Patients' outcome after total hip arthroplasty: a comparison between the Western Ontario and McMaster Universities index and the Oxford 12-item hip score.

This prospective cohort study included 402 patients who had primary total hip arthroplasty. The Western Ontario and McMaster Universities Index (WOMAC) and the Oxford 12-item Hip Score (OHS) were used to assess patients preoperatively and at 1 year postoperation. The OHS has a higher responsiveness than the WOMAC in the global scale and in the pain subscale. However, the WOMAC has better responsiveness in its function scale. The point estimate of relative precision of measuring postoperative quality of life shows that the OHS has a tendency toward a better performance than the WOMAC; however, this finding is not statistically significant. The OHS also demonstrates similar floor and ceiling effect patterns as does the WOMAC. We recommend that the choice should depend on which scale researchers are using to power a study.