THE CLINICAL EVALUATION OF ANTIDANDRUFF SHAMPOOS 443 SPECIAL PROBLEMS OF DANDRUFF TRIALS One of the main considerations is the decision on what is to constitute a favourable result for an individual participant. It may, for example, be shown that any shampoo, whether medicated or not, will remove some 70% of ('•andruff scale during the actual process of shampooing. In the absence of effective treatment, however, dandruff will return to approximately the original level within about five days what matters to the subject is that this recurrence should not happen, at least to the same extent. Hence an antidandruff shampoo can only be classed as effective if it significantly and consistently reduces the dandruff levels attained five days after shampooing and it is appropriate always to take measurements at this timing as far as possible. It should not be forgotten that clinical trial techniques stand or fall by the extent of cooperation achieved with the participants, and there is an ever-present hazard that some of the subjects may not really have used the test or control products at all, especially if they are unpleasant or complicated in use or deemed to be ineffective. Similarly precise timing of observations after shampooing is a target to be aimed at and it has to be hoped that minor discrepancies will cancel out between the panels. Recruitment of subjects for dandruff studies presents surprising difficulty. Obviously someone who has no dandruff cannot show any beneficial effect, however efficacious the treatment. It is therefore necessary to recruit at least moderately severe sufferers, though it is also desirable to have some subjects who are only slightly affected in case either the test or control product demonstrates an adverse effect. It is quite impossible to ensure that a sample of subjects in a thai is fully representative of the population as a whole, if panels are to be kept within manageable propor- tions for instance, the source of infection in one geographical area may differ from others and may also differ in response to particular treatments (assuming that dandruff results from infection). If the subjects for a trial are recruited from an essentially "closed" community such as a boarding school, the risk of bias due to atypical sampling may be serious. On the other hand, it may be much easier to obtain the desired level of cooperation in such a community and far simpler to make suitable arrangements for conducting inspections. Probably the most satisfactory answer in practice is to utilize several such "closed" communities for the full evaluation of a new product. Subjects who are skin patients attending hospital are not ideal for the purpose, as they may not respond in the same way as "normals". Some published clinical trials on dandruff appear to have been restricted

444 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS to recording the overall impressions of a dermatologist, the findings being expressed in a limited range of descriptive terms such as "cleared", "im- proved" or "no change"(3). Brief consideration will show that such an approach (especially if it is not accompanied by a strictly "double-blind" routine) leaves much to be desired unless it is only required to distinguish all-or-none efficacy. Important factors, in our experience, are that:-- i. Training and extensive practice in the study of dandruff, making use of the concordance tests previously described {1), are pre-requisites for discriminating and reproducible assessments. ii. Clear definitions for a gradation of clinical features are necessary, along with a definite system for examining the scalp. Observations may take the form of word descriptions at the time of examination but are preferably transcribed into pre-selected numerical values for subsequent tabulation and analysis. iii. Intervals between inspections, during which the various treatments are used, need to be programmed on sound lines. The technique of examining the scalp in 25 sections (1) has formed the basis of much of our experience for several years. If this is used in conjunc- tion with a "double-blind" system of test and control panels, it is possible to compare the average trends for each panel during treatment. Since each physical examination occupies almost 30 min/subject, relatively small panels have to be employed and it becomes arguable whether a less detailed inspection of larger numbers would not be more profitable. Clearly the point could be reached where the technique of assessment became so crude that only the most glaring differences could possibly attain statistical significance we have therefore sought to test some comparatively simple techniques and are still continuing such investigations. Our own staff of observers, who have long experience in the detailed, 30 min method of assessing dandruff, have more recently been trained to conduct a quicker method of inspection which takes about five min. In the detailed method the scalp is partitioned into 25 imaginary sections and each section in turn is scored for severity of dandruff and proportion of area occupied by dandruff in the rapid method the scalp is divided into four sections instead of 25. The subject is seated under a good diffused lighting and each notional quadrant is examined by parting the hair with a comb at intervals over the area. The estimated amount of scale attached to the scalp {not loose in the hair) for each quadrant is rated by the following verbal descriptions, which are later given the numerical values shown and added together to yield the index for the whole scalp.