Outcome Measures in Acute Gout: A Systematic Literature Review

Objective. Five core domains have been endorsed by Outcome Measures in Rheumatology (OMERACT) for acute gout: pain, joint swelling, joint tenderness, patient global assessment, and activity limitation. We evaluated instruments for these domains according to the OMERACT filter: truth, feasibility, and discrimination. Methods. A systematic search strategy for instruments used to measure the acute gout core domains was formulated. For each method, articles were assessed by 2 reviewers to summarize information according to the specific components of the OMERACT filter. Results. Seventy-seven articles and abstracts met the inclusion criteria. Pain was most frequently reported (76 studies, 20 instruments). The pain instruments used most often were 100 mm visual analog scale (VAS) and 5-point Likert scale. Both methods have high feasibility, face and content validity, and within- and between-group discrimination. Four-point Likert scales assessing index joint swelling and tenderness have been used in numerous acute gout studies; these instruments are feasible, with high face and content validity, and show within- and between-group discrimination. Five-point Patient Global Assessment of Response to Treatment (PGART) scales are feasible and valid, and show within- and between-group discrimination. Measures of activity limitations were infrequently reported, and insufficient data were available to make definite assessments of the instruments for this domain. Conclusion. Many different instruments have been used to assess the acute gout core domains. Pain VAS and 5-point Likert scales, 4-point Liken scales of index joint swelling and tenderness and 5-point PGART instruments meet the criteria for the OMERACT filter.