Volume not necessarily indicator of quality

Two studies that appear in the Jan. 14 issue of the Journal of the American Medical Association indicate that a high volume of procedures isn't an accurate indicator of positive outcomes.

A study by Rand Corp. found that hospitals treating the highest number of infants under three pounds at birth were not always the facilities with the lowest rate of infant deaths. The study at 332 hospitals over five years found that basing a referral system on volume standards would have saved an estimated 11 lives annually among the group, while basing referrals on historical mortality rates would have saved 115 lives-a 10-fold difference. The study concluded that direct measures based on patient outcomes are more useful quality indicators for the purposes of selective referral because they are better predictors of future mortality rates among providers and could save more lives.

A separate study by the Duke Clinical Research Institute considered the relationship between hospital volume and death rates for coronary artery bypass graft surgery.

Referring to the highest-volume hospitals would have averted 50 deaths in a study of 267,000 heart-bypass procedures in 2000 and 2001, less than 1 percent of the 7,110 deaths that occurred.

The study found wide variability in risk-adjusted mortality among hospitals of similar volume. It also identified many low-volume hospitals with low death rates and some high-volume centers with higher-than-expected mortality.

"Hospital volume had generally poor predictive accuracy as a means of identifying hospitals with significantly better or worse (bypass) mortality rates," wrote Eric Peterson, lead researcher on the study. Using volume as the sole basis of referrals would unfairly divert cases from nearly half of low-volume medical centers with outcomes equal to or better than overall death rates, he said.

This conclusion clearly contradicts proposals from the Centers for Medicare & Medicaid Services and the Leapfrog Group that suggest using hospital volume as an indicator of quality for this kind of surgery.
MHA Contact: Sandra Parker

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Volume not necessarily indicator of quality