Patient characteristics that predict progression of knee osteoarthritis: a systematic review of prognostic studies.

OBJECTIVE: To identify, by systematic review, patient characteristics that can be used by health care practitioners to predict the likelihood of knee osteoarthritis (OA) progression.

METHODS: A search was conducted of the electronic databases Medline, EMBase, CINAHL, AMED, and Web of Science in November 2010. Two reviewers screened articles using inclusion/exclusion criteria. Study participants were adults with established knee OA. Outcome measures for disease progression were change in pain or function or deterioration in radiographic features. Included studies identified clinically relevant prognostic factors at baseline and reported a statistical association with outcome. Minimum followup was 1 year. Articles were assessed for bias, and strength of evidence was summarized for potential predictors of progression.

RESULTS: Thirty studies were included, of which 26 were of high quality. Age, varus knee alignment, presence of OA in multiple joints, and radiographic features had strong evidence as predictors of knee OA progression. Body mass index was a strong predictor for long-term progression (>3 years). Moderate participation in physical activity was not associated with progression. Numerous variables had limited or conflicting evidence.

CONCLUSION: Relatively few predictive variables have strong supporting evidence; numerous variables have limited or conflicting evidence. All variables with strong evidence can be easily evaluated and utilized in clinical practice. Existing knowledge should be developed in future research, particularly in cases where study numbers are low or findings are limited or conflicting. Standardized measurement of potential predictors and outcome measures is recommended.