulation only in migraine patients with aura" and a "near significant elevation in total oestrogens prior to ovulation for the same patients" . They found no differences between the three groups in the hormone levels at the onset of menses which finding "corroborated a previous report of normal levels of total oestrogen in migraine patients during the early follicular phase. In addition the present results corroborate a previous report of normal total oestrogen levels in migraine patients without aura at both ovulation and menses onset". The authors concluded that "oestradiol levels may be an important common factor that underlies the differing clinical expressions of the migraine disorder" (i.e. that oestradiol levels influenced the symptoms associated with the migraine attack; namely presence or absence of aura). The authors did not indicate or suggest that oestradiol levels might be used to predict the onset of a migraine attack.

Brun et al, (1995 Cephalalgia 15, 136-139) studied nocturnal melatonin excretion (in urine) throughout one complete menstrual cycle in normal women and in a group of women reporting migraine without aura. However, they "were not able to find a correlation between ... time of headache and nocturnal melatonin excretion" , and therefore the disclosure of Brun et al does not suggest a method of predicting attacks of migraine without aura.

Elwan et al, 1991 J. Neurological Sciences 106, 75-81) investigated hormonal changes in patients with headache, in particular levels of follicle-stimulating hormone (FSH), LH, cortisol and prolactin, in serum and in cerebrospinal fluid (CSF), with a view to determining "whether any changes in these factors might contribute to, or aid diagnosis of, certain types of headache" . They found high levels of FSH in male and female patients suffering from migraine or chronic tension headaches. However, the serum and CSF samples were taken over a narrow time-scale (mid-luteal phase in women subjects) and so could not draw any conclusions as to levels of FSH and occurrence of headaches. Elwan et al thus neither disclose, discuss nor suggest that hormone levels could be used to predict the onset of headache episodes.

Summary of the Invention

In a first aspect the invention provides a method of predicting the onset of a period of maximum probability of occurrence of headache (other than a cluster headache) in a human subject, the method comprising the steps of:

a) making a first measurement of the concentration of one or more analytes in a sample of urine from the subject at one or more time points to establish a reference value for the analyte concentration; and

b) making a second measurement of the concentration of said analyte(s) in a sample of urine from the subject at one or more later time points wherein the concentration of said analyte undergoes a characteristic change relative to the reference value, detection of said characteristic change being indicative of the onset of the period of maximum probability of occurrence of headache in the subject.

In particular the method is especially suitable for predicting the onset of maximum probability of occurrence of menstrual headache, and especially menstrual migraine or menstrual associated migraine, in a human female subject, where step (a) involves making a first measurement of the concentration of one or more analytes at one or more time points during a menstrual cycle, and step (b) involves making a second measurement of the concentration of said analyte(s) at one or more later time points during the same and/or a subsequent menstrual cycle.

The skilled reader will appreciate that the urine "concentration" of the chosen analyte or analytes need not be measured in absolute terms, although this can of course be done if desired. Generally, it will be sufficient to assay an analyte in a manner which yields a signal, (preferably convertible to numerical data), related to the actual concentration, so that such data can be compared with similar data obtained at a different phase in the cycle (and optionally with data obtained at the same or different phases in one or more preceding cycles) to determine whether or not a significant change in actual concentration has occurred. Accordingly, where the specification and claims below refer to the "concentration" of an analyte, this expression should be interpreted broadly.

In particular, in preferred embodiments, the invention involves the measurement of two or more different analytes, so as to obtain a ratio of the concentrations thereof. The inventors have _'found that such ratios are generally of greater predictive value than concentrations of individual analytes.

The analyte or analytes measured in the method may be any analyte which undergoes a characteristic change in absolute and/or relative concentration during the menstrual cycle. Generally, the most suitable analytes are hormones (especially steroid hormones, most especially steroid hormones present in urine) and/or their metabolites. Examples include the following: follicle stimulating hormone (FSH), Iuteinising hormone (LH), estradiol and metabolites thereof, and progestogens and metabolites thereof.

Relevant metabolites of estradiol suitable for analysis in the invention include the following: estrone-3-glucuronide (E3G), estradiol-3-glucuronide, estradiol-17-glucuronide, estriol-3- glucuronide, estriol-16-glucuronide and estrone-3 -sulphate (E3S). In general, E3G is the preferred analyte. Another particular analyte whose concentration may usefully be measured in accordance with the invention is pregnanediol-3-glucuronide (P3G).

In particular embodiments, it is desirable to measure the urinary concentration of E3G, either alone or together with a determination of the urinary concentration of FSH and/or P3G, so as to allow calculation of an E3G/FSH and/or an E3G/P3G ratio, respectively. By way of explanation, the inventors have found that the ratio of E3G to FSH has a peak value in the range of days -7 to -2 of the cycle (day 1 being the first day of bleeding), and statistical analysis showed that the mean day for peak E3G/FSH ratio was at -5 to -4, and thereafter the E3G/FSH ratio undergoes a characteristic sharp decline. The inventors have found that incidence of menstrual headache is highest at days -3 to +3 (with maximum headache occurrence at day-1 and day 1), such that the decline in E3G/FSH ratio from its peak value provides at least 24 hours' warning, typically about 48 hours' warning, of onset of the period of maximum probability of menstrual headache.

In another embodiment, a characteristic decrease in E3G/P3G ratio typically provides 24 hours' warning of onset of the period of maximum probability of headache. The inventors have derived an equation which allows the calculation of the probability of a headache occurring in a subject the next day. Details of the equation are provided in the accompanying examples.

In addition to measurement of the analyte or analytes, the characteristic change in concentration of which is indicative of the onset of the period of maximum probability of headache, the method of the invention may desirably involve measurement of the concentration of one or more further analytes (preferably further urinary analytes). In particular, for example, the method may involve measurement of analytes which provide information about the current phase of the menstrual cycle of the subject.

A preferred example is measurement of LH (if measurement of LH is not one of those analytes whose measurement is required to determine the onset of the period of maximum probability): measurement of LH can be used to detect the "LH surge" which precedes ovulation. Thus, in some preferred embodiments, E3G/FSH and/or E3G/P3G ratios are determined, which ratios undergo a characteristic change prior to onset of the period of maximum probability of headache, and in these embodiments LH may conveniently be a further analyte which is measured from time to time.

The number of time points at which analyte concentrations are measured (or the frequency of testing, in terms either of number of tests per cycle or in the number of days between tests) will tend to depend on the identity of the analyte being measured.

Equally, the characteristic concentration change may generally take place at around a particular phase of the subject's menstrual cycle. Accordingly, it may be desired to measure one or more analytes to provide information about the current phase of the subject's menstrual cycle (as explained above). Additionally, it will normally be advantageous to increase the frequency of analyte concentration measurements at or shortly before that phase of the cycle which is associated with the characteristic change indicating onset of maximum probability of headache occurring, so as to maximise the chance of detecting the characteristic change at the earliest opportunity (thereby providing the earliest possible warning to the subject) without imposing a rigorous testing regimen requiring daily testing throughout the cycle.

In one embodiment a testing regime as follows might, for example, be adopted. Analysis of levels of LH, P3G and E3G in urine may be performed a plurality of times (preferably daily) in the period spanning days 1 to 9 of a cycle (day 1 being the first day of bleeding), to establish reference values. Thereafter LH and (optionally) E3G values may be determined occasionally (e.g. every other day) until the LH surge is detected, following which E3G and P3G levels are measured during the luteal phase more especially in the late luteal phase (i.e. in the latter half of the luteal phase), either daily or at less frequent intervals.

It is preferred that the pattern of analyte analysis should be tailored to the individual. For example, by taking into account data from previous menstrual cycles in that individual, an automated monitoring apparatus can adjust the time points at which analyses are to be made, and can adjust calculations regarding the onset of maximum probability of headache.

Methods of sampling body fluids and making the necessary analyte concentration determinations are routine. In particular, in the unconnected fields of fertility monitoring and contraception, methods and apparatus for measuring, monitoring and recording the concentration of urinary analytes such as E3G and LH have been disclosed (see, for example, WO 95/01128; WO 94/04925; and EP 0656118), and such methods and apparatus are especially suitable to be adapted for use according to the present invention. In general, immunoassay-based techniques are preferred.

Typically the method of the invention predicts the onset of the period of maximum probability of occurrence of headache between 12 and 72 hours in advance of the commencement of the period of maximum probability of headache, preferably between 24 and 72 hours in advance of such commencement. The method of the invention is especially useful, and preferably applied, in situations where the subject has no other means of predicting the onset of the period of maximum probability of headache occurrence. For example, the method is especially suitable in predicting onset of migraine without aura (patients who suffer from migraine with aura generally experience the visual disturbances and other symptoms of the aura shortly before the headache commences and therefore have a limited warning period). Equally, a few women suffer from headaches, especially migraine headaches, which are very closely associated with a particular stage of the menstrual cycle (usually onset of menses, occasionally ovulation), and can therefore estimate approximately when a migraine attack is most likely to occur. It should, however, be noted that such women do not usually experience a migraine attack in every cycle, and therefore cannot predict whether a headache is likely in any particular menstrual cycle, which possibility is provided by the present invention.

The method of the first aspect of the invention, defined above, provides sufficient warning for the subject to take suitable steps to avoid, or at least moderate the severity of, a menstrual or other headache attack (e.g. by taking drugs such as analgesics; triptans; ergotamines; or consuming dietary supplements/herbal remedies such as magnesium salts; fish oils; or feverfew); or else identification of the maximum headache probability period can allow the subject to take care to avoid known triggers (e.g. cheese, chocolate, red wine) during this time.

Accordingly, in a second aspect the invention provides a method of preventing, or reducing the severity of, headache in a human subject, the method comprising the steps of (a) identifying the period of maximum headache probability, as defined above in the first aspect of the invention; and (b) administering a prophylactic and/or therapeutic agent to the subject before and/or during the period of maximum headache probability. The prophylactic/therapeutic agent may be any of those known to those skilled in the art and found effective in the subject. Desirably the agent will be administered before the subject develops a headache or any of the symptoms which may be associated therewith (e.g. aura, nausea etc). Alternatively, step (b) may comprise the step of avoiding known triggers (with or without administration of a prophylactic or therapeutic agent).

In a third aspect, the invention provides a method of predicting the onset of a period of maximum probability of occurrence of headache (other than a cluster headache) in a human subject, the method comprising the steps of:-

a) making a first measurement of the concentration of estradiol or a metabolite thereof and a first measurement of the concentration of a further analyte in a sample of body fluid from the subject at one or more time points to establish a reference value for the ratio of the concentration of estradiol or metabolite thereof to the concentration of the further analyte; and

b) making a second measurement of the concentration of estradiol or a metabolite thereof and the further analyte in a sample of body fluid from the subject at one or more later time points; wherein the ratio of the concentration of estradiol or metabolite thereof to the concentration of the further analyte undergoes a characteristic change relative to the reference value, detection of said characteristic change being indicative of the onset of the period of maximum probability of occurrence of headache in the subject.

The body fluid may be urine, blood or any other suitable body fluid. Suitable metabolites of estradiol include estrone, estriol, and the -3 or -17 glucuronides (as appropriate) of estradiol, estrone and estriol, although it should be noted that the glucuronide metabolites rapidly accumulate in urine, and so where the body fluid sample comprises blood, serum or plasma, it will not be appropriate to measure the concentration of a glucuronide metabolite.

In the method of the third aspect of the invention, the further analyte preferably comprises FSH or progestogen or a metabolite thereof (such as pregnanediol, pregnanediol-3- glucuronide etc.). Generally, the preferred features of the method of the third aspect of the invention are the same as those preferred in the method of the first aspect.

It can be difficult to diagnose the cause of recurrent headaches, as there are many factors which could be implicated. The present invention provides a method by which recurrent headache in a subject can be shown to be associated with the concentration of an analyte in the subject, and especially associated with the concentration of one or more hormones (e.g. menstrual headache).

Thus, in a fourth aspect the invention provides a method of diagnosing the occurrence of a headache in a human subject as being associated with a characteristic change in the concentration of one or more analytes in the subject,

(a) measuring the concentration of the analyte(s) in a sample of urine from the subject at a plurality of time points;

(b) noting the occurrence of the characteristic change in concentration of the analyte(s):

(c) recording any instances of headache in the subject; and (d) identifying a correlation if any, between the occurrence of the characteristic change in concentration of the analyte(s) and instances of headache in the subject.

Preferably the diagnostic method may be applied to diagnose the occurrence of menstrual headache in a human female subject as being associated with a characteristic change in the concentration of one or more hormone analytes (especially E3G and, optionally, P3G) involved in regulating the menstrual cycle.

Typically a statistical analysis may be applied to assist in the determination of the likely significance of any such co-incidence which is determined, although in some cases there will be a clear relationship (e.g. over 75% , or more typically over 85%, of headaches occurring in the identified period of maximum probability of menstrual headache). It will be appreciated that, in order to obtain statistically meaningful results, the diagnostic method will normally need to be continued over a plurality of menstrual cycles (preferably at least three such cycles), depending on the frequency of headaches experienced by the subject.

In a fifth aspect the invention provides a method of calculating the likelihood of a subject experiencing a headache on the next day, the likelihood being calculated according to the equation:

Probability of headache occurring next day = subject effect - x log [E3G] + y log [P3G]; where the subject effect is a measure of the inherent frequency of headache occurrence in the individual, and x and y are the regression coefficients for [E3G] and [P3G] respectively.

The method of the fifth aspect of the invention is especially suitable for predicting the probability of a menstrual headache occurring the next day in a human female subject, and especially in the period spanning days -3 to +3 (inclusive) of the menstrual cycle (with day 1 as the first day of bleeding). The invention further provides electronic means for use in identifying the onset of the period of maximum probability of a headache (especialy menstrual headache) in a human subject, the electronic means being programmed to process analyte concentration test data obtained by testing of samples of urine from the subject at a first and one or more later time points and to identify from said processing an analyte concentration change indicative of the onset of the period of maximum probability of a headache.

Conveniently the electronic means is incorporated in a recording device having recording means to record the results of the analyte concentration tests, and display means to display information concerning the probability of a headache occurring in an individual subject whose analyte concentration has been tested. Typically the recording device is provided with means to measure the result of an analyte concentration test conducted using a testing device which is presented to the recording device. The testing device is conveniently a urinary analyte testing dip-stick type device, of the type known from the prior art (e.g. GB 2204398, EP 0383619).

The display means of the recording device will preferably be adapted so as to display a warning signal (e.g. a red light) to the subject when the electronic means detects the onset of the period of maximum probability of headache.

If desired, the apparatus may be designed such that a warning signal (e.g. red light) is shown during every menstrual cycle at the beginning of the period of maximum probability of headache occurrence. Alternatively, if desired, the apparatus can be arranged such that only a characteristic change (in analyte concentration) above a certain threshold value will trigger display of a warning signal, such that there may be cycles when a warning signal is not displayed.

The electronic means, and the recording device incorporating the electronic means, represent further aspects of the invention. Elecronic means and a recording device which may suitably be adapted for use in these aspects of the invention are disclosed, for example, in WO 94/04924, WO 94/04295, WO 94/04296 and WO 96/09553. In a further aspect, the invention provides a test kit for providing information on the probability of a headache (particularly a menstrual headache) occurring in a human female subject, the kit comprising: one or more testing devices for determining the concentration of a relevant analyte in a sample of urine from the subject, which analyte concentration undergoes a characteristic change indicative of the onset of the period of maximum probability of headache occurring; and electronic means programmed to process analyte concentration test data from the one or more testing devices, so as to detect the characteristic change.

The invention will now be further described by way of illustrative examples and with reference to the accompanying drawings, in which:

Figure 1 is a bar chart showing the incidence of headache in sample groups of women volunteers;

Figure 2 is a graph showing headache prevalence (left hand axis) or hormone level or ratio (right hand axis) against day of cycle;

Figures 3 A and 3B are graphs of log [E3G] against log [P3G], for days when 24 hours later subjects reported headache (crosses) or no headache (circles); and

Figures 4A and 4B are graphs of probability of headache against time (day of trial) for two volunteer subjects.

Examples

Example 1

The inventors conducted a study involving a group of 112 women volunteers. This sample was sub-divided into three groups: group 1 contained fertile women in the age range 30- 40, having normal menstrual cycles; groups 2 and 3 contained women who were pre- and perimenopausal respectively.

The women were monitored for a period of 6 months. Within this time, the volunteers were asked to keep a record of their cycles, and of the days of the cycle on which they experienced headache (day 1 being the first day of bleeding for each cycle). In addition, the inventors arranged for analysis of daily urine samples from the volunteers, measuring concentration of four urinary analytes: E3G, FSH, LH and P3G.

Automated time-resolved fluorescence immunoassay was used for the measurement of urinary estrone-3 -glucuronide (E3G), pregnanediol-3-alpha-glucuronide (P3G), follicle stimulating hormone (FSH) and luteinizing hormone (LH), in samples of early morning urine from the volunteer subjects. The whole procedure was carried out using the AutoDELFIA 1235 automatic immunoassay system.

The method for measurement of E3G and P3G involved a competitive immunoassay using a labelled (Wallac Europium chelate (eg. E3G-Eu3 +)) antigen. Rabbit anti-mouse plates (Wallac) were washed with wash buffer (Wallac reagent 1244-114), then lOOμl of standard, QC or urine were added to the coated wells. (For the assay, three sets of "QC" references were used ("high", "medium" and "low"). For example, for assay of E3G, the QC values used were 2.8 ng/ml (low), 59.3 ng/ml (medium) and 152.6 ng/ml (low), 59.3 ng/ml (medium) and 152.6 ng/ml (high). In each assay, each QC value was testedin triplicate, acting as checks on sensitivity and precision. Acceptable ranges for the different QC values had been calculated previously by retrospective analysis of 100 plates (using carefully-prepared "gold" standards), and microtitre plates giving results for the QC values outside this acceptable range were rejected and the samples re-analysed on a fresh plate). To this, lOOμl of assay buffer (Wallac 1244-111) containing mouse antibody of the desired specificity was added to the plate, which was then incubated (with shaking) for 30 minutes. The steroid-Europium conjugate was added (lOOμl in assay buffer) to the plate. After incubation for 30min on a shaker at room temperature, the plate was washed and 200μl of enhancement solution added to each well. Concentrations were determined from standard curves using the AutoDELFIA fluorimeter. The data were processed by the AutoDELFIA Multicalc programme. This method demonstrated appropriate sensitivity and precision across the relevant working ranges for each analyte.

The method for LH and FSH measurement involved a sandwich assay. Microtitre plates were precoated with anti-LH or anti-FSH monoclonal antibody (coating carried out by Wallac and plates supplied dry) and loaded into the AutoDELFIA. Standard, QC or urine samples were dispensed into wells of the plate. To this, 200/χl of Europium-labelled

(Eu3+) monoclonal antibody conjugate was added to each well (appropriately diluted), and incubated (with shaking) for 2 hours. The plate was washed thoroughly in wash buffer (Wallac) and enhancement solution (Wallac 1244-105) was added to each well, the plate shaken for 5 min, and the counts read. Concentration values were calculated from the standard curve in the AutoDELFIA Multicalc programme. The reader is referred to Saketos et al, 1994 (Clinical Chemistry 40, 749-753) for a detailed description of the principles of the assay.

The findings of this preliminary study are shown in Figures 1 and 2.

Figure 1 is a bar chart of the cumulative data from the study, showing the percentage of the volunteers who reported experiencing a headache on a particular day of their menstrual cycle. In this and the following example, for statistical/mathematical reasons, Day 1 (first day of bleeding) was treated as "Day 0", and "Day 1" equated to the second day of the cycle. The data show that maximum incidence of headache was reported in the range day - 2 to +3 of the cycle but that significant numbers of headaches were reported at other times in the cycle.

Figure 2 is a graph showing (on the left hand axis) the percentage of women reporting a headache on a particular day of their cycle (bar chart) for days -7 to +7. The right hand axis shows the level of E3G (μg/ml square symbols) or the ratio of E3G to FSH (circle symbols). It can be seen from Figure 2 that the incidence of headache is associated with a general decline in level of E3G. Accordingly, a declining level of E3G could be used as an indication as to the onset of the period of maximum risk of menstrual headache. More particularly, the inventors found that the absolute level of E3G had some predictive value.

However, a much stronger, clearer indication is provided by the E3G/FSH ratio. This ratio peaks at days -5 to -4 and thereafter falls very sharply. This peak and subsequent decline occurs approximately one or two days before the maximum headache probability period, and is far easier to detect than the comparatively gentle, steady decline in the level of E3G alone. Accordingly, analysis of urinary E3G/FSH ratio provides one preferred embodiment of a method of predicting the onset of the maximum headache probability period in accordance with the invention: detection of a peak in E3G/FSH ratio (indicated by a sudden fall in the ratio) signals onset of a period of maximum risk for headache occurrence about 48 hours later.

Example 2

Following the success of the trial outlined in Example 1 , it was decided to explore the possibility of predicting the likelihood of a headache occurring within 24 hours, based on analysis of hormone concentrations in early morning urine. For this analysis, a subgroup of subjects (out of the original 112) with at least 3 headaches per cycle were selected. Cycle starts were defined by the first day of at least two successive bleeds. As before, for statistical/mathematical reasons, the first day of the cycle was denoted as Day 0, rather than the conventional notation of Day 1.

Analysis

Exploratory plots and statistical analysis established that statistically significant (pO.OOl) prediction equations can be constructed.

The Glimmix macro "generalised linear mixed models" (Little et al 1996 "SAS system for mixed models", p423-460 SAS Institute Publ., Gary. NC, USA) was used to fit a model with: Response = headache (0,1 data)

Predictors = Subject effect, log (E3G on previous day), log (P3G on previous day). The "subject effect" takes into account the difference between different individuals in the tendency to have headaches - since individuals for the analysis were selected to have at least 3 headaches per cycle, [taking a cycle as 30 days], this represents a base subject effect of 0:1 (i.e. odds of 3/30), which may be higher or lower for particular individuals. More generally, the subject effect would be based on the average value for the population at large, for the first time a person used a monitoring system. Thereafter, the value can be adjusted for an individual user to take into account retrospective data collected in previous cycles. Eiror structure = Binomial for response, with Toeplitz 3-band structures for successive days within subjects.

From the data the following equation was derived: log (probability of headache) occurring the next day = Subject effect -0.442 log(E3G) + 0.251 log(P3G). The values -0.442 and +0.251 are the regression co-efficients for E3G and P3G respectively (based on the data obtained from subset of 21 volunteers).

The error structure was chosen to allow for correlation between 'headaches on the next day' are more likely following days with low E3G and high P3G. Examples for this are shown in Figures 3A, 3B, which are plots of data obtained from two representative subjects. Days with no headaches reported are shown by circles; days on which headaches were reported are shown by a cross. These are plotted against measures of the concentration of E3G and P3G in the subject measured 24 hours previously.

Using the equation defined above, the inventors prepared graphs (Figures 4A,B) of the calculated probability (odds) of headache occurring, against time, for each of the volunteers from whom the data in Figures 3A,B were obtained. In Figures 4A and 4B, the probability (odds) of headache is shown by the jagged line for days 60-250 or 80-280 of the trial respectively. The long vertical lines indicate those days on which the volunteers experienced a headache. The short vertical lines indicate days on which bleeding was experienced (and hence indicate the start of each cycle). It is clear that the equation has useful predictive value, as the graphs show that headaches almost only occurred when the calculated probability of a headache was relatively high. This held good, regardless of the stage of the cycle - see, for example, the headaches experienced by the subject in Figure 4A between days 140 and 150 of the trial. This method may be used not only for prediction of likelihood of headache/migraine on the next day, but also for the diagnosis of hormonal-related headache or migraines. The method for this would be to collect hormone information over a preset number of cycles, collecting information on headache/migraine incidence. The data analysis by the above method would reveal a significant association between hormones and headache. A relevant treatment could then be offered, such as estradiol administration, HRT etc.

Data from a slightly larger subgroup (27 subjects) were used to obtain regression coefficients and Z ratios (Z ratio is the regression coefficient ÷ standard error) for each of the analytes E3G, FSH, LH and P3G, either in isolation or in various combinations, as predictors of headache occurring the next day. The results are shown in Table 1 below, which show the significance for each regression coefficient after allowing for the other terms in the model. All regressors were of the form: log (concentration).

From the table it can be observed that neither FSH or P3G concentration, in isolation, have a particularly high predictive value. LH concentration, in isolation, does have a moderate predictive value. E3G concentration however has by far the best predictive value. Of the various combinations, the data suggest that analysis of the concentration of E3G and P3G in combination provides the greatest predictive effect: additional analysis of LH and/or FSH does not increase the size of the Z ratio.

From the data analysed, the equation derived for determining the probability of a headache occurring the next day (log [headache]) for any particular individual was: log [headache] = subject effect - 0.40 log (E3G) + 0.23 log (P3G). (It should be noted that different methods of assaying E3G and P3G concentrations, [e.g. using different antibodies in the immunoassay] will give different values for the absolute concentration of these analytes, and the regression coefficients may therefore alter accordingly.)

This can be rewritten as log [headache] = subject effect - 0.40 log (E3G/P3G) - 0.17 log (P3G), which illustrates that the synergy observed by analysing both E3G and P3G concentrations is not simply due to "smoothing" obtained by using concentration ratios (which provide an "internal reference" for the analyte assays). Both E3G P3G and P3G tend to have unimodal concentration profiles within a single menstrual cycle, with minima occurring around menstruation, corresponding to the period of maximum probability of headache.

For the subgroup analysed in this example, the mean value of the subject effect was -0.91, and the range of values was from -1.85 to + 0.48.

Table 1: Combinations of previous day analytes for predicting headache:

Regression coefficient (z ratio)

The Z ratio provides a test of statistical significance: the greater the Z ratio (positive or negative), the greater the significance. Z ratio values (+/-) of 1.96, 2.58, 3.29 and 3.89 correspond to confidence intervals of 95%, 99%, 99.9%> and 99.99%) respectively. Example 3

Example of a monitoring method for headache prediction

There are a number of ways of achieving this; the following is presented for purposes of illustration only and utilises monitoring of the urinary analytes E3G (estrone-3-glucuronide), LH (luteinizing hormone) and P3G (preganediol-3 -glucuronide). Metabolites that could also be assayed for this purpose include estradiol metabolites (estradiol-3 -glucuronide, estradiol- 17-glucuronide, estriol-3 -glucuronide, estriol- 16-glucuronide) and estrone-3 sulphate (principally for salivary assay). Generally the most suitable analytes are hormones and their metabolites. Levels of the neurotransmitter, serotonin, are also thought by the inventors to be predictive of migraine and headache. Examples of alternative body fluids, which are relatively accessible, are saliva, crevicular fluid, sweat, sebum, tears, blood and vaginal fluid.

Testing of urinary hormones for LH and E3G (+/- P3G) is carried out over the interval spanning days 1 to 9 inclusive, of the current cycle. The cycle start is defined as the first bleed day. This testing establishes a reference concentration value for the current cycle. Subsequent testing is compared to this reference value or signal, and is recommended to commence on day 9 of the current cycle and continued on at least a daily basis until a significantly elevated concentration is detected. Continued daily early morning urine testing will detect the subsequent LH surge and indicate ovulation. Following detection of the LH surge, a testing protocol of E3G and P3G is commenced where tests are carried out at intervals (typically, daily) over the luteal phase, which may be between 10 to 17 days for a normal luteal phase (see Lenton et al, 1984 Br. J. Obs. Gynae. 91, 685-689). Increased probability of headache is detected by one of the proposed methods (E3G/P3G equation. E3G slope + P3G, E3G alone, E3G/FSH). This is indicated by the monitor as high risk for headache or migraine. This could be combined to time treatment for migraine or headache, which could be by a number of different methods (e.g. analgesics, triptans, oestradiol, ergotamines). It offers significant benefit where overuse of prophylactics, when treatment is not timed, is known to lead to rebound headaches. In addition, the determination of high risk could be used to modify dietary intake, such as the avoidance of foods known to trigger headache/ migraine (such as cheese, red wine, chocolate etc.) or alleviate migraine/ headache (such as feverfew, tryptophan-enriched products, magnesium, fish oils, phytoestrogens).

Claims

1. A method of predicting the onset of a period of maximum probability of occurrence of headache (other than a cluster headache) in a human subject, the method comprising the steps of:

b) making a second measurement of the concentration of said analyte(s) in a sample of urine from the subject at one or more later time points; wherein the concentration of said analyte undergoes a characteristic change relative to the reference value, detection of said characteristic change being indicative of the onset of the period of maximum probability of occurrence of headache in the subject.

2. A method of predicting onset of a period of maximum probability of occurrence of menstrual headache in a human female subject, according to claim 1, wherein step (a) comprises making a first measurement of one or more urinary analytes at one or more time points during a menstrual cycle, and step (b) comprises making a second measurement of said analyte(s) at one or more later time points during the same and/or a subsequent menstrual cycle.

3. A method according to claim 1 or 2, comprising measurement of the concentration of at least two analytes, so as to allow determination of the ratio of concentrations of the two analytes at one or more time points.

4. A method of predicting the onset of a period of maximum probability of occurrence of headache (other than a cluster headache) in a human subject, the method comprising the steps of:- c) making a first measurement of the concentration of estradiol or a metabolite thereof and a first measurement of the concentration of a further analyte in a sample of body fluid from the subject at one or more time points to establish a reference value for the ratio of the concentration of estradiol or metabolite thereof to the concentration of the further analyte; and

d) making a second measurement of the concentration of estradiol or a metabolite thereof and the further analyte in a sample of body fluid from the subject at one or more later time points; wherein the ratio of the concentration of estradiol or metabolite thereof to the concentration of the further analyte undergoes a characteristic change relative to the reference value, detection of said characteristic change being indicative of the onset of the period of maximum probability of occurrence of headache in the subject.

5. A method according to any one of the preceding claims, for predicting the onset of the period of maximum probability of occurrence of a menstrual migraine or menstrual associated migraine in a human female subject.

6. A method according to any one of the preceding claims, comprising measurement of the concentration of one or more hormone analytes or further analytes.

7. A method according to any one of the preceding claims, comprising measurement of the concentration of one or more steroid hormone analytes or further analytes.

8. A method according to any one of the preceding claims, comprising measurement of the concentration of one or more analytes or further analytes selected from the group consisting of: follicle stimulating hormone (FSH); Iuteinising hormone (LH); and progestogen and metabolites thereof.

9. A method according to claim 1 or any preceding claim dependent thereon, comprising measurement of the concentration of an analyte selected from the group consisting of estradiol and the following metabolites thereof: estrone-3 -glucuronide (E3G); estradiol- 3 -glucuronide; estradiol- 17-glucuronide; and estriol-3 -glucuronide.

10. A method according to any one of the preceding claims, comprising measurement of the concentration of pregnanediol-3-glucuronide (P3G).

11. A method according to any one of the preceding claims, comprising determination of the ratio of E3G and P3G concentrations.

12. A method according to claim 4, wherein the body fluid is selected from the group consisting of: blood; saliva; crevicular fluid; sweat; sebum; tears; vaginal fluid; and urine.

13. A method according to any one of the preceding claims, comprising measurement of the concentration of one or more analytes to provide information about the current phase of the menstrual cycle of the subject.

14. A method according to claim 13, comprising measurement of the concentration of LH and detection of the LH surge preceding ovulation.

15. A method according to any one of the preceding claims, wherein measurements of the concentration of one or more analytes made during one or more previous menstrual cycles are used to assist detection of the characteristic change and/or are used to assist selection of time points at which to make measurements in the current menstrual cycle.

16. A method of calculating the likelihood of a subject experiencing a headache on the next day, the likelihood being calculated according to the equation:

17. A method according to claim 16 where x = 0.40 +/- 0.05.

18. A method according to claim 16 or 17, where y = 0.23 +/- 0.03.

19. A method according to any one of claims 16-18, for predicting the likelihood of a menstrual headache occurring the next day in a human female subject in the period spanning days -3 to +3 (inclusive) of the menstrual cycle, with day 1 as the first day of bleeding.

20. A method of preventing, or reducing the severity of, headache (other than a cluster headache) in a human subject, comprising the steps of (a) identifying the onset of a period of maximum probability of occurrence of headache in the subject by performing the method of any one of claims 1-15; and (b) administering before or during the identified period of maximum probability of occurrence of headache a prophylactic and/or therapeutic agent to the subject to prevent, or reduce the severity of, a headache.

21. A method of diagnosing the occurrence of a headache (other than a cluster headache) in a human subject as being associated with a characteristic change in the concentration of one or more analytes in the subject, the method comprising the steps of:

(b) noting the occurrence of the characteristic change in concentration of the analyte(s);

(c) recording any instances of headache in the subject; and

(d) identifying a correlation if any, between the occurrence of the characteristic change in concentration of the analyte(s) and instances of headache in the subject.

22. A method according to claim 21, which provides for the diagnosis of a menstrual headache in a human female subject as being associated with a characteristic change in the concentration of one or more hormone analytes involved in regulating the menstrual cycle.

23. A method according to claim 21 or 22, comprising measurement of the concentration of E3G and, optionally, P3G and/or FSH.

24. A method according to any one of claims 21-23, wherein the concentration measurements in step (a) are repeated for a plurality of menstrual cycles in the subject.

25. Electronic means for use in identifying the onset of the period of maximum probability of a headache in a human subject, the electronic means being programmed to process analyte concentration test data obtained by testing of samples of urine from the subject at a first and a second time point and to identify from said processing an analyte concentration change indicative of the onset of the period of maximum probability of a headache.

26. A recording device incorporating an electronic means in accordance with claim 25, and further comprising recording means to record the results of analyte concentration tests, and display means to display information concerning the probability of a headache occurring in an individual subject whose analyte concentration has been tested.

27. A test kit for providing information on the probability of a headache (particularly a menstrual headache) occurring in a human subject, the kit comprising: one or more testing devices for determining the concentration of a relevant analyte in a sample of urine from the subject, which analyte concentration undergoes a characteristic change indicative of the onset of the period of maximum probability of headache occurring; and electronic means programmed to process analyte concentration test data from the one or more testing devices, so as to detect the characteristic change.

28. A test kit according to claim 27 for use in the method of any one of cl aims 1-15.