OP0022 PREDICTORS OF UNSATISFACTORY PATIENT-RELEVANT OUTCOME AFTER TOTAL HIP REPLACEMENT FOR OSTEOARTHRITIS
A.K. Nilsdotter, I.F. Petersson, E.M. Roos, S.L. Lohmander

Methods: This prospective study investigated if predictors of unsatisfactory outcomes after unilateral total hip replacement (THR) could be identified. Responses to the SF-36 and WOMAC questionnaires from 219 patients with a unilateral THR were compared to the responses from a reference group of 117 age, sex and municipality matched individuals. Follow up was done at 3.6 years.

Results: 94% (n=198) of the THR patients and 76% (n=83) of the reference group participated in the follow up. No differences between the patients and the reference group in any of the SF-36 subscales except physical function where the patients scored worse (60 vs. 71, p=< 0.0001). The patients also reported worse WOMAC pain (82 vs. 87, p=0.006) and poorer WOMAC function (74 vs. 84, p=>0.0001) than the reference group.

When the postoperative WOMAC score was compared to the preoperative score in the THR group, 31% improved less than 10 of 100 points for pain and/or function at the 3.6 year follow up. A higher degree of pain preoperatively (OR 0.97 CI 0.94-0.99) and age (OR 1.09 CI 1.03-1.15) predicted a worse outcome in WOMAC function postoperatively (OR expressed per one year or scale unit increase).

Editorial Comments: This is a well-designed prospective study in an under-investigated area (total hip arthroplasty). Because of the high rate of disability with advancing age, it was important to have an age-matched control group. Post-hip arthroplasty patients had modestly worse functional and pain outcomes but quality of life overall was otherwise comparable. One potential methodological problem is the high dropout rate in the reference group, 24%, compared to the patient group, 6.7%.

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