Background/Purpose: Psoriatic arthritis (PsA) is a heterogeneous disease with varied response to therapy. We examined predictors of remission at one year among patients with PsA initiating a TNF inhibitor (TNFi).

Methods: Patients with PsA enrolled in the Corrona Registry between 2005-2013 with were followed from initiation of a TNFi (etanercept, adalimumab, infliximab, certolizumab, or golimumab) to the visit closest to 12 months from therapy initiation.  The outcome of interest was Clinical Disease Activity Index (CDAI) ≤ 2.8 at one year (remission).  Given concern about use of the 28-joint count in PsA patients with low joint counts, patients were required to have at least three tender or swollen joints for inclusion. Covariates of interest included baseline demographics (e.g., age, gender, work status), disease manifestations (e.g., enthesitis, dactylitis), patient reported outcomes (e.g., pain, fatigue, function), comorbidities (e.g., hypertension, diabetes), concurrent therapy (methotrexate, NSAIDs, glucocorticoids), and previous biologic use.  Univariable associations between covariates and achieving remission at 12 months were tested.  Covariates with p-value ≤0.10 and ≤10 missing values were included in a multivariable logistic regression model and removed individually until all remaining variables were significant (p<0.05).

Results: Among 1742 TNFi initiations, 725 patients met inclusion/exclusion criteria. Mean age at therapy initiation was 51.5 (SD 12.3) and 56% were female.  Mean baseline CDAI was 20 (IQR 14.5-28), median PsA duration was 5 years (IQR 2-11), and 36% had erosions at baseline. The outcome (CDAI≤ 2.8) was achieved by 17% (N=121). Baseline characteristics and differences by outcome are shown in Table 1.  In the multivariable model (Table 2), working full time was positively associated with achieving remission (OR 2.30, 95%CI: 1.44-3.68) and baseline pain (OR 0.98 per unit increase in 100 mm VAS), body mass index (OR 0.95 per unit increase, 0.92-0.98), female sex (OR 0.64, 0.41-0.99), previous biologic use (OR 0.58, 0.38-0.90), and baseline CDAI (OR 0.97 per unit increase, 0.95-0.99) were negatively associated with achieving remission.

Conclusion:   Among PsA patients initiating a TNFi, ≤25% achieved remission by 12 months. Female gender and higher pain and global scores were previously linked to switching therapies and obesity was associated with lower likelihood of achieving remission; we confirm these findings in this multicenter study representative of care in the US.  This is the first study to report that working full time was associated with remission.