Anesthesiologists Are Affiliated with Many Hospitals Only Reporting Anesthesia Claims Using Modifier QZ for Medicare Claims in 2013

We examined hospitals that exclusively used the billing modifier QZ in anesthesia claims for a 5% sample of Medicare beneficiaries in 2013. We used a national Medicare provider file to identify physician anesthesiologists and nurse anesthetists affiliated with these hospitals. Among the 538 hospitals that exclusively reported the modifier QZ, 47.5% had affiliated physician anesthesiologists. These hospitals accounted for 60.4% of the cases. Our results illustrate the challenges of using modifier QZ to describe anesthesia practice arrangements in hospitals. The modifier QZ does not seem to be a valid surrogate for no anesthesiologist being involved in the care provided.