Factor analysis of the Beer Sheva Psoriasis Severity Score (BPSS).

BACKGROUND The Beer Sheva Psoriasis Severity Score is a novel instrument for the assessment of psoriasis severity, designed for use in routine clinical conditions. OBJECTIVE To identify the main factors of the BPSS. METHODS The sample used to study the BPSS comprised 70 patients with psoriasis vulgaris treated by climatotherapy at the Dead Sea. Psoriasis severity was assessed using BPSS and PASI (Psoriasis Area and Severity Index). Factor analysis was used to identify the main factors of BPSS. Internal consistency analysis was performed. Correlation matrices were generated to compare BPSS factors. RESULTS Factor analysis demonstrated that BPSS included six factors that explained 74.0% of the variance as follows: patient assessment 26.0%; physician assessment 13.2%; palms and soles involvement 11.9%; genitals, nails, and pruritus 9.0%; face involvement 7.3%; and scalp involvement 6.6%. Total scale Cronbach's alpha was 0.76; alpha for the factors ranged between 0.39 and 0.81. CONCLUSIONS The major factors of BPSS were identified. BPSS may be used as a comprehensive tool for measuring psoriasis severity.