Direct and Indirect Effect of Guselkumab on Anxiety, Depression, and Quality of Life in Patients with Moderate-to-Severe Plaque Psoriasis: A Mediation Analysis.

Introduction: Treating plaque psoriasis (PsO) with guselkumab (GUS) promotes skin clearance and is associated with improvements in health-related quality of life (HRQoL), anxiety, and depression. It is unclear whether improvements in patient-reported outcomes are due to resolution of skin symptoms or the direct result of GUS treatment.

Methods: Two phase 3, placebo- and active-comparator-controlled studies randomized patients with moderate-to-severe PsO to GUS, placebo (crossing over to GUS at week 16), or adalimumab. Post hoc mediation analyses examined direct and indirect effects of GUS, versus adalimumab, on Dermatology Life Quality Index (DLQI) or Hospital Anxiety and Depression Scale (HADS) after adjusting for indirect effects mediated by skin clearance, evaluated via Psoriasis Area and Severity Index (PASI), to determine the direct effect of GUS on dermatology HRQoL, depression, and anxiety.

Results: Compared with adalimumab, the natural direct effect (NDE) of GUS on change in DLQI from baseline was - 2.04 (P < 0.001), using PASI improvement as a mediator, indicating 89.2% of the total treatment effect was due to direct effects of GUS; using PASI 90 as a mediator, NDE of GUS was - 1.43 (P < 0.001), with 62.2% of the total treatment effect attributed to direct effects of GUS. Compared with adalimumab, 25.5% of change in HADS anxiety score was mediated through PASI improvement (NDE - 0.74; P = 0.002), indicating 74.5% of the total effect was independent of PASI improvement. Similarly, 24% of treatment effect was mediated through PASI 90 (NDE - 0.76; P = 0.002). Comparable proportions of the total improvement in HADS depression scores were due to direct and indirect effects of GUS mediated through PASI improvement (direct, 50.2%; indirect, 49.8%) or PASI 90 (direct, 59.5%; indirect, 40.5%).

Conclusions: GUS-mediated improvements in anxiety, depression, and overall HRQoL are not solely mediated by resolution of PsO signs, suggesting GUS use has a potential direct effect on anxiety and depression.