AAOS 2009: Certain Factors Increase Risk for Death After Total Hip Arthroplasty

Barbara Boughton

March 03, 2009

March 3, 2009 (Las Vegas, Nevada) — Total joint-replacement surgery for acute hip fracture is more likely to lead to death than the same surgery done on an elective basis, according to a single-institution analysis presented here at the American Academy of Orthopaedic Surgeons (AAOS) 2009 Annual Meeting.

Patient comorbidities, overall health, and delay before surgery are also important predictors of mortality 30 days after total hip arthroplasty (THA), according to Fernando Martin Comba, MD, from Buenos Aires, Argentina. Aggressive prophylaxis for thromboembolism did not affect the risk for death, he said.

In the retrospective case–control study, data from 3232 primary THAs performed in 1 Buenos Aires hospital between May 1993 and May 2006 were analyzed. All patients had at least 1 month of follow-up. Of the procedures, 75% were elective and 25% were nonelective, occurring after hip fracture. The study was a 4 to 1 case–control analysis, meaning that data from 4 living patients were compared with data from each patient who died. Both groups were carefully matched for patient characteristics.

The overall mortality rate from THAs in the 13-year period was 0.34%. Those receiving nonelective surgery after hip fracture had a higher mortality rate (1.15%) than those receiving elective procedures (0.08%). "Most data we have on mortality from THAs come from centers in the United States and Europe. But the rates we found did not differ significantly from those reported in previous studies," Dr. Comba said.

Elective surgery was associated with a lower risk for mortality than nonelective surgery after hip fracture, with an odds ratio (OR) of 0.07 (95% confidence interval [CI], 0.008–0.600; P = .015). Comorbidities might have contributed to the higher death rate among patients who had nonelective surgery and to more toxicity from the bone cement fixation, Dr. Comba commented.

The most important reasons for death were cardiac events and pulmonary embolism. However, the use of aggressive prophylaxis medications did not affect the death rate, compared with less aggressive regimens, such as aspirin, Dr. Comba said. Neither the number of blood transfusions nor the amount of blood loss during surgery affected the risk of dying among THA patients, he added.

An American Society of Anesthesiologists score of III to IV increased mortality risk 13 times (OR, 13.7; 95% CI, 1.6–114.8), and cardiovascular disease elevated the risk of dying 8 times (OR, 8.83; 95% CI, 1.78–43.6), according to the researchers. A delay of more than 3 days before surgery was also significantly associated with an increased risk for mortality (P = .06), a trend that has been seen in other studies, Dr. Comba said.

He noted that the study was limited by its retrospective nature, but it identifies risk factors that could help alert surgeons to patients at increased risk for mortality after THA. "Ideally, we could perform stricter management of patients having THA to reduce the risk of mortality," he said.

"This study really looked at 2 patient groups — those who had total hip arthroplasty for fracture and those who had elective total hip replacement," said Jay Mabrey, MD, who moderated the session at which the study was presented. Dr. Mabrey is a fellow of the AAOS and chief of orthopaedics at Baylor Medical Center, in Dallas, Texas. "As death was the primary end point, we can only conclude that THA for acute fracture carries a greater risk of death."

Dr. Mabrey commented that he would have liked to see more data on mortality after THA, compared with other methods of treatment for hip fracture. "I would have liked to see a comparison of hip fractures treated by other means, such as dynamic hip screw or intramedullary hip screw," he said.

Dr. Comba disclosed no relevant financial relationships. Dr. Mabrey disclosed consultant fees from Exactech, Inc, and research support from Synthes.

American Academy of Orthopaedic Surgeons (AAOS) 2009 Annual Meeting: Abstract 496. Presented February 27, 2009.

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