The role of pain and functional impairment in the decision to recommend total joint replacement in hip and knee osteoarthritis: an international cross-sectional study of 1909 patients. Report of the OARSI-OMERACT Task Force on total joint replacement.

OBJECTIVE: To assess the pain and functional disability levels corresponding to an indication for total joint replacement (TJR) in hip and knee osteoarthritis (OA).

METHODS: International cross-sectional study in 10 countries.

PATIENTS: Consecutive outpatients with definite hip or knee OA attending an orthopaedic outpatient clinic. Gold standard measure for recommendation for TJR: Surgeon's decision that TJR is justified.

OUTCOME MEASURES: Pain (ICOAP: intermittent and constant osteoarthritis pain, 0-100) and functional impairment (HOOS-PS/KOOS-PS: Hip/Knee injury and Osteoarthritis Outcome Score Physical function Short-form, 0-100).

ANALYSES: Comparison of patients with vs without surgeons' indication for TJR. Receiver Operating Characteristic (ROC) curve analyses and logistic regression were applied to determine cut points of pain and disability defining recommendation for TJR.

RESULTS: In all, 1909 patients were included (1130 knee/779 hip OA). Mean age was 66.4 [standard deviation (SD) 10.9] years, 58.1% were women; 628/1130 (55.6%) knee OA and 574/779 (73.7%) hip OA patients were recommended for TJR. Although patients recommended for TJR (yes vs no) had worse symptom levels [pain, 55.5 (95% confidence interval 54.2, 56.8) vs. 44.9 (43.2, 46.6), and functional impairment, 59.8 (58.7, 60.9) vs. 50.9 (49.3, 52.4), respectively, both P<0.0001], there was substantial overlap in symptom levels between groups, even when adjusting for radiographic joint status. Thus, it was not possible to determine cut points for pain and function defining 'requirement for TJR'.

CONCLUSION: Although symptom levels were higher in patients recommended for TJR, pain and functional disability alone did not discriminate between those who were and were not considered to need TJR by the orthopaedic surgeon.