Background/Purpose: Upadacitinib (UPA) 15 mg once daily (QD) has demonstrated efficacy and safety in patients with psoriatic arthritis (PsA) for up to 56 weeks in the Phase 3 SELECT-PsA 1 and 2 trials.1,2 This post hoc analysis of these studies explored the association of baseline characteristics and short-term responses with achievement of minimal disease activity (MDA) and Disease Activity Index for Psoriatic Arthritis (DAPSA) low disease activity (LDA). Methods: Data were pooled from patients with prior inadequate response or intolerance to ≥1 non-biologic (b) DMARDs (SELECT-PsA 1) or ≥1 bDMARDs (SELECT-PsA 2) originally randomized to UPA 15 mg QD. Logistic re-gression models were used to assess the association between baseline characteristics and short-term (Week 12) responses with achieving MDA or DAPSA LDA at 56 weeks, sustained MDA (MDA at Weeks 36 and 56), or sustained DAPSA LDA (DAPSA LDA at Weeks 36, 44, and 56). Each predictor was evaluated separately in an initial model that included effects for study and concurrent non-bDMARD use. Odds ratios and concordance (c-)statistics were used to determine the predictive accuracy. Statistically significant predictors were then evaluated simultaneously using stepwise logistic regression with the Akaike Information Criterion for model-building. Results: Of 640 patients included in the analysis, 40% and 47% achieved MDA and DAPSA LDA, respectively, at 56 weeks. Evaluated separately, younger age, sex (male), geographic region, lower weight, lower body mass index, the presence of dactylitis or enthesitis, and lower scores of Patient’s Assessment of Pain (Pt-Pain), Patient’s Global Assessment (PtGA), tender joint count in 68 joints, and Health Assessment Questionnaire-Disability Index (HAQ-DI) were significant baseline predictors for achieving MDA and DAPSA LDA at Week 56. Lower Pt-Pain (Weeks 12–24) and PtGA (Weeks 16–24) scores were strongly predictive (c-statistics >0.8) of achieving MDA at Week 56, and both measures (from Week 8) were moderately predictive (c-statistics >0.7) of achieving DAPSA LDA. Evaluated simultaneously with several baseline characteristics, lower Pt-Pain and HAQ-DI scores at Week 12 were included in models strongly predictive of achieving MDA (c-statistic=0.850; Figure 1) and DAPSA LDA (c-statistic=0.840; Figure 2) at Week 56. For each 1-point increase in Pt-Pain or HAQ-DI scores at Week 12 (after adjusting for other effects in the model), patients were less likely to achieve MDA (by 32% or 56%, respectively) or DAPSA LDA (by 23% or 31%, respectively) at Week 56. Predictors for achieving sustained MDA and sustained DAPSA LDA were generally similar to those identified for achieving MDA and DAPSA LDA, respectively. Conclusion: In patients with PsA receiving UPA 15 mg, baseline characteristics and early responses strongly predicted achievement of MDA or DAPSA LDA at Week 56. This may guide considerations of treatment targets in clinical trials and encourage physicians to further optimize treatment of their patients in clinical practice.