Study end‐points

The co‐primary end‐points were the proportion of patients achieving an IGA cleared/minimal (0/1) and PASI‐90 response (≥90% improvement in PASI from baseline) at week 16. The key secondary end‐points included the proportion of patients who achieved a PASI‐75 response (≥75% improvement in PASI from baseline) and change from baseline in the Dermatology Life Quality Index (DLQI) score at week 16.

Other secondary end‐points evaluated at week 16 and through week 52 include proportion of patients with IGA 0, IGA 0/1, PASI‐50, PASI‐75, PASI‐90 (≥90% improvement) and PASI‐100 (100% improvement); change and percentage improvement in the Nail Psoriasis Area and Severity Index (NAPSI) score from baseline; proportion of patients with a scalp‐specific Investigator's Global Assessment (ss‐IGA) score of 0 (absence of disease) or ss‐IGA 0/1 (very mild disease) who had a baseline score of 2 or more; proportion of patients who achieved a DLQI score of 0 or 1 (among patients with a baseline DLQI score of >1); and proportion of patients who achieved a reduction of 5 or more in the DLQI score from baseline. Changes from baseline in the EuroQOL 5 dimensions questionnaire (EQ‐5D) and physical and mental component summary (PCS and MCS) scores of the 36‐Item Short form Health Assessment Questionnaire (SF‐36) were assessed through week 48. In the subset of patients with active PsA, efficacy end‐points through week 52 included proportion of patients achieving American College of Rheumatology (ACR)‐20, ACR‐50 and ACR‐70 (≥20%, ≥50% and ≥70% improvement from baseline, respectively), improvements from baseline in the tender and swollen joint counts, improvements from baseline in the patient's assessment of pain (visual analog scale [VAS]) and patient's and physician's global assessment of disease activity, and proportion of responders on the Health Assessment Questionnaire – Disability Index.

Safety assessments included treatment‐emergent adverse events (TEAE) and laboratory evaluations through week 52. Antibodies to guselkumab in serum were detected using a validated, specific, sensitive and drug‐tolerant electrochemiluminescence immunoassay method using the Meso Scale Discovery platform (Gaithersburg, MD, USA) that incorporates an acid dissociation step to improve detection of antibodies to guselkumab in the presence of excess guselkumab.