Assessments
Two post hoc analyses were conducted on data pooled from the 2 phase 3 trials: (1) incidence of itching, and (2) total sign score (TSS) for lesions located on the knees and elbows.
Itching
Itching was assessed proactively by asking patients if they were experiencing itching (yes/no) at each visit (baseline and days 4, 8, 15, and 29) or had experienced itching since their last visit. As itching could be an adverse event of topical application, application-site pruritus was also recorded.
Total Sign Score
For each patient, a target plaque was selected that was representative of their psoriasis. The plaque was assessed on a 3-point grading scale for each of 3 key signs of plaque psoriasis: erythema, scaling, and plaque elevation (Table 1) at baseline and days 4, 8, 15, and 29. Total sign score was calculated by summing the scores for these 3 signs, resulting in a score ranging from 0 to 9. Treatment success was measured as (1) achieving a score of 0 or 1 (ie, reducing the plaque to clear or slight to mild) for the individual signs of erythema, scaling, and plaque elevation; and (2) achieving a TSS of 0 or 1 for all 3 signs—erythema, scaling, and plaque elevation—for each target lesion. Total sign score was assessed proactively for all patients.15,16 The post hoc analysis reported here examined patients whose target lesion was located on either the knee or the elbow.
Statistical Analyses
Because both study protocols were identical, data were pooled from the 2 phase 3 trials. All statistical analyses were performed using SAS software (SAS Institute). Two-sided hypothesis testing was conducted for all analyses using a significance level of P=.05. Post hoc analyses used Fisher exact test. No imputations were made for missing data.
Statistical analyses of itching compared the incidence of itching at each assessment time point (baseline and days 4, 8, 15, and 29) between BD spray and vehicle and between BD spray and AugBD lotion. Additional analysis included a statistical test on the incidence of itching in the subgroup of patients who reported itching at baseline.
Statistical analyses for the knees and elbows included only patients with their target lesion located on either the knee or the elbow. Analyses compared BD spray with vehicle and BD spray with AugBD lotion at days 4, 8, 15, and 29. Comparison with AugBD lotion treatment was up to day 14 only, consistent with application time limits in the AugBD lotion product label.18