Prognostic factors on changes in pain, physical functioning and participation in patients with hip- and/or knee OA: A systematic review

OBJECTIVES: This study aims to systematically synthesize literature on prognostic factors of changes in either direction (i.e. worsening or improvement) in pain, physical functioning, and participation in patients with knee- and/or hip OA. METHODS: Studies included in two preceding reviews underwent full-text screening for inclusion in the current review. Additionally, an extensive literature search was conducted in five databases. Title/abstract screening was performed using an active learning program. Inclusion criteria comprised patients diagnosed with knee- and/or hip OA, with the dependent variable assessing pain, physical functioning, or participation. Potential associated prognostic factors were measured as independent variables. The methodological quality of studies was assessed with the Hayden criteria. RESULTS: Thirty one studies were included in this systematic review. In knee OA patients, pain worsening is associated with lower physical functioning (strong evidence) and with higher body mass index, ethnicity, and a higher comorbidity count (moderate evidence). Also in knee OA patients, pain improvement is associated with less pain at baseline (moderate evidence). In knee- and/or hip OA patients, worsening of physical functioning exhibited associations with higher body mass index, more pain, more hip pain, a higher comorbidity count, higher avoidance of activities (strong evidence), and ethnicity (moderate evidence). In knee OA patients, improvement in physical functioning showed an association with higher vitality (moderate evidence). Regarding the remaining prognostic factors there is weak, inconclusive, or inconsistent evidence for an association with the outcomes. In hip OA only weak evidence was found for three factors predicting a change in physical functioning. CONCLUSION: This review encompasses prognostic factors associated with changes in either direction (i.e., worsening or improvement) in pain, physical functioning and participation.. The results are consistent with other reviews. Future research should place a stronger emphasis on hip OA patients and participation as an outcome.