title: Merging Veterans Affairs rheumatoid arthritis registry and pharmacy data to assess methotrexate adherence and disease activity in clinical practice.
abstract: OBJECTIVE
  The Veterans Affairs (VA) Rheumatoid Arthritis (VARA) registry and the VA Pharmacy Benefits Management database were linked to determine the association of methotrexate (MTX) adherence with rheumatoid arthritis (RA) disease activity.
  
  
  METHODS
  For each patient, the medication possession ratio (MPR) was calculated for the first episode of MTX exposure of a duration of ≥12 weeks for both new and established MTX users. High MTX adherence was defined as an MPR ≥0.80 and low MTX adherence was defined as an MPR <0.80. For each patient, the mean Disease Activity Score with 28 joints (DAS28) score, erythrocyte sedimentation rate (ESR), and C-reaction protein (CRP) level observed during registry followup were compared in high- versus low-adherence groups.
  
  
  RESULTS
  In 455 RA patients, the prescribed doses of MTX (mean ± SD 16 ± 4 mg versus 16 ± 4 mg; P = 0.6) were similar in high-adherence patients (n = 370) in comparison to low-adherence patients (n = 85). However, the actual observed MTX doses taken by patients were significantly higher in the high-adherence group (mean ± SD 16 ± 5 mg versus 11 ± 3 mg; P < 0.001). DAS28 (mean ± SD 3.6 ± 1.2 versus 3.9 ± 1.5; P < 0.02), ESR (mean ± SD 24 ± 18 versus 29 ± 24 mm/hour; P = 0.05), and CRP level (mean ± SD 1.2 ± 1.3 versus 1.6 ± 1.5 mg/dl; P < 0.03) were lower in the high-adherence group compared to those with low MTX adherence. These variances were not explained by differences in baseline demographic features, concurrent treatments, or whether MTX was initiated before or after VARA enrollment.
  
  
  CONCLUSIONS
  High MTX adherence was associated with improved clinical outcomes in RA patients treated with MTX. Adjustment for potential confounders did not alter the estimated effect of adherence. These results demonstrate the advantages of being able to merge clinical observations with pharmacy databases to evaluate antirheumatic drugs in clinical practice.
authors: George E. Wahlen VA Medical Center and University of Utah, Salt Lake City, USA. grant.cannon@va.gov
authors: Grant W
authors: GW
authors: Cannon
authors: Ted R
authors: TR
authors: Mikuls
authors: Candace L
authors: CL
authors: Hayden
authors: Jian
authors: J
authors: Ying
authors: Jeffrey R
authors: JR
authors: Curtis
authors: Andreas M
authors: AM
authors: Reimold
authors: Liron
authors: L
authors: Caplan
authors: Gail S
authors: GS
authors: Kerr
authors: J Steuart
authors: JS
authors: Richards
authors: Dannette S
authors: DS
authors: Johnson
authors: Brian C
authors: BC
authors: Sauer
mesh_terms: D000368:Aged; D018501:Antirheumatic Agents / Q000627:therapeutic use*; D001172:Arthritis, Rheumatoid / Q000175:diagnosis / Q000188:drug therapy*; D057225:Data Mining; D005260:Female; D006801:Humans; D007356:Insurance, Pharmaceutical Services / Q000706:statistics & numerical data*; D008297:Male; D008727:Methotrexate / Q000627:therapeutic use*; D008875:Middle Aged; D015999:Multivariate Analysis; D057216:Propensity Score; D011446:Prospective Studies; D012042:Registries / Q000706:statistics & numerical data*; D012044:Regression Analysis; D012720:Severity of Illness Index; D013997:Time Factors; D016896:Treatment Outcome; D014481:United States; D014493:United States Department of Veterans Affairs / Q000706:statistics & numerical data*; D016903:Drug Monitoring
chemical_list: D018501:Antirheumatic Agents; D008727:Methotrexate