Damage indices in rheumatic diseases: A systematic review of the literature.

OBJECTIVE: To review the current literature, and evaluate the psychometric properties of disease damage indices in rheumatic diseases.

METHODS: A search of Medline, EMBASE, and Cochrane Library databases was performed to June 2018 to identify damage indices in all systemic rheumatic diseases. Articles were included in a systematic review if indices were composite (multi-organ) in nature and if adequate detail on methodology was described. Articles pertaining to the validation of these indices were also reviewed in order to assess the psychometric properties of the indices using the Outcome Measures in Rheumatology Arthritis Clinical Trials (OMERACT) filter as a guide.

RESULTS: Of the 2659 articles retrieved through the search, we identified 7 damage indices in five diseases: idiopathic inflammatory myopathy, systemic lupus erythematosus, systemic vasculitis, Sjӧgren's syndrome and antiphospholipid syndrome. A further 48 articles were identified pertaining to the validation of these damage indices. The methodological process for the development of these indices included expert consensus, item reduction and item weighting methods. The level of validation that these indices have achieved is variable, with only 2 damage indices fulfilling all criteria of the OMERACT filter.

CONCLUSIONS: To date, there have been 7 composite disease damage indices created in a variety of rheumatic diseases, with the exception of systemic sclerosis (SSc). This review has informed methodology for the development of a disease damage index in SSc.