Positive predictive value of the AHRQ Patient Safety Indicator "postoperative wound dehiscence"

The Agency for Healthcare Research and Quality patient safety indicator (PSI) 14, or "postoperative wound dehiscence," is 1 of 4 PSIs recently adopted by the Centers for Medicare & Medicaid Services to compare quality and safety across hospitals. We determined how well it identifies true cases of postoperative wound dehiscence by examining its positive predictive value (PPV).

A retrospective cross-sectional study of hospitalization records that met PSI 14 criteria was conducted within the Veterans Health Administration hospitals from fiscal years 2003 to 2007. Trained abstractors used standardized abstraction instruments to review electronic medical records. We determined the PPV of the indicator and performed descriptive analyses of cases.

Of the 112 reviewed cases, 97 were true events of postoperative wound dehiscence, yielding a PPV of 87% (95% CI 79% to 92%). Sixty-one percent (n = 59) of true positive cases had at least 1 risk factor, such as low albumin level, COPD, or superficial wound infection. False positives were due to coding errors, such as cases in which the patient's abdomen was intentionally left open during the index procedure.

PSI 14 has relatively good predictive ability to identify true cases of postoperative wound dehiscence. It has the highest PPV among all PSIs evaluated within the Veterans Health Administration system. Inaccurate coding was the reason for false positives. Providing additional training to medical coders could potentially improve the PPV of this indicator. At present, this PSI is a promising measure for both quality improvement and performance measurement; however, its use in pay-for-performance efforts seems premature.