Determinants of adherence to daily PrEP measured as intracellular tenofovir diphosphate concentrations over 24 months of follow-up among men who have sex with men

Elshout, Mark A M van den; Hoornenborg, Elske; Coyer, Liza; Anderson, Peter L.; Davidovich, Udi; Vries, Henry J C de; Prins, Maria; Loeff, Maarten Schim van der

doi:10.1136/sextrans-2022-055499

Cited by 4 publications

(4 citation statements)

References 27 publications

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“…Furthermore, another behavior, and potential predictors of this behavior, that might be interesting to explore over time in future research among PrEP users is PrEP adherence. Previous studies in the Netherlands showed that adherence to daily and event-driven PrEP based on tenofovir diphosphate levels measured with dried blood spots was generally high (Jongen et al, 2021a , 2021b ; van den Elshout et al, 2023 ). They also found that several determinants, such as age and condomless anal sex with a casual partner, was associated with adherence, and that adherence may decrease over time (van den Elshout et al, 2023 ).…”

Section: Discussionmentioning

confidence: 98%

The Best Predictor of Future Behavior May Be the Past: Exploring Behavior Change in Men Who Have Sex with Men Using Pre-exposure Prophylaxis in the Netherlands

van Wees,

Coyer,

van den Elshout

et al. 2024

Arch Sex Behav

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Pre-exposure prophylaxis (PrEP) use prevents HIV transmission, and may lead to changes in sexual behavior. We aimed to explore sexual behavior over time, and identify predictors of behavior change in men who have sex with men (MSM) using PrEP at sexual health centers (SHC) in the Netherlands. We used longitudinal data from the national STI surveillance database (January 2018–June 2021) of HIV-negative MSM who first initiated PrEP in the national PrEP pilot. We modelled behavior change after PrEP initiation, and identified predictors of behavior change using multi-state Markov models. The probability of stopping group sex, chemsex, use of poppers or erection stimulants, and having ≥ 10 partners in the past 6 months among included MSM (n = 4,349, n SHC visits = 21,820) was higher compared to the probability of starting with these behaviors after PrEP initiation. However, MSM who used condoms consistently during anal sex had a high probability of changing to inconsistent condom use (0.8) at the next visit, and inconsistent condom users mostly remained inconsistent (0.8). First visit, visiting the SHC more often (vs. regular), and STI diagnosis were predictors of starting or continuing with most of the behaviors associated with increased risk. Behavior change was less likely among older participants (> 34 compared to ≤ 34 years), and during COVID-19 lockdown and post-lockdown periods compared to pre-COVID-19. Although condom use decreased over time, transitions towards stopping with other behaviors associated with increased likelihood of acquiring an STI after PrEP initiation were common. This may suggest increased sexual empowerment, especially among younger MSM. Predictors of behavior change may help to identify MSM who are likely to start with or continue to engage in these behaviors in the near future and to provide suitable and timely counselling about behavior and PrEP adherence.

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Section: Discussionmentioning

confidence: 98%

The Best Predictor of Future Behavior May Be the Past: Exploring Behavior Change in Men Who Have Sex with Men Using Pre-exposure Prophylaxis in the Netherlands

van Wees,

Coyer,

van den Elshout

et al. 2024

Arch Sex Behav

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“…These levels were also well above the protective thresholds at all time points up to 4 years after PrEP initiation in the majority of participants. A subgroup of participants was included in a nested RCT assessing the effect of an app providing visualised feedback to increase adherence, as reported previously [ 24 , 36 ], which could have possibly been a contributing factor to adherence. The absence of any HIV infection after 1 year on PrEP provides further evidence that PrEP use can be sustainable and efficacious in preventing HIV over the longer course.…”

Section: Discussionmentioning

confidence: 99%

Sexual behaviour and incidence of sexually transmitted infections among men who have sex with men (MSM) using daily and event-driven pre-exposure prophylaxis (PrEP): Four-year follow-up of the Amsterdam PrEP (AMPrEP) demonstration project cohort

van den Elshout,

Wijstma,

Boyd

et al. 2024

PLoS Med

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Background An increasing number of countries are currently implementing or scaling-up HIV pre-exposure prophylaxis (PrEP) care. With the introduction of PrEP, there was apprehension that condom use would decline and sexually transmitted infections (STIs) would increase. To inform sexual health counselling and STI screening programmes, we aimed to study sexual behaviour and STI incidence among men who have sex with men (MSM) and transgender women who use long-term daily or event-driven PrEP. Methods and findings The Amsterdam PrEP demonstration project (AMPrEP) was a prospective, closed cohort study, providing oral daily PrEP and event-driven PrEP to MSM and transgender women from 2015 to 2020. Participants could choose their PrEP regimen and could switch at each three-monthly visit. STI testing occurred at and, upon request, in-between 3-monthly study visits. We assessed changes in numbers of sex partners and condomless anal sex (CAS) acts with casual partners over time using negative binomial regression, adjusted for age. We assessed HIV incidence and changes in incidence rates (IRs) of any STI (i.e., chlamydia, gonorrhoea, or infectious syphilis) and individual STIs over time using Poisson regression, adjusted for age and testing frequency. A total of 367 participants (365 MSM) commenced PrEP and were followed for a median 3.9 years (interquartile range [IQR] = 3.4–4.0). Median age was 40 years (IQR = 32–48), 315 participants (85.8%) self-declared ethnicity as white and 280 (76.3%) had a university or university of applied sciences degree. Overall median number of sex partners (past 3 months) was 13 (IQR = 6–26) and decreased per additional year on PrEP (adjusted rate ratio [aRR] = 0.86/year, 95% confidence interval [CI] = 0.83–0.88). Overall median number of CAS acts with casual partners (past 3 months) was 10 (IQR = 3–20.5) and also decreased (aRR = 0.92/year, 95% CI = 0.88–0.97). We diagnosed any STI in 1,092 consultations during 1,258 person years, resulting in an IR of 87/100 person years (95% CI = 82–92). IRs of any STI did not increase over time for daily PrEP or event-driven PrEP users. Two daily PrEP users, and no event-driven PrEP users, were diagnosed with HIV during their first year on PrEP. Study limitations include censoring follow-up due to COVID-19 measures and an underrepresentation of younger, non-white, practically educated, and transgender individuals. Conclusions In this prospective cohort with a comparatively long follow-up period of 4 years, we observed very low HIV incidence and decreases in the numbers of casual sex partners and CAS acts over time. Although the STI incidence was high, it did not increase over time. Trial registration The study was registered at the Netherlands Trial Register (NL5413) https://www.onderzoekmetmensen.nl/en/trial/22706

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“…These levels were also well above the protective thresholds at all time points up to 4 years after PrEP initiation in the majority of participants. A subgroup of participants was included in a nested RCT assessing the effect of an app providing visualised feedback to increase adherence, as reported previously(23, 33), which could have possibly been a contributing factor to adherence. The absence of any HIV infection after one year on PrEP provides further evidence that PrEP use can be sustainable and efficacious in preventing HIV over the longer course.…”

Section: Discussionmentioning

confidence: 99%

Four years of PrEP use; sexual behaviour and STIs in the AMPrEP demonstration project cohort among men who have sex with men in Amsterdam, the Netherlands

Van Den Elshout,

Wijstma,

Boyd

et al. 2023

Preprint

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BackgroundAn increasing number of countries are currently implementing or scaling-up HIV pre-exposure prophylaxis (PrEP) care. With the introduction of PrEP, there was apprehension about possible risk compensation, particularly on the long term. To inform sexual health counselling and STI screening programmes, we aimed to study sexual behaviour and STI incidence among men who have sex with men (MSM) and transgender women who use long-term daily or event-driven PrEP.MethodsThe Amsterdam PrEP demonstration project (AMPrEP) provided oral daily PrEP and event-driven PrEP to MSM and transgender women in 2015-2020. Participants could choose their PrEP regimen, and could switch at each three-monthly visit. STI testing occurred at and, upon request, in-between 3-monthly study visits. We assessed changes in number of sex partners and condomless anal sex acts over time with casual partners (CAS) using negative binomial regression. We assessed changes in incidence rates (IR) of any STI (i.e., chlamydia, gonorrhoea, or infectious syphilis), individual STIs, and HIV over time using Poisson regression.Findings367 participants (365 MSM) commenced PrEP and were followed for a median 3.9 years (IQR=3.4-4.0). The number of sex partners decreased over time (adjusted rate ratio [aRR]=0.89/year, 95%CI=0.86-0.92), while the number of CAS acts with casual partners remained stable (aRR=0.98/year, 95%CI=0.94-1.01). IR of any STI was 87/100 person years (PY) (95%CI=82-93) and did not change over time for both daily PrEP or event-driven PrEP users. However, IRs of chlamydia and gonorrhoea decreased slightly in daily PrEP users. Two daily PrEP users, and no event-driven PrEP users, were diagnosed with HIV during their first year on PrEP.ConclusionWith no increase in the number of casual sex partners nor of CAS acts, we found no indication of possible risk compensation during the first four years of PrEP use. Although the STI incidence was high, it did not increase over time.FundingZonMw, RIVM, GGD, H-TEAM, Gilead.

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Determinants of adherence to daily PrEP measured as intracellular tenofovir diphosphate concentrations over 24 months of follow-up among men who have sex with men

Cited by 4 publications

References 27 publications

The Best Predictor of Future Behavior May Be the Past: Exploring Behavior Change in Men Who Have Sex with Men Using Pre-exposure Prophylaxis in the Netherlands

The Best Predictor of Future Behavior May Be the Past: Exploring Behavior Change in Men Who Have Sex with Men Using Pre-exposure Prophylaxis in the Netherlands

Sexual behaviour and incidence of sexually transmitted infections among men who have sex with men (MSM) using daily and event-driven pre-exposure prophylaxis (PrEP): Four-year follow-up of the Amsterdam PrEP (AMPrEP) demonstration project cohort

Four years of PrEP use; sexual behaviour and STIs in the AMPrEP demonstration project cohort among men who have sex with men in Amsterdam, the Netherlands

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