Comparative analysis of disease outcomes: Early vs. late transition from psoriasis to psoriatic arthritis

Psoriasis typically precedes psoriatic arthritis (PsA). We explored whether the interval between the two diagnoses is associated with PsA phenotype and outcomes.

We constructed an inception (PsA duration ≤2 years) cohort of patients who developed PsA after psoriasis from a prospective observational cohort. All patients were diagnosed with PsA prior to or at their presentation to the clinic (baseline). We divided the cohort into early and late transition groups based on the median transition period between the diagnoses of psoriasis and PsA of nine years. Features associated with early and late transition at baseline were studied using logistic regression. The impact of early versus late transition on disease activity was assessed using multivariate linear regression, with the 5-year adjusted mean swollen joint count (SJC) as the outcome. The influence on damage was evaluated using Cox regression, with time to radiographic progression as the outcome.

We included 702 patients. Late transition patients were observed to have a younger age at diagnosis of psoriasis and older age at diagnosis of PsA. At baseline, they had higher BMI and PASI and less frequent use of conventional synthetic DMARDs. There was a trend for lower disease activity over time in the late transition group. Radiographic progression was not significantly different.

There were no significant differences in the PsA features at baseline between the two groups. However, on follow-up, there was a trend for lower cumulative disease activity but not in the rate of radiographic progression in the late transition group.