Background and objective How patients respond to being notified of a large-scale adverse event (LSAE), such as improper sterilisation of medical equipment that exposes them to bloodborne pathogens, is not well known. The objective of this study was to determine, using administrative data, the intended and unintended consequences of patient notification following a LSAE.

Methods We examined five LSAEs where patients may have been inadvertently exposed to hepatitis C virus (HCV), HIV, and hepatitis B virus (HBV). A total of 9638 cases were identified at five Department of Veteran Affairs (VA) medical facilities between 2009 and 2012. We identified controls at the same facility prior to the exposure period and at neighbouring facilities (n=45 274). Difference-in-differences models were used with Veterans Health Administration (VHA) and Medicare data to examine infectious disease testing rates and subsequent utilisation patterns.

Results Receipt of a LSAE notification was associated with a 73.2, 76.8 and 77.1 adjusted percentage point increase for HCV, HIV and HBV testing, respectively (all p<0.001). Compared with white patients, African–American patients were significantly less likely to return to VHA for follow-up testing. Patients exposed to a dental LSAE reduced their use of preventive and restorative dental care over the subsequent year, but they eventually came back to VHA for dental services 18-months post exposure.

Conclusions The majority of patients notified of a LSAE responded by getting tested for HCV, HIV and HBV, although there remains room for improvement. Potential exposure to a LSAE was associated with increased odds of subsequently using non-VA facilities, but the size and timing of the shift depended on the type of care.