EP2978367A1

EP2978367A1 - Method for measuring flushing and use for assessing treatments

Info

Publication number: EP2978367A1
Application number: EP14713135.3A
Authority: EP
Inventors: Laurent Petit; Anne-Sophie DUGARET
Original assignee: Galderma Research and Development SNC
Current assignee: Galderma Research and Development SNC
Priority date: 2013-03-29
Filing date: 2014-03-28
Publication date: 2016-02-03
Also published as: US20160051181A1; WO2014154877A1; US10448880B2; FR3003746B1; FR3003746A1

Abstract

The present invention relates to a method which makes it possible to measure flushing, particularly in the context of the study of rosacea, and to distinguish normal flushing from pathological flushing. The invention also relates to the use of said method to study the effect of drug candidates, particularly against rosacea. The method includes: a) subjecting the subject to a flushing-inducing stimulus; b) measuring the inflow of blood in the face of the subject during a time period covering the flushing; and c) calculating entropy of the inflow of blood.

Description

Flush measurement method and use for evaluation of treatments Field of the invention

The present invention relates to the field of medicine. In particular, it relates to a method for measuring flush.

Context of the invention

Rosacea is a chronic and progressive joint inflammatory dermatosis related to vascular disorders. It mainly affects the central part of the face and is characterized by redness of the face accompanied by hot flushes, facial erythema, papules, pustules, telangiectasias and sometimes ocular lesions called ocular rosacea. In extreme cases, particularly in humans, there is hypertrophy at the nasal level called rhinophyma. Rosacea evolves over several years by outbreaks aggravated by different stimuli such as temperature changes, alcohol, spices, sun exposure or emotions.

Rosacea is classified into 4 subtypes according to various clinical features (Wilkin J et al, JAAD, 2002, 46: 584-587).

Subtype 1: also called erythematotelangiectatic rosacea, is characterized mainly by flushing and persistent central facial erythema. The presence of telangiectasia is common, but not essential to the diagnosis of this subtype. Central facial edema, burning and stinging, and roughness or desquamation are also sometimes observed. The patients have erythrose attacks due to the sudden dilation of the arterioles of the face which then takes on a congestive, red appearance. These outbreaks are caused by emotions, meals, temperature changes and are referred to as flush.

Subtype 2: also called papulopustular rosacea, which is characterized by an inflammatory stage with appearance of inflammatory papules and pustules but without involvement of the sebaceous follicle and therefore with an absence of cysts and comedones. Papulopustular rosacea is characterized by persistent central facial erythema and transient papules and / or pustules distributed in the center of the face. However, papules and pustules may also affect the peri-oral regions (i.e. the perioral, perineal or periocular areas). The papulopustular subtype is reminiscent of acne vulgaris, but comedones are absent. Rosacea and acne can coexist and, in addition to papules and pustules suggestive of rosacea, the patients concerned may also present comedones. Patients with papulopustular rosacea may complain of burning and stinging. Subtype 3: Phosphate Rosacea (Rhinophyma)

Phosphate rosacea is manifested by thickening of the skin, nodules with an irregular surface and swelling. Rhinophyma is the most common presentation, but phymatous rosacea may affect other territories, including the chin, forehead, cheeks and ears. In patients with this subtype, the presence of enlarged and prominent follicular apertures is sometimes reported in the affected area, as well as telangiectases. This late phase mainly affects men. Patients have a bulging, red, bumpy nose with sebaceous hyperplasia and fibrous remodeling of the connective tissue.

Subtype 4: called ocular rosacea (or ophthalmic rosacea). Ocular rosacea is often misdiagnosed or underestimated as a cause of conjunctival inflammation. The diagnosis of ocular rosacea should be considered when a patient has one or more of the following eye signs and symptoms: tearful or bloody (conjunctival hyperemia), foreign body sensation, burning or stinging, dryness, itching, photosensitivity , blurred vision, telangiectasias of the conjunctiva and eyelid margin or erythema of the eyelid and periocular. Blepharitis, conjunctivitis and irregular margins of the eyelid are other signs that may be detected. A chalazion or chronic staphylococcal infection manifested by a stye, and the cause of which is a dysfunction of the Meibomian glands, is a common sign of rosacea-related eye disease. Some patients will complain of a decrease in visual acuity, which is due to corneal complications (punctate keratitis, corneal infiltrates / corneal ulcerations or marginal keratitis).

A history of flushing is common in patients with erythematotelangiectatic rosacea (subtype 1) and sometimes also in patients with papulopustular rosacea (subtype 2).

The flush is a congestive or vasomotor burst, a phenomenon that results in the appearance of transient redness mainly in the face and accompanied by a sensation of heat. This symptom is common to several pathologies including rosacea.

The flush can be triggered by different stimuli of everyday life: rapid change of temperature, diet, alcoholic beverages.

His unexpected and fleeting nature makes his study difficult. Currently in clinical trials, the evaluation of the effectiveness of drug candidates is carried out through questionnaire given to the patient who records in his daily life the appearance of this symptom and tries to characterize it.

Some methods have been proposed to measure the flush. For example, Wilkin (J Invest Dermatol, 1981, 76, 15-18) proposed to use a thermal circulation index. This index is the ratio of the effective thermal conductivity of skin tissues to the effective thermal conductivity of the environment. To measure the flush, this author proposes to measure the temperature of the malar skin and to measure the malar thermal circulation index. These parameters are measured before the stimulus and at the time of the maximum malar temperature change. Then he studies the relationship between these two measures. Moreover, the time between the application of the stimulus and the moment corresponding to the half maximum change of malar temperature was measured. However, these methods do not make it possible to differentiate a pathological flush (in particular from a subject suffering from rosacea) from a normal flush (healthy subject).

Thus, there is still a strong need for a more rigorous and reproducible method for measuring flushing, particularly those related to rosacea, and thus to evaluate the impact of drug candidates on this symptom. In particular, there is a need for a method that is not based solely or solely on the patient's judgment and makes it possible to obtain statistically significant results with the smallest possible group of patients.

Summary of the invention

The inventors have developed a method for measuring flushes in a significant and reproducible manner in a small number of subjects and making it possible to discriminate between flushes related to rosacea and those of subjects not suffering from this disease. The results obtained by this method are perfectly correlated with those obtained by conventional clinical evaluation. This method can therefore be used in tests to evaluate the efficacy of rosacea drug candidates, particularly in clinical trials. In addition, the method has the advantage of not depending on self-evaluation of the patient.

The present invention therefore relates to a method for measuring a flush in a subject comprising:

a) subjecting the subject to a stimulus inducing a flush;

b) measuring the influx of blood to the subject's face for a period of time covering the flush; and, c) calculating the entropy of the blood flow.

Preferably, the measurement of the blood flow to the face is made by measuring the intensity of the blood flow in the superficial cutaneous portions of the face and / or the measurement of the color of the skin of the face, in particular redness.

Preferably, the measurement of the intensity of the blood flow in the superficial cutaneous portions of the face is carried out by measuring the blood circulation, for example by a system based on the Doppler effect or by a system based on the analysis. contrast of laser granularity. In particular, the measurement of the intensity of the blood flow in the superficial cutaneous portions of the face is carried out by analysis of the laser granularity contrast, in particular using a FLPI (Full Field Laser Perfusion Imaging) imager.

In particular, the measurement of the blood flow, preferably the intensity of the blood flow in the superficial cutaneous portions of the face, is performed on one or both cheeks. Preferably, the period of time during which the blood flow is measured, preferably the blood flow intensity, is between 30 minutes and 1 hour 30 minutes, preferably between 45 minutes and 60 minutes.

Optionally, the method further includes regularly evaluating the feeling of warmth felt by the subject.

The flush-inducing stimulus may be selected from a hot beverage, the absorption of a spice or an alcoholic beverage, preferably a hot beverage or the absorption of a spice, more preferably a hot beverage.

Preferably, the computed entropy is indicative of either a normal flush or a pathological flush, particularly characteristic of rosacea. The computed entropy can be compared to a range of reference entropy values, preferably to a range of entropy values characteristic of a normal flush and / or to a range of entropy values characteristic of a flush. pathological, in particular characteristic of rosacea.

Preferably, the entropy is calculated by the following formula:

Entropy = -Σ (N (i) / Nt * log (N (i) / Nt))

with N (i) is the number of points per intensity interval of the blood flow;

Nt is the total number of points, Nt = Σ N (i).

In a particular embodiment, several flush measurements are made for a subject. In particular, measurements can be made on the left and right cheeks of the subject and the entropy is calculated either for each cheek or by averaging the two cheeks.

In a particular embodiment, the measurement is performed on a subject before and after treatment with a drug or drug candidate, a cosmetic product or a medical device, in particular for the treatment of rosacea. In a first embodiment, the measurement is performed on a subject on one cheek that has not received treatment or received a reference treatment or a placebo, and on the other cheek that has been treated with a drug. or a drug candidate, a cosmetic product or a medical device. In another embodiment, the measurement is performed on a subject before and after treatment with a drug or drug candidate, a cosmetic product or a medical device. Preferably, the entropy calculated without treatment or with treatment by a reference treatment or a placebo and with treatment with a drug or drug candidate, a cosmetic product or a medical device, are compared and make it possible to determine the therapeutic efficacy of said drug or drug candidate, cosmetic product or medical device. Preferably, the drug or drug candidate, cosmetic product or medical device is for the treatment of rosacea. In a preferred embodiment, the subject is a subject suffering from rosacea.

Thus, the present invention relates to the use of the method of measuring a flush in a subject to determine the effectiveness of a drug or drug candidate, a cosmetic product or a medical device, including having to reduce or eliminate pathological flushes, particularly those associated with rosacea. In particular, pathological flushes are associated with rosacea of subtype I, erythemotelangiectatic or subtype II, papulopustular.

Detailed description of the invention

The present invention relates to a method for measuring flushes. This method has the advantage of being able to differentiate pathological flushes, especially those associated with rosacea, normal flushes, that is to say, subjects with no pathology. This method gives a reproducible result and makes it possible to carry out statistically significant studies with a small number of subjects, in particular about ten subjects. Thus, the present method is extremely useful for testing the effectiveness of a treatment intended to reduce or eliminate pathological flushes, especially those associated with rosacea.

a) subjecting the subject to a stimulus inducing a flush;

The stimulus used may be selected from those well known to those skilled in the art. For example, it may be a hot drink, for example 40-70 ° C, especially at 60 ° C, the absorption of a spice, including tabasco or chilli, or an alcohol as a wine. The hot drink can be water, coffee or tea. In a preferred embodiment, the stimulus is a hot beverage or the absorption of a spice. In the preferred embodiment, the stimulus is a hot drink.

Optionally, before administering the stimulus, the subject will have been installed and left for a relaxation time, for example about 30 minutes.

Following the application of the stimulus, the blood flow to the subject's face is measured. The blood flow is measured during a period covering the flush. For example, it is measured from the moment of the stimulus until the end of the flush. This period preferably lasts from 30 minutes to 1 hour 30 minutes. In a preferred embodiment, it lasts 45 to 60 minutes. In one preferred embodiment, it lasts approximately 45 minutes. The measurement period may also include a period before the application of the stimulus. This sets a base level.

The blood flow is measured throughout the chosen period. Preferably, it is measured every minute, preferably every 10 to 50 seconds, more preferably at a frequency of at least every 10 seconds, for example at least or approximately every 5 seconds, 2 seconds or 1 second.

The blood flow can be measured in different ways.

For example, the inflow of blood to the face can be measured by measuring the intensity of blood flow in the superficial cutaneous parts of the face, by measuring the color of the skin of the face, especially the redness, by a regular evaluation of the sensation of heat felt by the subject, or by a combination of two or three of these parameters.

Thus, in a first embodiment, the blood flow to the face is measured by measuring the intensity of blood flow in the superficial cutaneous portions of the face. In addition, this measurement can be combined with the measurement of the color of the facial skin, in particular redness, and / or a regular evaluation of the sensation of heat felt by the subject. Preferably, this measurement can be combined with the measurement of the color of the skin of the face, in particular the redness.

In a second embodiment, the blood flow to the face is measured by measuring the color of the skin of the face, in particular the redness. In addition, this measurement can be combined with the measurement of the intensity of blood flow in the superficial cutaneous parts of the face and / or a regular evaluation of the sensation of heat felt by the subject. Preferably, this measurement can be combined with measuring the measurement of the intensity of blood flow in the superficial cutaneous parts of the face.

The blood flow can be measured in the superficial cutaneous parts of the face corresponding to the forehead, chin and / or cheeks. In a preferred embodiment, it is measured at the cheeks. In a preferred embodiment, the blood flow is measured for each of the cheeks.

When the method includes the measurement of the intensity of blood flow in the superficial cutaneous parts of the face, this measurement is carried out by a measurement of the blood microcirculation, for example by a system based on the Doppler effect or by a system based on contrast analysis of laser granularity. In particular, the measurement of the intensity of the blood flow in the superficial cutaneous portions of the face is carried out by analysis of the laser granularity contrast, in particular using a FLPI (Full Field Laser Perfusion Imaging) imager. In a preferred embodiment, cutaneous microcirculation is measured with a FLPI (Full Field Laser Perfusion Imaging) imager. For example, the apparatus marketed by Moor can be used.

When the method comprises the measurement of the color of the skin of the face, in particular the redness, the measurement of the redness can be carried out by any system making it possible to measure the color, preferably without contact, for example spectrodradiameter, spectral / multispectral imaging , digital camera, or camera.

When the method includes a regular evaluation of the sensation of heat felt by the subject, this evaluation will be made by the subject every 5 to 10 minutes. In particular, this can be done by determining a scale of scores. For example, such a scale can be: 1 for no sensation of heat; 2 for very slight sensation of heat; 3 for slight feeling of heat; 4 for moderate heat sensation; 5 for strong feeling of heat.

Based on the measurement of blood flow as a function of time, it is then possible to calculate the entropy of the intensity of the blood flow.

Indeed, the inventors have noted that, surprisingly, healthy subjects also presented a flush following the application of stimulus. It was therefore important to distinguish a flush associated with a pathology such as rosacea, especially a subtype I rosacea, from a flush of a healthy subject. The inventors have found that it is difficult to define an analysis factor that makes it possible to discriminate between the two groups. Indeed, the maximum intensity was not discriminating. Although the duration of the flushes of subjects with rosacea seems longer, this criterion was not sufficient to discriminate between the two groups, especially when the number of subjects studied is small. The area under the curve of the blood flow intensity versus time curve may possibly be used, but this criterion requires large numbers of subjects to be able to be used.

It is thus quite surprising that the inventors have identified entropy as a criterion capable of discriminating between the two groups in a reproducible manner and on very small subject sizes. Indeed, a dozen subjects is sufficient.

To calculate this entropy, the skilled person can use any well known methods to evaluate or calculate the entropy of a signal.

In particular, any method for estimating whether the subject spends more time in high blood flow values.

In a preferred embodiment, the entropy of blood flow intensity can be calculated by Shannon entropy. Thus, this entropy can be calculated by the following formula:

Entropy = -Σ (N (i) / Nt * log (N (i) / Nt))

with N (i) is the number of points per intensity interval of the blood flow;

Nt is the total number of points, Nt = Σ N (i).

The intensity interval of the blood flow is defined by those skilled in the art according to the precision he wishes to have.

For example, considering the range covered by the minimum and maximum blood flow intensities, one can choose to subdivide this range into a number of intervals. In particular, the number of intervals can be between 20 and 500, preferably between 50 and 250.

Alternatively, it may be chosen to define the intervals by a blood flow intensity interval. For example, the ranges may be from 20 to 250, preferably from 10 to 50.

Thus, entropy is obtained. The computed entropy can then be compared to reference values. The reference entropy values may be those characteristic of pathological flushes, in particular associated with rosacea, and / or those characteristic of normal fushs. On the basis of this comparison, it can be determined whether the entropy corresponds to a normal patient, that is, to a healthy subject, or to a pathological disease, particularly characteristic of a subject suffering from rosacea. In another preferred embodiment, the blood flow intensity data as a function of time can be transformed into a diagram according to the principle explained in FIG. 5. Thus, blood flow intensity intervals are defined. For example, they can be defined as detailed above. Then, the number of points per intensity interval of the blood flow is determined. It corresponds to the Ni defined above. Finally, the diagram representing the number of points as a function of the intensity intervals is prepared. On the basis of this diagram, it is possible to distinguish pathological flushes, particularly associated with rosacea, from those that are normal (Figures 6 and 7). Indeed, in this form of representation, the inventors have observed that normal flushes are characterized by a narrow peak while pathological flushes are characterized by a spread of average intensity curve.

In one embodiment, a plurality of flush measurements are performed for a subject according to the present method. For example, for the same subject, one can make measurements on the left and right cheeks of the subject and one computes the entropy for each cheek, or by averaging the two cheeks.

The present invention relates to the use of the method for measuring a flush in a subject according to the present invention to determine the effectiveness of a drug or drug candidate, a cosmetic product or a medical device, in particular having for to reduce or eliminate pathological flushes, particularly those associated with rosacea, preferably subtype I rosacea, or subtype II rosacea, or to provide information useful for determining the efficacy of a drug or drug candidate, a cosmetic product or a medical device ,.

Thus, the present invention relates to a method for determining the effectiveness of a drug or drug candidate, a cosmetic product or a medical device, having in particular the purpose of reducing or eliminating pathological flushes, or generating information useful for determining the efficacy of a drug or drug candidate, a cosmetic product or a medical device, in which several flush measurements are made. By "flush measurement" is meant the steps of stimulus application and measurement of blood flow. Indeed, the entropy can be calculated directly following these two steps or later during the analysis of the results.

In particular, several flush measurements are made in the same subject at several times. Preferably, a measurement is made before the initiation of the treatment with the drug or drug candidate, the cosmetic product or the medical device. Then, a measurement is made at the end of the treatment with the drug or drug candidate, the cosmetic product or medical device. Finally, several intermediate measures can be performed during the treatment with the drug or drug candidate, the cosmetic product or the medical device. The entropies can be calculated on the totality of the acquired signal or on a part of the signal, in particular on the signal acquired before the stimulus and on the signal acquired after the stimulus. Entropies calculated after or during treatment are compared with calculated entropy before treatment initiation. If the entropy calculated after or during the treatment is less than the entropy calculated before the initiation of treatment, the drug or drug candidate, cosmetic product or medical device, may be considered effective, including effective to reduce or eliminate the pathological flushes. In particular, it is also possible to compare the entropy calculated after or during the treatment with reference entropy values and to determine whether the computed entropy corresponds to a normal flush, that is to say in a healthy subject, or to a pathological flush, especially characteristic of subject suffering from rosacea. Preferably, this method is applied to a group of subjects, for example a group comprising at least 10, 15 or 20 subjects, in particular a group of 10 to 100 subjects.

This method may also include control groups. The control groups may be subjects suffering from the pathology and who are treated with a reference medicine, such as a drug known for its effectiveness, particularly effective in reducing or eliminating pathological flushes. The control groups may also be subjects suffering from the pathology and who are treated with a placebo or who have not received treatment.

Alternatively, it may be envisaged to use the subject as a control. Thus, for example, the subject was treated for one half of the face with the drug or drug candidate, the cosmetic product or the medical device, while the other half of the face was treated with a reference drug, a placebo or did not receive treatment. In particular, the parts of the face concerned are the cheeks. In this context, a measure of flushes is made on each cheek and the entropy is calculated for each of the cheeks. As in the previous embodiment, flush measurement is preferably performed prior to initiation of treatment with the drug or drug candidate, the cosmetic product or the medical device, and also at the end of treatment, and optionally during the course of treatment. treatment. Thus, in addition to the data corresponding to the evolution of the entropy as a function of the treatment, it is also possible to compare on the same subject the entropy calculated for one cheek with that calculated for the other cheek. Preferably, the drug or candidate drug is intended for the treatment of rosacea, subtype I, or rosacea erythemotelangiectasis and subtype II or papulopustular and more particularly rosacea of subtype I, erythemotelangiectatic. In a preferred embodiment, the subject is a subject suffering from rosacea, in particular rosacea of subtype I, erythemotelangiectatic.

The following examples will now be given by way of illustration and without any limitation.

Description of figures

Figure 1: Schematic description of the flush phenomenon representing a curve of recorded signal intensity as a function of time when measuring blood flow in the superficial cutaneous parts of a cheek.

Figure 2: Histogram representing the maximum factor of intensity change from basal level in healthy subjects and subjects with rosacea.

Figure 3: Histogram showing the duration of flush in healthy subjects and in subjects with rosacea.

Figure 4: Histogram showing area under the curve (AUC) in healthy subjects and subjects with rosacea.

Figure 5: Explanatory diagram of the method for preparing the histogram representing the number of points as a function of the signal intensity intervals from a curve of the recorded signal strength as a function of time during the measurement of the signal strength. circulatory flow.

Figure 6: Averaged histogram representing the number of points as a function of intensity intervals (100 intervals) of the signal for a cheek (number of subjects = 12 subjects with rosacea (dotted line) and 13 healthy subjects (solid line).

Figure 7: Normalized histogram for healthy subjects (Fig 7 A) and for subjects with rosacea (Fig 7B) using signals after the stimulus.

Figure 8: Histogram representing the average entropy as measured on the cheeks for 3 consecutive days for 10 subjects (250 intervals) (left, right cheek (2), right, cheek left (3)).

Figure 9: Histogram representing the average entropy as measured on the cheeks after the hot water stimulus for 12 subjects with rosacea and 13 healthy subjects (250 intervals) (left, right cheek (2), right cheek left (3)). Figure 10: Histogram representing mean entropy as measured on the cheeks after the tabasco stimulus for 12 subjects with rosacea and 13 healthy subjects (250 intervals) (left, right cheek (2), right, left cheek ( 3)).

Figure 11: Histogram showing the sum of the entropies as measured on both cheeks after the hot water (A) or tabasco (B) stimulus for 12 subjects with rosacea and 13 healthy subjects (250 intervals) (left, play right, right plays left).

Figure 12: Table showing, according to the stimulus used and the parameter measured, the number of subjects necessary to differentiate the flush of the healthy subjects and the flush of the subjects suffering from rosacea.

Examples

Methodology

Patients:

15 patients with rosacea subtype I

15 healthy subjects.

The stimulus, administered orally, was:

Water at 60 ° C, 200 ml; or

Tabasco (6 drops)

Procedure:

Installation of the subject and rest for 30 minutes.

Measures after stimulus for 45 minutes including:

Measurement of blood flow in the superficial cutaneous areas (FLPI = Full Field Laser Perfusion Imaging) of the face. For the face, the measurement was made at the level of each cheek. The cutaneous microcirculation was measured with a FLPI imager from the company Moor using laser granularity contrast analysis (LASCA).

The intensity of the blood flow as a function of time is obtained (see the curve of Figure 1 for illustration).

Results analysis:

Several parameters were taken into account for the analysis of the results. Indeed, on the basis of the curves obtained (see Figure 1 for illustration), the following parameters were measured:

The maximum intensity during the flush; The duration of the flush; and

Area under the curve (AUC).

Analysis of results by entropy:

Based on the intensity of the blood flow as a function of time, this curve was treated in the following manner (for illustration, see Figure 5). The number of points per blood flow intensity interval was determined, and then a histogram is plotted representing the number of points N (i) as a function of the intensity intervals. The intensity interval that was used for the generation of results is 20.

More precisely, the entropy of the signal calculated using the histogram can be calculated by the following formula (Shannon entropy):

Entropy = -Σ (N (i) / Nt * log (N (i) / Nt))

with N (i) the number of points per intensity interval

Nt the total number of points, Nt = Σ N (i).

The histograms of the signal can be prepared separately by subject (example of histogram Figure 5). Alternatively, to minimize interindividual variability, histograms can also be prepared using data obtained for several subjects in the same category, either healthy or with rosacea.

In the same way, the entropies can be calculated for each subject by the formula indicated above. Then, calculated entropies can be used to calculate entropy averages for several subjects in the same category, either healthy or with rosacea.

The entropies can be calculated on the totality of the acquired signal or on a part of the signal, in particular on the signal acquired before the stimulus and on the signal acquired after the stimulus.

Results

The first parameters that were taken into account for the analysis of the results were the maximum intensity during the flush, its duration and the area under the curve.

Based on these parameters and with the number of subjects considered, it was determined by the inventors that it was not possible to distinguish statistically significant flushes of healthy subjects from those of subjects suffering from rosacea: see Figure 2 for the maximum intensity; Figure 3 for the duration of the flush; and Figure 4 for the area under the curve. The inventors have therefore sought another method of analyzing blood flow data to be able to distinguish the response of healthy subjects from that of subjects suffering from rosacea. For this, they built the histograms of the signal (see Figure 5) that allowed the calculation of the entropy of the signal.

Histograms of the signals yielded curves that clearly differ between healthy subjects and subjects with rosacea (Figures 6 and 7). Indeed, in healthy subjects, a very large number of points are present for the intervals of low signal intensities, whereas, in subjects suffering from rosacea, a moderately high number of points presenting a great variability of signal intensity. is observed.

On the basis of these data, an entropy was calculated as indicated above

(entropy of Shannon). As shown in Figures 9-11, statistically different entropies were obtained for both groups of subjects.

The measurement of the flushes was made three consecutive days on 10 subjects. As shown in Figure 8, this measurement is reproducible over three consecutive days.

Figures 9-11 show that computed entropy allows statistically significant flushes of healthy subjects to be distinguished from subjects with rosacea.

In the experimental and analytical conditions used with FLPI, considering an intensity interval of 20 for the calculation of histograms, we observe that healthy subjects have an entropy value around 4.5, whereas subjects suffering from rosacea have an entropy value around 5.2.

Finally the table of Figure 12 shows that the flush measurement method developed by the inventors is very advantageous since a cohort of about ten subjects is sufficient. On the other hand, if the criterion of the area under the curve was used, it should not be less than 55 subjects at least.

Claims

claims

1- Method for measuring a flush in a subject comprising:

a) subjecting the subject to a stimulus inducing a flush;

b) measuring the influx of blood to the subject's face for a period of time covering the flush; and,

c) calculating the entropy of the blood flow.

2- Method according to claim 1, wherein the measurement of the blood flow to the face is achieved by measuring the intensity of blood flow in the superficial cutaneous portions of the face and / or the measurement of the color of the face. facial skin, especially redness.

3. Method according to claim 2, in which the measurement of the intensity of the blood flow in the superficial cutaneous portions of the face is carried out by a measurement of the blood microcirculation, for example by a system based on the Doppler effect or by a system based on laser granularity contrast analysis. 4. Method according to claim 3, in which the measurement of the intensity of the blood flow in the superficial cutaneous portions of the face is carried out by analysis of the laser granularity contrast, in particular using a FLPI (Full Field Laser) imager. Infusion Imaging). 5. Method according to any one of the preceding claims, wherein the measurement of the inflow of blood is performed on one or both cheeks.

6. Method according to any one of the preceding claims, wherein the period of time during which the inflow of blood is measured is between 30 min and 1 h 30, preferably between 45 min and 60 min.

7- Method according to any one of the preceding claims, wherein the method further comprises the regular evaluation of the sensation of heat felt by the subject. The method according to any one of the preceding claims, wherein the flush-inducing stimulus is selected from a hot beverage, the absorption of a spice or an alcoholic beverage, preferably a hot beverage or the absorption of a spice, preferably still a hot drink.

9- Method according to any one of the preceding claims, wherein the computed entropy is indicative of either a normal flush or a pathological flush.

A method as claimed in any one of the preceding claims, wherein the computed entropy is compared to a range of reference entropy values, preferably to a range of entropy values characteristic of a normal flush and / or to a range of entropy values characteristic of a pathological flush.

11- Method according to any one of the preceding claims, in which the entropy is calculated by the following formula:

Entropy = -Σ (N (i) / Nt * log (N (i) / Nt))

with N (i) is the number of points per intensity interval of the blood flow;

Nt is the total number of points, Nt = Σ N (i).

12- Method according to any one of the preceding claims, wherein several flush measurements are made for a subject.

13- Method according to claim 12, in which measurements are made on the left and right cheeks of the subject and the entropy is calculated either for each cheek or by averaging the two cheeks.

14- Method according to claim 12 or 13, wherein the measurement is performed on a subject before and after treatment with a drug or drug candidate, a cosmetic product or a medical device.

15. The method of claim 12 or 13, wherein the measurement is performed on a subject on a cheek that has not received treatment or has received treatment. reference or a placebo, and on the other cheek that has received treatment with a drug or drug candidate, a cosmetic product or a medical device.

16- Method according to claim 14 or 15, wherein the entropy calculated without treatment or with treatment with a reference treatment or a placebo and with treatment with a drug or drug candidate, a cosmetic product or a medical device, are compared and allow to determine the therapeutic efficacy of said drug or drug candidate, cosmetic product or medical device.

17- Method according to one of claims 14 to 16, characterized in that the drug or the drug candidate is for the treatment of rosacea.

18- Use of the method according to any one of claims 1-17 to determine the effectiveness of a drug or drug candidate, a cosmetic product or a medical device, in particular to reduce or eliminate the pathological flushes.

19. Use of the method according to claim 18, wherein the pathological flushes are associated with rosacea.

20. Use of the method according to claim 19, wherein the pathological flushes are associated with rosacea subtype I, erythemotelangiectatic.

21. Use of the method according to claim 19, wherein the pathological flushes are associated with rosacea of subtype II, papulopustular.