Quantifying clinic transfers among people living with HIV in the Western Cape, South Africa: a retrospective spatial analysis

Abstract

Objectives: For persons living with HIV (PLWH) in long-term care, clinic transfers are common and influence sustained engagement in HIV care, as they are associated with significant time out-of-care, low CD4 count, and unsuppressed viral load on re-entry. Despite the geospatial nature of clinic transfers, there exist limited data on the geospatial trends of clinic transfers to guide intervention development. In this study, we investigate the geospatial characteristics and trends of clinic transfers among PLWH on antiretroviral therapy (ART) in the Western Cape Province of South Africa.

Design: Retrospective spatial analysis.

Setting: PLWH who initiated ART treatment between 2012 and 2016 in South Africa's Western Cape Province were followed from ART initiation to their last visit prior to 2017. Deidentified electronic medical records from all public clinical, pharmacy, and laboratory visits in the Western Cape were linked across space and time using a unique patient identifier number.

Participants: 4176 ART initiators in South Africa (68% women).

Methods: We defined a clinic transfer as any switch between health facilities that occurred on different days and measured the distance between facilities using geodesic distance. We constructed network flow maps to evaluate geospatial trends in clinic transfers over time, both for individuals' first transfer and overall.

Results: Two-thirds of ART initiators transferred health facilities at least once during follow-up. Median distance between all clinic transfer origins and destinations among participants was 8.6 km. Participant transfers were heavily clustered around Cape Town. There was a positive association between time on ART and clinic transfer distance, both among participants' first transfers and overall.

Conclusion: This study is among the first to examine geospatial trends in clinic transfers over time among PLWH. Our results make clear that clinic transfers are common and can cluster in urban areas, necessitating better integrated health information systems and HIV care.

Keywords: epidemiology; hiv & aids.

Figure 1

Network flow map of participants’ first clinic transfer during ART treatment. Panel (A) contextualises the Western Cape Province (outlined in red) within South Africa. Panel (B) (the Western Cape outlined in red) depicts the first clinic transfer of each of the 2797 individuals who transferred at least once following ART initiation. A black line represents at least one transfer between facility endpoints. Direction of transfer is not specified. Panel (C) zooms into the City of Cape Town metropolitan municipality outlined in blue. Out of 2797 first transfers, 2694 (96%) occurred within the Cape Town municipality. Panel (D) further zooms into the Klipfontein health subdistrict (outlined in purple) where all participants first tested positive for HIV in 2012 or 2013. A green line depicts a transfer whose origin facility was within Klipfontein (1823 out of 2797 transfers, or 65%). The black dots mark specific hubs of participant movement originating from within Klipfontein. Panel (E) removes the traffic across the Klipfontein boundary, depicting only those 567 first clinic transfers (20%) that occurred strictly within Klipfontein (outlined in purple).