title: Rheumatoid arthritis disease severity indices in administrative databases: a systematic review.
abstract: OBJECTIVE
  We aimed to systematically review rheumatoid arthritis (RA) disease severity indices for use in administrative healthcare databases. We also provide an overview of alternative methods to control for RA disease severity in administrative database research.
  
  
  METHODS
  We conducted a systematic review of studies that developed/validated an index for RA disease severity using variables in administrative databases, and compared the convergent validity/reliability of the index with a standard measure of RA severity.
  
  
  RESULTS
  After reviewing 539 articles, 2 studies were included. The claims-based index for RA severity (CIRAS) was developed in one study. Components of the CIRAS included tests for inflammatory markers, number of chemistry panels/platelet counts ordered, rheumatoid factor test, number of rehabilitation and rheumatology visits, and Felty's syndrome. The CIRAS correlated moderately well with a previously validated RA medical records-based index of severity. The second study assessed whether current and lifetime treatment with disease-modifying antirheumatic drugs and/or biologics accurately predicted RA severity, as measured by the patient-reported Patient Activity Scale (PAS). Treatment variables did not fully distinguish patients in the highest and lowest quartiles of PAS scores (67.2% correctly classified).
  
  
  CONCLUSIONS
  Two claims-based indices of RA severity were identified but have some limitations for routine use. A concerted effort from experts in the field is needed to define, develop, and validate a widely applicable measure of RA disease severity for administrative database research.
authors.affiliation: Montreal General Hospital, McGill University Health Centre, Montreal, Quebec H3G 1A4, Canada. evelyne.vinet@mail.mcgill.ca
authors.forename: Evelyne
authors.initials: E
authors.lastname: Vinet
authors.forename: Bindee
authors.initials: B
authors.lastname: Kuriya
authors.forename: Jessica
authors.initials: J
authors.lastname: Widdifield
authors.forename: Sasha
authors.initials: S
authors.lastname: Bernatsky
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001172:Arthritis, Rheumatoid / Q000175:diagnosis*; D003628:Database Management Systems / Q000592:standards*; D005260:Female; D006298:Health Services Administration / Q000592:standards*; D006801:Humans; D007344:Insurance Claim Reporting; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index