Effect of volume on total hip arthroplasty revision rates in the United States Medicare population.

BACKGROUND: Fewer short-term complications following total hip arthroplasty have been associated with greater hospital and surgeon procedure volume. It remains unclear if procedure volume is associated with longer-term clinical outcomes and revision rates. We examined the association between hospital and surgeon procedure volume and total hip arthroplasty revision rates in the Medicare population at six months to eight years postoperatively.
METHODS: A subset of the 1997 to 2004 Medicare claims data was used to identify primary and revision total hip arthroplasties. The Kaplan-Meier method and Cox regression analysis were used to determine revision rates and hazard ratios associated with hospital and surgeon procedure volumes at 0.5, two, five, and eight years postoperatively.
RESULTS: About one-third of the primary hip procedures were done at hospitals with the highest annual volumes of total hip arthroplasties (more than 100). Surgeons with an annual volume of more than fifty procedures performed approximately one-sixth of the primary total hip arthroplasties. Patients who had been operated on by these surgeons had a lower revision rate at six months than did patients treated by surgeons with an annual volume of six to ten or eleven to twenty-five procedures (adjusted hazards ratio, 1.67 and 1.63, respectively). There was no effect of surgeon volume at the time of longer-term follow-up.
CONCLUSIONS: The majority of the total hip arthroplasties in the Medicare population from 1997 to 2004 were not performed by the highest-volume hospitals or surgeons. Our findings suggest that patients of low-volume surgeons have a greater risk of arthroplasty revision at six months but no greater risk of revision at the time of longer-term follow-up. There appeared to be no significant association between hospital volume and the rate of revisions of total hip arthroplasties.