Psoriasis Area Severity Index (PASI) and the Dermatology Life Quality Index (DLQI): the correlation between disease severity and psychological burden in patients treated with biological therapies

BackgroundMultiple metrics evaluate the efficacy of psoriasis treatment, but interestingly, the correlation between the mostly widely used clinical trial efficacy end point, the physician-rendered Psoriasis Area Severity Index PASI score and, the most widely used quality of life metric, the Dermatology Life Quality Index DLQI, is not always high. ObjectiveTo perform a systematic review to determine PASI to DLQI correlation. MethodsRCTs of biological agents for the treatment of moderate-to-severe psoriasis were reviewed in accordance with PRISMA guidelines. The mean percentage PASI improvement and change in mean DLQI values were recorded and compared for treatment groups from baseline to 10-16weeks of therapy. ResultsA search of the literature yielded 155 sources, of which 13 RCTs met inclusion and exclusion criteria. Percentage of PASI improvement from baseline correlates with DLQI changes with an r(2) value of 0.80 from baseline through weeks 10-16. When grouped by mean percentage reduction in PASI, agents demonstrating >75% mean reduction in PASI demonstrated a mean DLQI improvement over agents that achieved <75%-50% mean reduction in PASI or <50% mean reduction in PASI [minimal clinically important difference (MCID) 3.2]. In addition, a reduction in mean PASI of at least 75%, predicted a mean movement from DLQI band 3 to DLQI band 1, in all nine treatment arms demonstrating such efficacy. ConclusionsMean PASI and DLQI correlate predictably in patients with chronic moderate-to-severe plaque psoriasis undergoing treatment with biological agents. A reduction in PASI of at least 75% can translate to significant quality-of-life improvement in patients treated with these therapies.