THE CLINICAL EVALUATION OF ANTIDANDRUFF SHAMPOOS 447 the same subjects. Correspondence between the rapid (5 min) method and the original detailed 30 min method is illustrated in Fig. $. For levels in the moderate to moderately-severe region, there is little doubt that the two methods are in good agreement. There is a suggestion that the rapid method may be rather more sensitive at low and high levels of dandruff, possibly because the condition is often of patchy distribution and the scores tend to be "diluted" by the zero scores for clear areas in the detailed method. The distribution of points along the curve in Fig. $ reflects the efficacy of the treatment, but this is more readily examined in other ways, e.g. as -- 15o 1,1' 13, 12, 9' 8. 7' 3, 2. 1, 0 .--'• .... ,• ! USE Of PLACEBO /•t•tandard non-medicated , JSHAMPOO STARTS . I ,RE-TREATMENT P.ASE I TIME IN WEEKS TREATMENT PHASE Figure 4 Trial of an anti-dandruff shampoo containing 2% w/w zinc bis(pyridine-2-thiol 1-oxide). The points represent average levels for panels of 13 subjects, assessed by the detailed method. shown in Fig. •. The frequency of examinations helps to show the speed of response to the treatment as well as the maximum benefit obtained.
448 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Table II summarizes the data from a trial on the same shampoo, using the rapid inspection technique and the timing pattern discussed above, i.e. before treatment and after treatment for one and two months. The difference between the placebo effect and the treatment is clearly shown, though it should be remembered that expression as percentages does not necessarily accord precisely with the "true" gradations prevailing in vivo the analysis of variance undoubtedly yields a more reliable basis for judging the difference between test and control. Table II Trial of an anti-dandruff shampoo using the rapid method of assessment and a reduced number of observations Average level at 1 st examination for all subjects who reattended for 2rid examination Average level at 2nd examination reduction Average level at 1st examination for all subjects who reartended for 3rd examination Average level at 3rd examination reduction Placebo shampoo Test shampoo 9.3 (38 subjects) 21.8% 9.6 (37 subjects) 22.070 10.8 5.0 (39 subjects) •54.3% 11.0 (32 subjects) 70.9% Table IIA Analysis of variance of results in Table II Sum of Degrees of Mean Variance squares freedom variance ratio __ -- Between shampoos 105 1 105 5.8' Within shampoos 1370 75 18 Total 1475 76 Betwee n shampoo s 313 1 313 17'* * Within shampoos 1222 67 18 Total 1535 68 *Significant at 5 %, ***Significant at 0.1%, confidence level
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