Abstract
ABSTRACTOBJECTIVEThe objective of this study is to estimate the attrition rates and evaluate factors associated with loss to follow-up between 1994 and 2011 in an open cohort of HIV-negative men who have sex with men.METHODSThe Project Horizonte is an open cohort study that aimed to assess the incidence of HIV infection, evaluate the impact of educational interventions, and identify potential volunteers for HIV vaccine trials. The rates of losses to follow-up were estimated for three periods (1994–1999, 2000–2005, and 2006–2011). The variables analyzed were collected in a psychosocial questionnaire. Volunteers who dropped out were compared with the ones who remained in the study using a Cox regression model.RESULTSA total of 1,197 volunteers were recruited. The median follow-up time in the study (n = 626) was 4.2 years. The median follow-up time for the volunteers who dropped out of the study (n = 571) was 1.46 years. The overall rate of loss to follow-up was 11.6/100 person-years. Attrition rates by period were: 12.60 (1994–1999), 11.80 (2000–2005), and 9.00 (2006–2011) per 100 person-years. Factors associated with losses to follow-up were: age group of 21–30 years old, monthly per capita income of more than six or less than one Brazilian minimum wage, having more than two dependents, report of bisexual practice, and inconsistent use of condoms for receptive anal sex.CONCLUSIONSA slight decrease of the loss to follow-up was observed over time. Higher attrition rates happened in the first three years of follow-up. It is possible that the link of the volunteers were not yet well established. Those who reported inconsistent condom use in receptive anal sex were more likely to leave the study, suggesting an underestimation of the incidence of HIV infection in a cohort population. For greater effectiveness, retention strategies must be reassessed considering the connection between the characteristics of homosexual and bisexual behavior and the motivations to engage in health research.
Highlights
It is estimated that 686,478 individuals were living with HIV/AIDS in Brazil in 2012, which represents a prevalence rate of 0.4% of the population
A slight decrease of the loss to follow-up was observed over time
This study aimed to estimate the attrition rates during follow-up and evaluate factors associated with loss to follow-up among men who have sex with men (MSM) enrolled in the Project Horizonte in the period between 1994 and 2011
Summary
It is estimated that 686,478 individuals were living with HIV/AIDS in Brazil in 2012, which represents a prevalence rate of 0.4% of the population. The epidemic in the country is concentrated in populations at higher risk of HIV exposure, including sex workers, injecting drug users, and men who have sex with men (MSM). The Project Horizonte was an open cohort study of MSM, established in Belo Horizonte, State of Minas Gerais State, Brazil, in 1994. The objectives of the Project Horizonte were to establish and follow a HIV-negative MSM open cohort to (i) evaluate the feasibility of following such a cohort for an extended period of time, (ii) determine HIV incidence, (iii) evaluate counseling and educational practices for reducing risk, (iv) evaluate the possibility of conducting clinical trials of preventive HIV vaccines with cohort members, and (v) discuss ethical and technical aspects of clinical trials with preventive HIV vaccines. The Project Horizonte is the single running cohort of HIV-negative MSM in Brazil[2]
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