BackgroundThis post-hoc analysis of PsABio (NCT02627768) evaluated safety, effectiveness and treatment persistence in patients < 60 and ≥ 60 years of age receiving ustekinumab over 3 years.MethodsMeasures included adverse events (AE), clinical Disease Activity Index for Psoriatic Arthritis (cDAPSA) low disease activity (LDA) including remission, Psoriatic Arthritis Impact of Disease-12 (PsAID-12), Minimal Disease Activity, dactylitis, nail/skin involvement and time to treatment stop. Data were analysed descriptively.ResultsOverall, 336 patients < 60 and 103 ≥ 60 years received ustekinumab, with a similar gender balance. A numerically lower proportion of younger patients reported at least one AE: 124/379 (32.7%) vs 47/115 (40.9%) for patients < 60 and ≥ 60 years, respectively. Serious AEs were low (< 10%) in both groups. At 6 months, the proportion of patients with cDAPSA LDA was 138/267 (51.7%) and 35/80 (43.8%) for patients < 60 and ≥ 60 years, respectively, with the effectiveness being maintained through 36 months. PsAID-12 mean scores reduced for both groups from a baseline mean of 5.73 and 5.61 for patients < 60 and ≥ 60 years, respectively, to 3.81 and 3.88, respectively, at 6 months, and 2.02 and 3.24, respectively, at 36 months. Regarding treatment persistence, 173/336 (51.5%) vs 47/103 (45.6%) patients < 60 and ≥ 60 years, respectively, stopped or switched treatment.ConclusionFewer AEs were observed over 3 years for younger versus older patients with PsA. There were no clinically meaningful treatment response differences. Persistence was numerically higher in the older age group.Supplementary InformationThe online version contains supplementary material available at 10.1186/s13075-023-03078-8.