Impact of migration on calculated prevalence and incidence of HIV in a longitudinal population-based cohort in rural Uganda

Dermot Maher, MRC/UVRI Uganda Research Unit on AIDS

Introduction: Longitudinal population-based cohort studies of HIV are important for quantifying HIV burden and understanding HIV population dynamics. We examine the impact of migration in calculating HIV prevalence and incidence in a rural Ugandan cohort. Methods: Data on participants’ HIV and residence status from an annual survey of a cohort since 1989 are used to to assess how migration affects the numerator and denominator in HIV prevalence and incidence calculations. Results: The proportion of seropositive in-migrants among HIV seropositive cases varied between about 10%-20% over the past two decades. Mobility (in- and out-migration) is greatest among people aged 15-30 years, in whom out-migration exceeds in-migration, and is more common among females than males. Results will be presented on the overall impact of migration on HIV prevalence and incidence calculations. Conclusion: Quantifying the impact of in- and out-migration enables the avoidance of possible systematic bias in HIV prevalence and incidence calculations.