Complete skin clearance and Psoriasis Area and Severity Index response rates in clinical practice: predictors, health-related quality of life improvements and implications for treatment goals.

PASI percentage change is largely dependent on absolute PASI before switch. Patients in clinical practice lack 'baseline' PASI values as they may switch directly from one treatment to another or stay successfully treated for a longer time period. Treatment goals such as PASI 90 are thus not suitable for treatment guidelines or for follow-up in clinical practice. What's already known about this topic? Randomized clinical trials of biologics as well as treatment guidelines include treatment goals based on a percentage improvement compared with baseline Psoriasis Area and Severity Index (PASI), such as PASI 75 or PASI 90. Few studies have assessed which factors are associated with high skin clearance rates, or health-related quality of life (HRQoL) improvements associated with different levels of skin clearance in clinical practice. What does this study add? A high absolute PASI before switch to biologics and low body mass index are associated with higher PASI percentage response. Few patients with baseline PASI >30 achieved complete skin clearance (CSC). All responder groups achieved significant HRQoL improvements. Patients achieving CSC (PASI 100) had lower absolute PASI before switch and lower improvements in absolute PASI and HRQoL than patients with almost cleared skin. What are the clinical implications of this work? Relative measures based on PASI percentage, such as PASI 75 or PASI 90, are not suitable for treatment guidelines or for follow-up in clinical practice.