Although increases in the frequency of sexually transmitted infection (STI) screening may reduce the risk for delayed diagnoses and incident infection among HIV-positive individuals receiving pre-exposure prophylaxis (PrEP), the optimal screening frequency remains unknown. These study findings were published in International Journal of Infectious Diseases.
Researchers conducted a systemic review and meta-analysis to determine the optimal frequency of STI screening among patients with HIV infection receiving PrEP. Data for this study were sourced from 5 databases, and random-effects meta-regression models were used to calculate pooled estimates of STI test positivity in relation with screening frequency. Specific STIs that were screened for across the included studies were syphilis, gonorrhea, and chlamydia. Secondary outcomes included the rate of adherence to recommended STI screening frequency and changes in STI epidemiology.
A total of 46 studies were analyzed, of which 38 included data on STI screening frequency and 8 included data on secondary outcomes. The researchers noted that STI screenings at a frequency of 2- to 3-times monthly were more common among studies with data collected after 2015, those conducted in high-income countries, and those conducted among men who have sex with men (MSM).
In studies that evaluated the effects of 2 to 3 monthly STI screenings among patients in PrEP programs, the overall pooled positivity rates for Chlamydia, gonorrhea, and chlamydia were 0.20 (95% CI, 0.15-0.25), 0.17 (95% CI, 0.12-0.22), and 0.07 (95% CI, 0.05-0.08), respectively.
In regard to incident syphilis infection, no significant differences in pooled positivity were noted between studies that assessed the effects of 2- to 3- vs 4- to 6-times monthly STI screenings. Further analysis showed positivity rates for infection with chlamydia or gonorrhea were reduced by 50% and 75%, respectively, when STI screenings occurred 4- to 6- vs 2- to 3-times monthly.
Chlamydia positivity was significantly associated with the monthly frequency of STI screening and the year in which a study was conducted, whereas gonorrhea and syphilis positivity was associated with study duration and monthly STI screening frequency.
Data sourced from 631 MSM indicated consistent adherence to recommended STI screening frequency differed by screening site. The highest rates of adherence were noted among individuals who were screened via blood samples (87%), followed by those who were screened via urine (78%), pharyngeal (64%), and anorectal (57%) samples. Adherence rates were also higher among older vs younger individuals.
The researchers evaluated 2 modelling studies that assessed the effects of different STI screening frequencies among MSM following PrEP initiation. Results indicated that increasing STI screening frequency from 3- to 6-times monthly would reduce the combined incidence of gonorrhea and chlamydia (1.85 vs 0.93 per 100 person-years, respectively). However, results of a similar study indicated increasing the frequency of STI screening to 6-times monthly was not cost-effective.
Limitations of this analysis include the predominance of studies conducted in high-income countries, significant heterogeneity, and limited generalizability to non-MSM populations.
According to the researchers, “The increased costs and low adherence of screening for STIs more frequently than at every six months needs to be balanced against possible benefits, including implementation feasibility and AMR [antimicrobial resistance].”
Kim C-M, Zhao V, Mello MB, et al. Determining the screening frequency for sexually transmitted infections for people who use HIV pre-exposure prophylaxis: a systemic review and meta-analysis. Int J Infect Dis. Published online January 20, 2023. doi:10.1016/j.ijid.2023.01.007