Estimation of the HIV Incidence and of the Number of People Living With HIV/AIDS in Brazil, 2012

The 12 city HIV Surveillance Survey among MSM in Brazil 2016 using respondent-driven sampling: a description of methods and RDS diagnostics

“…The incidence rate of AIDS cases among men 15 -19 and 20 -24 years of age increased from 3.7 to 6.9 and from 18.1 to 33.1 (/100,000) from 2008 to 2015 in the country 9 . While the estimated prevalence of HIV among the population of 15 years of age or older is 0.37% 10 , recent data suggest HIV rates of 4.9, 5.9, and 12.1% among users of injectable drugs, sex workers, and MSM, respectively [11][12][13] . These prevalence rates are 12, 15, and almost 30 times larger than in the general population.…”

Results from a Method for Estimating HIV Incidence Based on the First Cd4 Count among Treatment-Naïve Cases: Brazil, 2004-2013

“…Although the assumption that the square root of CD4 count is linearly related to time since infection has frequently been used in different settings [12,14,15], other types of functions have also been proposed [38,39]. In addition, Rice and collaborators have suggested that besides age at diagnosis, ethnicity and region of birth are significant predictors of rate of CD4 decrease [15].…”

“…Based on fitting a logistic distribution to the cumulative number of cases classified by intervals of time since infection, the procedure used in this study represents a simplification compared to the previous model [12], since it requires extrapolation of reported data over 5 years only. The proposed approach allowed us to estimate HIV incidence and 95% confidence limits by sex in the period 2004-2013, and the results are consistent with previous findings [12].…”

“…However, the expansion of antiretroviral therapy has lengthened the time to the onset of AIDS [10] making inferences about HIV incidence based on AIDS reported cases very limited. More recently, updates of back-calculation models relying on new HIV diagnoses have been applied for HIV incidence estimation [11][12][13][14][15]. One of the difficulties faced is to distinguish the contribution of changes in testing patterns in the trends of HIV reported cases [4].…”

“…Lately, methods based on the first CD4 count after HIV diagnosis have been developed to estimate HIV incidence in United Kingdom [4,15], France [11], Brazil [12] and United States [13,14]. The main assumption of these models is that among antiretroviral therapy (ART)-naïve individuals, CD4 cell counts decrease over time [30] and the time since infection can be ascertained by applying an estimated rate of CD4 count decline [31].…”