Rethinking procedural volume
Procedural volume is a perpetual sticking point in performance measurement, but is its form more controversial than its function?
In the medical staff realm, volume is typically expressed in whole numbers—the practitioner must perform so many procedures to qualify for clinical privileges or to satisfy established professional practice evaluation thresholds—but a new study published in the BMJ showcases a different approach. Rather than straight volume, researchers took a close look at a surgeon’s degree of specialization, hypothesizing that singular focus in a particular procedure may influence muscle memory, familiarity with the relevant medical device, transfer of granular knowledge and skills between cases, and other indications of surgical competence that can translate to better outcomes.
To quantify specialization, researchers created a relative, rather than absolute, measure: a percentage derived by dividing the number of times a surgeon performed a specific procedure (numerator) by his or her total operative volume (denominator). Using this formula, they found specialization to be “an important predictor of operative mortality independent of volume” in six common surgical procedures.
This line of research, although based on findings in other sectors and modeled after previous studies on procedural volume, broke new ground in surgical quality. “To the best of our knowledge, no study has described a statistical association between a surgeon’s degree of specialization in a specific procedure and patients’ mortality,” the researchers wrote.
For policy makers, this new perspective may provide fodder for initiatives targeting quality improvement in rural and small hospitals, whose operational circumstances can pose challenges for meeting absolute volume thresholds. For medical staff leaders, MSPs, and quality personnel, the lens presents new possibilities for privileging criteria and peer review performance indicators.
But for Benjamin D. Kozower, MD, MPH, professor of surgery at Washington University School of Medicine and a practicing thoracic surgeon, the study doesn’t do enough to assuage deep-seated doubts about the validity of volume-based performance metrics.
“It makes sense that the more specialized someone is and the more procedures someone does, the better the outcomes, and the vast majority of the literature supports that,” says Kozower, who’s been researching the relationship between procedural volume and surgical outcomes for the better part of a decade. “The problem is that the devil is in the details. The methodology that has been used to establish the volume-outcome relationship is very troubling.”