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

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.

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.

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%).

Adopting the definition of PEP as ≤28 days of TDF/FTC in the CDC algorithm should improve the accuracy of national PrEP surveillance.