SAN DIEGO – Even older, heavier, sicker patients, and those with worse mental health, benefit substantially from total hip replacement when indicated, a study has shown.
It’s just that their outcomes aren’t quite as good as those of their younger, leaner, and healthier peers because they also tend to start out with worse preoperative hip pain and function. Even so, they benefit about as much from the operation, gaining in the range of 20 points on the 48-point Oxford Hip Score (OHS), the study found.
Because of that, perhaps physicians should reconsider basing selection of surgery candidates on negative preoperative characteristics; maybe even "patient [body mass index (BMI)] should not be used, as these patients still get substantial improvement following surgery," lead investigator Andy Judge, Ph.D., said at the World Congress on Osteoarthritis, sponsored by Osteoarthritis Research Society International.
The team compared preoperative OHS scores with postoperative scores collected over a 5-year period from 1,375 hip replacement patients who underwent surgery because of osteoarthritis. Each got a cemented Exeter femoral component. Their mean age was 68; 60% were women.
The OHS asks patients 12 multiple-choice questions about pain and function. The five possible answers are scored 0-4, with 0 being the worst possible overall score, and 48 the best.
In general, and regardless of preoperative factors, surgery gave the majority of patients significant relief in the 1st year that was maintained through the 5th year, said Dr. Judge, a senior statistician at the University of Oxford.
There were "small differences in postoperative OHS observed for age, BMI, comorbidity, mental health, and femoral component size, but these patients still received substantial benefit from surgery," he said.
Preoperative hip pain and function was the biggest predictor of how patients fared after the operation. Patients with worse scores tended to have worse postoperative pain and function.
However, even those who entered the operating room with OHS scores below 5 improved, on average, to about 30. Those who entered with scores in the mid-30s improved to the low 40s.
Between-group magnitudes of improvement were similar for other factors taken into account. For instance, average preoperative OHS scores were in the lower teens for those with BMIs at or above 30 kg/m2; postoperative scores were in the mid-30s. Slimmer peers with BMIs below 30 kg/m2 entered the operating room with average OHS scores in the upper teens; their postoperative scores improved to about 40 on average.
It was the same story with poorer preoperative mental health scores and higher numbers of comorbidities; patients started and wound up a few points lower on the OHS, but tended to benefit about as much as patients with better mental health and fewer comorbidities.
Patients who were 60-70 years old had the best postoperative scores by a few points, but also started with OHS scores a few points higher than younger and older patients, who, nonetheless, had comparable, roughly 20-point improvements in postoperative OHS scores.
Similarly, patients with larger femoral component sizes (offset of 44 mm or more) also had slightly better outcomes, but also entered the trial with slightly better hip scores. The trial’s findings were statistically significant.
Dr. Judge said he had no relevant financial disclosures. The study was funded by the British National Institute for Health Research.