Current CDC Clinical Practice Guidelines for the provision of pre-exposure prophylaxis (PrEP) recommend screening for sexually transmitted infections (STI) only every 6 months, unless patients report symptoms. CDC’s 2015 STD Treatment Guidelines recommend STI screening for MSM every 3-6 months, but emphasize testing those with past STI history.
SPARK is a community-based PrEP demonstration project conducted at the largest LGBT health center in New York City. Patients prescribed PrEP are screened for urethral/rectal gonorrhea and chlamydia as well as syphilis every 3 months, and also visit the clinic for STI testing and treatment between study visits if they experience symptoms. STI data for patients in the 6-months prior to starting PrEP and in their first 12-months taking PrEP were abstracted from electronic medical records (EMR). We examined: a) the number and type of STIs that were diagnosed at each time point; b) diagnosis due to symptomatic patient presentation versus routine screening; and c) whether or not a positive STI at a previous time point would have triggered asymptomatic screening (absent the SPARK study protocol).
Among the 280 patients who began PrEP, 21% (n = 58) had an STI in the 6-months prior to starting PrEP (including 11% who tested positive for an STI at their PrEP prescription visit). At 3-month follow-up, 13% of patients were diagnosed with STIs, with 77% of these cases (10% of the total sample) resulting from routine screening, rather than symptomatic presentation. In addition, only 33% of patients with STIs at 3-month follow-up had a prior history of STI that would have triggered screening. At 9-month follow-up, 15% of patients were diagnosed with STIs, with 68% (10% of the total sample) diagnoses as a result of routine rather than symptomatic screening. Even though the percentage of patients with repeat STI diagnoses increased over time, basing STI screening on prior diagnosis at the 9-month visit would have missed 16% of STI cases. Overall, STI screening according to current CDC guidelines would have delayed diagnosis and treatment for 24% of PrEP patients, including 40 cases of rectal STI and 3 cases of syphilis.
Current CDC guidelines may miss a significant number of asymptomatic STI among PrEP users. STI screening may be particularly important at the first 3-month follow-up visit. Routine STI testing at each PrEP prescription visit appears warranted, with particular attention to those with past STI history.