in patients with chronic moderate to severe plaque psoriasis (PASI ≥12; BSA ≥10%; static PGA ≥3) who were candidates for phototherapy and/or systemic therapy. Full details of the study design, inclusion and exclusion criteria, patient population, and primary safety and ef cacy results for ESTEEM 1 and ESTEEM 2 have been described previously.10,11
Analysis End Points and Assessments
Assessments in the present post hoc analysis included PASI, static PGA, BSA, and Dermatology Life Quality Index (DLQI) scores as determined according to the ESTEEM 1 and 2 clinical trial protocols at scheduled visits among patients receiving apremilast. The PASI score consisted of the sum of the erythema, induration, and desquamation for each body region, multiplied by weighted area scores, with higher scores (range: 0 to 72) indicating greater severity.3 The static PGA used in the ESTEEM 1 and 2 trials consisted of a 5-point rating scale ranging from 0 (clear) to 4 (severe) that re ects the severity of erythema, induration, and scaling across all psoriatic lesions (Table 2).10,11 Assessment of overall severity was made by factoring in areas that have already been cleared (ie, scores of 0) and remaining lesions for severity (ie, the severity of each sign is averaged across all areas of involvement, including cleared lesions). In the event of different severities across disease signs, the sign that is the predominant feature of the disease was used to help determine the static PGA score. Average erythema, induration, and scaling were scored separately over the whole body and the severity scores were summed and averaged including cleared lesions. The total average was rounded to the nearest whole number score to determine the PGA score and category. BSA was defined as the percentage of total body surface area involvement, with each 1% estimated based on the entire palmar surface of the patient’s hand. The PGAxBSA score was calculated by multiplying the static PGA score by the BSA (range: 0 to 400 [eg, maximum static PGA = 4 and maximum BSA = 100]).5 The DLQI, a 10-item patient-reported questionnaire commonly used to assess health-related quality of life in clinical trials of patients with chronic plaque psoriasis, was used to assess the impact of skin disease on quality of life and daily activities, with higher scores (range: 0 to 30) indicating worse quality of life.12
Statistical Analysis
Patients initially randomized to receive apremilast at baseline were included in the current post hoc analysis; at each time point, data as observed and suf cient for evaluation were used for analysis, with no imputation for missing values. Analyses were performed using SAS 9.2 (SAS Institute Inc., Cary, NC).
Correlation Between PGAxBSA and PASI
Spearman correlation coef cients were calculated to evaluate the relationship between PGAxBSA and PASI scores at baseline and at week 16 of apremilast treatment. Agreement between PGAxBSA and PASI scores was further assessed based on intra-class correlation coefficients and response concordance rates, using improvements from baseline of 50%, 75%, and 90% as the response thresholds in both scales. Specifically, at week 16, concordance was calculated as: (number of patients without PASI response and without PGAxBSA response) + (number of patients with PASI response and with PGAxBSA response) / the total number of patients with suf cient data for evaluation. Patients were considered overrated if response was achieved based on PGAxBSA, but not achieved based on PASI. Patients were considered underrated if response was achieved based on PASI, but not achieved based on PGAxBSA. PGAxBSA, and PASI responsiveness to therapeutic change was assessed based on effect sizes (vs placebo) at week 16. 
