Post-operative blood clot rates questioned as hospital quality measure

New research calls into question the validity of using post-operative blood clot rates as a metric of hospital quality. According to a study published Monday in the Journal of the American Medical Association, rates of venous thromboembolism—a term that includes pulmonary embolism and deep vein thrombosis—could be skewed by surveillance bias.

Such bias can occur in hospitals that have more expansive screening criteria for VTE, including the testing of asymptomatic patients, or in hospitals that rely more heavily on imaging for diagnosis, said the authors, who analyzed data from the CMS' Hospital Compare, the American Hospital Association and Medicare claims.

In other words, “the more you look, the more you find,” the study said.

The authors found that high-quality hospitals tended to adhere tightly to VTE prevention protocols but still had higher rates of VTE. Additionally, they found greater VTE rates at hospitals that used imaging to detect VTE. Such findings suggest “that VTE rates reflect the hospital staff's vigilance in looking for postoperative VTE, not true quality of care,” the study said.

The authors said their findings demonstrate that the measure “should likely not be used for accountability purposes in quality measurement.”

But the horse is already out of the barn. The VTE measure, Patient Safety Indicator 12, developed by the Agency for Healthcare Research and Quality, is already in use in a number of quality reporting programs, including several state-run improvement initiatives. And in 2015, the CMS will begin using VTE rates to determine hospitals' Medicare payments, as part of its value-based purchasing program.

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