Objective: To critically appraise the validity of activity indices used in the followup of patients with undifferentiated peripheral inflammatory arthritis (UPIA).
Methods: A systematic review was performed in Medline, Embase, the Cochrane Library, and abstracts presented at the 2007 and 2008 meetings of the American College of Rheumatology and European League Against Rheumatism. Selection criteria were: patients with UPIA, the assessment of instruments to evaluate disease activity, and assessment of validity of the instruments. Two reviewers screened titles and abstracts independently and collected data using ad hoc standard forms.
Results: The search yielded 179 articles and 834 abstracts, of which 4 articles and 1 abstract were included. We found no study that validated Disease Activity Score (DAS), Clinical Disease Activity Index (CDAI), or Simplified Disease Activity Index (SDAI). Included studies addressed validation of 4 questionnaires: WHO Disability Assessment Schedule (WHODAS), London Handicap Scale (LHS), Disease Repercussion Profile (DRP), and the Health Assessment Questionnaire (HAQ); and 3 indexes: RA Disease Activity Index (RADAI), McGill Range of Motion Index (McROMI), and NOAR Damaged Joint Count (NOAR-DJC). Questionnaires were self-administered and feasible; RADAI was the most feasible index. Internal consistency was studied in the questionnaires (Cronbach's α > 0.83). Responsiveness was tested in the DRP, LHS, and HAQ, but the approach to study sensitivity to change was poorly explained, with no clear intervention. Construct validity, examined by means of convergence with other instruments, was generally moderate, and slightly higher for the RADAI.
Conclusion: No instrument of disease activity has been fully validated for use in UPIA. We found no direct evidence of what is the most useful index to follow up patients with UPIA.