Improving the Evaluation of Low-Volume Hospitals

Low volume has been recognized as a problem when benchmarking hospitals due to outcome rate instability. We asked if low-volume hospital outcomes, using matching to control for many clinical and sociodemographic characteristics, would expose quality problems not observed with CMS methods.

Matched cohort study. Grades derive from mortality differences between all patients at the low-volume hospital and their matched controls.

Medicare patients admitted with Acute Myocardial Infarction, Heart Failure and Pneumonia in 78 low-volume Pennsylvania acute care hospitals (combined condition volume=75≤N≤750 for the 3 y, 2017-2019), using Medicare's Virtual Research Data Center.

Thirty-day mortality.

Using matching, 10 of 78 reportable low-volume hospitals had significantly higher mortality versus matched typical controls and 16 low-volume hospitals displayed significantly higher mortality versus well-resourced controls. In contrast, Medicare reported that only 3 of these same 78 hospitals had significantly higher mortality than "the national rate" on AMI, HF, or pneumonia.

We find that some low-volume hospitals performed well. Other low-volume hospitals had significantly worse outcomes than both well-resourced and typical hospitals; and some displayed significantly worse mortality compared with well-resourced controls but did not reach significant differences from typical controls. In short, performing "no different from the national rate," as is almost always reported for low-volume hospitals when using CMS methods, does not imply a low-volume hospital has acceptable outcomes. Reports based on matching can expose low-volume hospital quality problems not apparent using standard methods. Low-volume hospitals have more quality problems than generally reported.