title: A case-control study of anaemia in patients with rheumatoid arthritis treated with disease-modifying antirheumatic drugs in an adult population in the US: prevalence and impact on healthcare utilisation.
abstract: OBJECTIVE
  The objective of this study was to estimate the prevalence of anaemia and its impact on healthcare utilisation in patients with rheumatoid arthritis (RA).
  
  
  METHODS
  Patients with claims for moderate-to-severe RA (ICD-9 code 714.x) treated with disease-modifying antirheumatic drugs as well as controls without RA matched for age, gender and time in plan were selected from the MarketScan Research Database. Anaemia was identified by ICD-9 codes 280.x, 285.2x, 281.9, 285.9 and 284.8. The prevalence ratio and 95% confidence interval (CI) for anaemia among RA patients versus controls were estimated. Overall disease burden was measured using the Elixhauser Comorbidity Index (ECI).
  
  
  RESULTS
  The prevalence ratio for anaemia in RA patients was 2.2 (95% CI 2.1-2.4). Mean ECI was higher in RA (2.26) compared with control (1.02) patients (p<0.001), and RA patients with anaemia had a higher ECI compared with those without anaemia (3.95 vs. 2.08; p<0.001). Total healthcare costs in RA patients with anaemia were approximately twice those of RA patients without anaemia.
  
  
  CONCLUSIONS
  The prevalence of clinically diagnosed anaemia in RA patients in the claims database was 2.2 times higher than that in the comparable non-RA control group. RA patients with anaemia had significantly higher levels of co-morbidity and healthcare costs than RA patients without anaemia.
authors.affiliation: Worldwide Health Economics & Pricing, Johnson & Johnson Pharmaceutical Services, LLC, Malvern, PA, USA. chan3@cntus.jnj.com
authors.forename: Chenglong
authors.initials: C
authors.lastname: Han
authors.forename: Ning
authors.initials: N
authors.lastname: Zhao
authors.forename: Mahboob U
authors.initials: MU
authors.lastname: Rahman
authors.forename: Mittie K
authors.initials: MK
authors.lastname: Doyle
authors.forename: Mohan V
authors.initials: MV
authors.lastname: Bala
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000740:Anemia / Q000453:epidemiology*; D018501:Antirheumatic Agents; D001172:Arthritis, Rheumatoid / Q000188:drug therapy* / Q000453:epidemiology; D016022:Case-Control Studies; D005260:Female; D006296:Health Services / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D008875:Middle Aged; D014481:United States / Q000453:epidemiology
chemical_list: D018501:Antirheumatic Agents