The PrEP GAT Almada Cohort Study: a cross-sectional description of the first participants

Abstract

Introduction: Pre-exposure prophylaxis (PrEP) was a significant advance in HIV prevention as it reduces the risk of HIV by 99%. However, retention in PrEP care remains a key challenge. To monitor and evaluate PrEP delivery, the World Health Organization proposed a model of PrEP Cascade consisting of a cyclic care continuum that provides a comprehensive view of PrEP candidates' and users' journey through PrEP care. In this context, the Institute of Public Health of the University of Porto and GAT Almada collaborated to establish the PrEP GAT Almada Cohort, aiming to investigate factors influencing retention in care throughout the PrEP cascade proposed by the WHO. Objectives: This thesis aimed to detail the setup and design of the PrEP GAT Almada cohort and to present a descriptive analysis of its first participants' characteristics at recruitment, from the period between February 8th, 2024, and July 4th, 2024. Methods: The PrEP GAT Almada Cohort is an observational ambispective study following participants from enrollment in PrEP to 6 months from recruitment. Self-administered structured questionnaires were designed to be completed at recruitment and 6-month follow-up. The cohort includes PrEP candidates (on the waiting list) and beneficiaries (attending consultations) at GAT Almada, aged over 18 and able to complete the questionnaire in Portuguese. This thesis presents preliminary baseline data from participants recruited from February 8th to July 4th, 2024. Of the 224 patients attending PrEP consultations, 115 were approached, 111 were eligible, and 107 agreed to participate. Among these, 81 completed the baseline questionnaire. Participants were categorized based on their phase in the PrEP cascade at the time of recruitment (first consultation, second consultation or follow-up). Categorical variables were reported as frequencies and proportions, while continuous variables were summarized using means, standard deviations, medians, and interquartile ranges. Sociodemographic characteristics were stratified by questionnaire completion status. Other variables, such as behavior, beliefs about PrEP and HIV, and adherence, were stratified by the phase in the PrEP cascade. Missing data were excluded from item-specific analyses. Results: Participants were mostly cisgender men, aged 25-34 years, identifying as gay/homosexual, with high educational attainment and full-time employment. Most were born in Brazil, followed by Portugal, and resided in the latter. Participants with complete and incomplete questionnaires showed similar characteristics. Most participants agreed that PrEP effectively reduces HIV risk; concerns about PrEP-related stigma were low, and slightly more than one-third were concerned about side effects. Pre-PrEP participants reported higher condom use and other prevention measures, while PrEP users primarily relied on PrEP alone. Mean out-of-pocket expenses for a PrEP appointment were 9.90 € (SD 12.9). Satisfaction with PrEP services was overall high (95.5% satisfied or very satisfied). It was highest regarding relationships with healthcare professionals (97.7%) and lowest for medication dispensing (52.3%). Forgetfulness was the most common reason for missing doses (65.1%). Conclusion: The PrEP GAT Almada Cohort study provides valuable insights into the characteristics, behaviors, and attitudes of PrEP users in Portugal, offering a perspective on PrEP implementation outside the traditional hospital-based model. The study highlights strong confidence in PrEP efficacy, which is an important individual-level factor for successful PrEP programs. However, it also uncovers potential areas of concern, such as lower satisfaction with structural-level aspects like medication dispensing and appointment scheduling, which may potentially impact follow-up adherence. The overall high satisfaction rates with PrEP services suggest that the community-based model implemented by GAT Almada is well-received. This could inform future strategies for PrEP delivery and expansion of services. While this cohort may not be fully representative of the entire population on PrEP in Portugal, it provides critical data for monitoring HIV prevention efforts, namely regarding factors influencing retention in care throughout the PrEP cascade.