OBJECTIVES: To estimate incremental resource use and costs of Pso and obesity in Pso patients. METHODS: Adult Pso patients (≥2 Pso diagnoses) were selected from a large US claims database (2004-2008). Pso patients were matched (based on age and gender) to Pso-free patients (i.e., without Pso or psoriatic arthritis diagnosis). Obesity was defined based on patients’ reported body mass index (BMI≥30). Healthcare resource use and costs were assessed over a one-year period. Incidence rate differences and incremental annual total health care costs (USD 2010; measured from a payer perspective) associated with Pso and obesity between Pso and Pso-free patients were estimated using multivariate Poisson regression models and generalized linear regression models, respectively, controlling for age, gender, and Charlson comorbidity index. RESULTS: A total of 1874 matched pairs with reported BMI were selected. Among Pso patients, 34% were obese compared to 28% of the Pso-free controls (p<0.01). Compared to non-obese Pso patients, obese Pso patients had on average 7 more urgent care visits (hospitalizations and emergency department visits) per 100 patient-years (p =0.02), and 1.8 more outpatient visits per patient-years (p =0.01). Compared to Pso-free patients, Pso was associated with 5.0 more outpatients visits per patient-years in non-obese patients and 6.3 more outpatients visits per patient-year in obese patients (both p <0.01). Among Pso patients, obesity presented a $2,729 incremental cost compared to the non-obese Pso patients ($12,670 vs. $9,192; p<0.01). Compared to Pso-free patients, Pso was associated with a $4,735 incremental total health care cost among non-obese patients ($9,192 vs. $4,681; p<0.01) and a $6,887 incremental cost among obese patients ($12,670 vs. $5,460; p<0.01). The difference ($2152) between $6887 and $4735 was not statistically significant in the final model. CONCLUSIONS: Pso patients have higher prevalence of obesity when compared to Pso-free patients. Both Pso and obesity were associated with significant incremental costs.