The appearance and lifelong, chronic nature of psoriasis result in considerable burden to patients, such as sleep impairment, depressive symptoms, negative self-esteem and reduced work productivity. To examine direct and indirect (mediated) effects of secukinumab vs. ustekinumab on quality of life, work productivity and activity impairment based on psoriasis severity and symptoms. Analyses were based on data from the CLEAR study. Structural equation modelling examined the effects of secukinumab vs. ustekinumab on the Dermatology Life Quality Index (DLQI) and on the Work Productivity and Activity Impairment (WPAI) questionnaire using Psoriasis Area and Severity Index (PASI) severity and symptoms (pain, itching and scaling) as potential mediators. Analyses were conducted primarily for patients achieving a PASI 90 response (90% or greater reduction in PASI from baseline) at week 16 (repeated at week 52) and for PASI 50, 75 and 100. Results at weeks 16 and 52 showed that the effect of treatment on change in DLQI score was mediated by the PASI 90 response and by improvements in itching, pain, and scaling. Achieving any PASI response as early as week 16 directly resulted in significantly better WPAI scores. At week 52, both PASI response and improvement in scaling directly resulted in significantly better WPAI scores. Pain, itching and scaling were correlated (r = 0·51-0·68); improvement in any of these had a significant effect (directly or indirectly) on WPAI. All results favoured secukinumab over ustekinumab. The results underscore the important role of both PASI response and reduction in symptoms on improvements in health-related quality of life and work and daily activity in favour of secukinumab vs. ustekinumab. © 2018 British Association of Dermatologists.