Patient Safety and Quality

Surgical risk score does not work well for knee and hip replacement operations

The Surgical Apgar Score calculates a patient's blood loss, lowest heart rate, and lowest mean arterial pressure during an operation to identify patients at risk for major complications or death within 30 days after surgery. While this score has been used for patients undergoing general and vascular surgery, a new study finds that it is not quite as useful for patients undergoing hip or knee replacement surgery.

Using medical records for 3,511 patients who had a hip or knee replaced from 2003 to 2006 at Massachusetts General Hospital, researchers calculated surgical Apgar scores. They found that the 10-point score was not able to comprehensively discriminate between patients who would and would not experience complications after undergoing those joint replacement surgeries. For instance, just 6.1 percent of patients who had major complications had an Apgar score of 4 or less, the range that indicates a high risk for complications. In fact, 78.6 percent of the patients who had complications had a score of 7 or higher, indicating low risk.

Even though the score was unable to predict complications, the authors say it does provide useful information for the post-op health care team on how well a surgery went and how the patient fared during the operation. This study was funded in part by the Agency for Healthcare Research and Quality (T32 HS00060).

See "The surgical Apgar score in hip and knee arthoplasty," by Thomas H. Wuerz, M.D., M.Sc., Scott E. Regenbogen, M.D., M.P.H., Jesse M. Ehrenfeld, M.D., and others in the April 2011 Clinical Orthopedics and Related Research 469(4), pp. 1119-1126.

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