"Linkage to care" among people living with HIV - definition in the era of "universal test and treat" in a sub-Sahara African setting

BACKGROUND: Prompt linkage to human immunodeficiency virus (HIV) care after diagnosis is of utmost importance for individual health and reduction of HIV transmission. Different definitions for "linkage to care" have challenged comparisons as a public health marker. Its meaning in the era of "universal test and treat" has transformed in all settings, but is most relevant in sub-Sahara Africa, where the burden of new HIV infection is still highest. METHODS: For this narrative review on "linkage to care" definitions with a focus on sub-Saharan Africa, we searched PubMed/Medline between September and December 2020, restricted to the period 2000-2020 using Boolean operators: "HIV" AND ("linkage to care" OR "engagement in care") and screened for institutional definitions of "linkage to care". Additionally, as one example of a rural sub-Saharan African setting, we analysed linkage steps within the Chronic Diseases Clinic Ifakara (CDCI) and its associated Kilombero and Ulanga Antiretroviral Cohort (KIULARCO) in rural Tanzania between 1 January 2017 and 31 March 2019. RESULTS: We analysed 81 articles that included "linkage to care" within different study settings and HIV organisations. Major differences in defining "linkage to care" exist, according to setting and location, patient populations and the timing of steps within the linkage process. We identified 16 different numerators and 10 denominators used to define linkage with time periods ranging from "same day as diagnosis" up to 12 months after diagnosis among 34 original articles from sub-Saharan Africa. At the CDCI, 1149/1671 (69%) newly diagnosed individuals were enrolled into care after diagnosis. Three months after enrolment into care, 94%, 86%, 85% and 71% of enrolled patients had a laboratory evaluation, a clinical evaluation, were initiated on treatment and had a first clinical follow-up visit after initiation of treatment, respectively. DUSCUSSION: To address the inconsistency in defining "linkage to care" and in order to guarantee the comparability of "linkage to care" in the sub-Saharan Africa region, we support the definition from the European region with some adaptions. We suggest a priority list of care indicators if more than one care indicator is available for successful "linkage to care" in the era of "universal test and treat" for sub-Sahara Africa.