title: Treatment patterns and health care costs for patients with psoriatic arthritis on biologic therapy: a retrospective cohort study.
abstract: BACKGROUND
  Biologic therapies have been used in patients with psoriatic arthritis (PsA) who have been inadequately treated with conventional disease-modifying anti-rheumatic drugs (DMARDs).
  
  
  OBJECTIVE
  Examine treatment patterns and health care costs among patients with PsAs who initiated biologic therapy either as monotherapy or adjunctively with traditional DMARDs.
  
  
  METHODS
  The MarketScan(®) database was used to identify adults with PsA who initiated therapy with a biologic (with first use identified as index date). Patients were required to have a 6-month pre-period with no biologic use and 1 year insurance eligibility pre- and post-index date. Cohorts of patients initiating biologic therapy either as monotherapy or adjunctively with traditional DMARDs were created. Medication use patterns including discontinuation, switching, and restarting were identified during the 1-year follow-up period. Cox proportional hazards models were conducted to compare time to discontinuation of index biologic, and logistic models were used to compare the rate of discontinuation and biologic switching between the 2 cohorts. All-cause and PsA-related costs were compared between the 2 cohorts using propensity score-adjusted bootstrapping methods. All comparisons were made after adjusting for age, sex, Charlson comorbidity index, and PsA-related total cost over 1-year pre-index date.
  
  
  RESULTS
  Among the 3164 PsA patients identified, 67.7% initiated biologics as monotherapy and 32.3% initiated biologics adjunctively with traditional DMARDs. The number of patients on pain medications, topical medications, and traditional DMARDs was significantly lower post index date compared to pre-index date (P < 0.01), while use of antihypertensives, antidiabetics, and statins increased after patients initiated biologic therapy. In 1-year post-period, approximately half of the patients (50.9%) who initiated a biologic continued their index biologic with an average time to discontinuation of 279.8 days for all patients. Rates of discontinuation, switching, and restart were 33.1%, 9.9%, and 6.1%, respectively, for all patients. Rates of switching and restart were similar between the 2 cohorts, but a significantly lower rate of discontinuation was observed in the biologic plus traditional DMARDs cohort than the biologic monotherapy cohort. Pharmacy expenditures were higher for the biologic + DMARD cohort than the biologic-monotherapy cohort ($14,486 vs $14,062; P = 0.0348). No statistically significant differences for either all-cause or PsA-specific costs were observed across the treatment cohorts.
  
  
  CONCLUSIONS
  Traditional DMARDs used in combination with biologic therapy appear to reduce rates of biologic therapy discontinuation.
authors: Eli Lilly and Company, Indianapolis, Indiana.
authors: Baojin
authors: B
authors: Zhu
authors: Emily
authors: E
authors: Edson-Heredia
authors: Jennifer L
authors: JL
authors: Gatz
authors: Jiaying
authors: J
authors: Guo
authors: Catherine L
authors: CL
authors: Shuler
mesh_terms: D000328:Adult; D000368:Aged; D018501:Antirheumatic Agents / Q000191:economics / Q000627:therapeutic use*; D015535:Arthritis, Psoriatic / Q000188:drug therapy* / Q000191:economics; D001691:Biological Therapy / Q000191:economics*; D015331:Cohort Studies; D016208:Databases, Factual; D016527:Drug Costs; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D010349:Patient Compliance; D012189:Retrospective Studies
chemical_list: D018501:Antirheumatic Agents
keywords: biologics; disease modifying anti-rheumatic drugs; medical expenditures; psoriatic arthritis; treatment patterns