Evaluation of Algorithms Used for PrEP Surveillance Using a Reference Population From New York City, July 2016–June 2018

Objective: Daily tenofovir disoproxil fumarate/emtricitabine (TDF/FTC) use as HIV preexposure prophylaxis (PrEP) is monitored by identifying TDF/FTC prescriptions from pharmacy databases and applying diagnosis codes and antiretroviral data to algorithms that exclude TDF/FTC prescribed for HIV postexposure prophylaxis (PEP), HIV treatment, and hepatitis B virus (HBV) treatment. We evaluated the accuracy of 3 algorithms used by the Centers for Disease Control and Prevention (CDC), Gilead Sciences, and the New York State Department of Health (NYSDOH) using a reference population in Bronx, New York. Methods: We extracted diagnosis codes and data on all antiretroviral prescriptions other than TDF/FTC from an electronic health record database for persons aged ≥16 prescribed TDF/FTC during July 2016–June 2018 at Montefiore Medical Center. We reviewed medical records to classify the true indication of first TDF/FTC use as PrEP, PEP, HIV treatment, or HBV treatment. We applied each algorithm to the reference population and compared the results with the medical record review. Results: Of 2862 patients included in the analysis, 694 used PrEP, 748 used PEP, 1407 received HIV treatment, and 13 received HBV treatment. The algorithms had high specificity (range: 98.4%-99.0%), but the sensitivity of the CDC algorithm using a PEP definition of TDF/FTC prescriptions ≤30 days was lower (80.3%) than the sensitivity of the algorithms developed by Gilead Sciences (94.7%) or NYSDOH (96.1%). Defining PEP as TDF/FTC prescriptions ≤28 days improved CDC algorithm performance (sensitivity, 95.8%; specificity, 98.8%). Conclusions: Adopting the definition of PEP as ≤28 days of TDF/FTC in the CDC algorithm should improve the accuracy of national PrEP surveillance.