The burden of illness associated with psoriasis: cost of treatment with systemic therapy and phototherapy in the US.

OBJECTIVE: To evaluate utilization and direct healthcare expenditures among psoriasis patients treated with systemic therapy and phototherapy in the United States. DESIGN: Cohort study using retrospective administrative medical claims. PATIENTS: Psoriasis patients treated with systemic therapy and phototherapy, as well as a matched cohort of non-psoriasis patients. All patients were covered by employer-sponsored insurance between 1 April 1996 and 31 December 2000. MAIN OUTCOME MEASURES: Estimated risk of hospitalization and total annual healthcare expenditures overall and by comorbidity status were compared for persons with psoriasis using systemic therapy or phototherapy and persons without psoriasis. Annualized utilization rates for hospitalizations, and use of emergency department, outpatient physician, outpatient laboratory, and outpatient pharmaceutical services were also compared across the two cohorts. RESULTS: Seventeen percent of psoriasis patients were treated with systemic therapy or phototherapy. Patients with comorbid anemia, carcinoma, diabetes, depression, GI disorders, hepatotoxicity, hypertension, and nephrotoxicity had significantly higher expenditures than non-psoriasis patients with the same comorbidities (p < or =0.05). Elevated risk of hospitalization also contributed to higher expenditures in patients treated with systemic therapy or phototherapy. Limitations of this study include those inherent in using claims data such as dependence on diagnosis coding, the fact that psoriasis severity cannot be determined directly from claims data, confounding comorbidities, and the fact that only direct healthcare expenditures were considered in this analysis. CONCLUSION: Psoriasis patients treated with systemic therapies/phototherapies have significantly more comorbidities and higher mean total healthcare expenditures compared to non-psoriasis patients. Psoriasis patients with selected comorbidities have significantly higher mean total healthcare expenditures compared to non-psoriasis persons with the same comorbidities.