Performance in the Centers for Medicare & Medicaid Services’ Hospital-acquired Conditions Reduction Program is heavily influenced by hospital size, according to a new study in the American Journal of Medical Quality. Researchers from the AHA, KNG Health Consulting, the Network for Excellence in Health Innovation and the Association of American Medical Colleges examined component measures of the Patient Safety Indicator 90, a composite measure intended to reflect performance on multiple types of complications. The authors simulated hospitals’ likelihood of being in the worst-performing quartile on each measure assuming identical expected complication across hospitals and found that “variations across hospitals in numbers of cases can bias the results.” According to the study, the direction of the bias depends on the expected complication rate and the distribution of eligible cases across hospitals. “Large hospitals, compared with smaller hospitals, are more likely to be identified as poor performers for measures with very low probabilities of complication. The reverse holds for measures with higher probabilities of complication,” the authors note. In an AHA Stat blog post today, Nancy Foster, AHA vice president for quality and patient safety policy, wrote, “The way the law and CMS’s regulations set up the HAC program unfairly penalizes hospitals at both ends of the spectrum – both the larger and smaller ones,” noting that “penalties on the HAC program are more a function of math than of true underlying quality.”