Point-of-contact interactive record linkage between demographic surveillance and health facilities to measure patterns of HIV service utilisation in Tanzania

As significant investments and efforts have been made to strengthen HIV prevention and care service provisions throughout sub-Saharan Africa, approaches to monitoring uptake of these services have grown in importance. Global HIV/AIDS organisations use routinely updated estimates of the UNAIDS 90-90-90 targets, which state by 2020, 90% of all people living with HIV (PLHIV) should be diagnosed, 90% of diagnosed PLHIV should be receiving treatment, and 90% of PLHIV receiving treatment should achieve viral suppression. Currently, estimates of these targets in sub-Saharan Africa use population based demographic and HIV serological surveillance systems, which comprehensively measure vital events and HIV status but rely on self-reports of health service use. In contrast, most analyses of health service use are limited to patients already diagnosed and enrolled into clinical care and lack a population perspective. This thesis aims to augment existing computer software towards a novel approach to record linkage – termed point-of-contact interactive record linkage (PIRL) – and produce an infrastructure of linked surveillance data and medical records from clinics located within a surveillance area in northwest Tanzania. The linked data are then used to investigate methodological and substantive research questions. Paper A details the PIRL software that was used to collect the data for this thesis. Paper B reviews the data created by PIRL and reports record linkage statistics, including match percentages and attributes associated with (un)successful linkage. A subset of personal identifiers was found to drive the success of the probabilistic linkage algorithm, and PIRL was shown to outperform a fully automated linkage approach. Paper C provides original evidence measuring bias and precision in analyses of linked data with substantial linkage errors. Paper D critiques the estimation of the first 90-90-90 target and shows that current guidelines may underestimate the percentage diagnosed by a relative factor of between 10% and 20%. Finally, Paper E determines that while HIV serological surveillance has increased testing coverage, PLHIV who were diagnosed for HIV in a facility-based clinic were statistically significantly more likely to register for HIV care than those diagnosed at village-level temporary clinics during a surveillance round. Once individuals were in care, there was no evidence of any further delays to treatment initiation by testing modality. The collective findings of this thesis demonstrate the feasibility of PIRL to link community and medical records and use the linked data to measure patterns of HIV service use in a population.