The volume of total hip replacement (THR) surgeries done by an elderly patient's individual physician may be more important than the volume of THRs done at the hospital where the patient has the surgery, according to a recent study that was supported in part by the Agency for Healthcare Research and Quality (HS09775). Apparently, surgical volume by individual surgeons, not other surgeon-related characteristics or hospital characteristics, is the determining factor in the occurrence of postoperative orthopedic complications such as deep wound infection of the hip or dislocation of the prosthetic hip within 3 months after surgery.
The researchers analyzed Medicare claims data on 5,211 elderly patients (most of whom were white women) who underwent primary THR in 1995 or 1996 at 167 hospitals in three States, as well as data on hospitals and surgeons. They developed a model to determine whether hospital structure or surgeon-associated factors were at the root of the relationship between THR volume and postoperative orthopedic complications.
Of all the patients studied, nearly 3 percent suffered from an orthopedic complication after THR. Sixty-nine percent fewer complications occurred in hospitals that performed more than 100 THRs on Medicare patients each year, compared with hospitals that performed 25 or fewer THRs each year. However, when surgeon volume alone was added to the model, hospital volume was no longer significantly associated with complications.
After adjustment for patient-level and hospital-level characteristics (for example, dedicated orthopedic nursing unit), patients undergoing THR in low-volume hospitals whose surgeons performed 10 or more THRs per year on Medicare patients had a lower risk of complications compared with patients whose surgeons performed less than 10 THRs per year in the same hospitals. Similar surgeon-volume-related outcomes were found for patients in high-volume hospitals. In these models, characteristics of the hospital explained relatively little of the volume-outcome association. This finding suggests that the strategy of adapting prognostically favorable hospital characteristics may not improve outcomes in low-volume centers.
More details are in "Contribution of hospital characteristics to the volume-outcome relationship: Dislocation and infection following total hip replacement surgery," by Daniel H. Solomon, M.D., M.P.H., Elena Losina, Ph.D., John A. Baron, M.D., and others, in the September 2002 Arthritis & Rheumatism 46(9), pp. 2436-2444.
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