Trends in CD4 and viral load testing 2005 to 2018: multi-cohort study of people living with HIV in Southern Africa

Abstract

Introduction: The World Health Organization (WHO) recommends a CD4 cell count before starting antiretroviral therapy (ART) to detect advanced HIV disease, and routine viral load (VL) testing following ART initiation to detect treatment failure. Donor support for CD4 testing has declined to prioritize access to VL monitoring. We examined trends in CD4 and VL testing among adults (≥15 years of age) starting ART in Southern Africa.

Methods: We analysed data from 14 HIV treatment programmes in Lesotho, Malawi, Mozambique, South Africa, Zambia and Zimbabwe in 2005 to 2018. We examined the frequency of CD4 and VL testing, the percentage of adults with CD4 or VL tests, and among those having a test, the percentage starting ART with advanced HIV disease (CD4 count <200 cells/mm³ ) or failing to suppress viral replication (>1000 HIV-RNA copies/mL) after ART initiation. We used mixed effect logistic regression to assess time trends adjusted for age and sex.

Results: Among 502,456 adults, the percentage with CD4 testing at ART initiation decreased from a high of 78.1% in 2008 to a low of 38.0% in 2017; the probability declined by 14% each year (odds ratio (OR) 0.86; 95% CI 0.86 to 0.86). Frequency of CD4 testing also declined. The percentage starting ART with advanced HIV disease declined from 83.3% in 2005 to 23.5% in 2018; each year the probability declined by 20% (OR 0.80; 95% CI 0.80 to 0.81). VL testing after starting ART varied; 61.0% of adults in South Africa and 10.7% in Malawi were tested, but fewer than 2% were tested in the other four countries. The probability of VL testing after ART start increased only modestly each year (OR 1.06; 95% CI 1.05 to 1.06). The percentage with unsuppressed VL was 8.6%. There was no evidence of a decrease in unsuppressed VL over time (OR 1.00; 95% CI 0.99 to 1.01).

Conclusions: CD4 cell counting declined over time, including testing at the start of ART, despite the fact that many patients still initiated ART with advanced HIV disease. Without CD4 testing and expanded VL testing many patients with advanced HIV disease and treatment failure may go undetected, threatening the effectiveness of ART in sub-Saharan Africa.

Keywords: Africa; CD4 lymphocyte count; Cohort studies; HIV infections; Southern; antiretroviral therapy; highly active; viral load.

Figure 1

Frequency of CD4 cell count testing per day and cumulative number of adult patients in care by country. The vertical lines indicate the change in WHO guidelines. Scale of y‐axis differs across countries.

Figure 2

Frequency of viral load testing per day and cumulative number of adult patients in care by country. The vertical lines indicate the change in WHO guidelines. Scale of y‐axis differs across countries.

Figure 3

Trend of the ratio of CD4 cell count testing to viral load testing among adult patients by year of testing. The vertical lines indicate the change in WHO guidelines.

Figure 4

Trends of CD4 cell count testing at antiretroviral therapy (ART) start and viral load (VL) testing after ART start among adult patients by year of ART start. (a) The percentage of patients with a CD4 cell count at antiretroviral therapy (ART) start and, among those, (c) the percentage with advanced HIV disease; and (b) the percentage with a VL test three to nine months after ART start and, among those, (d) the percentage with unsuppressed VL by year of ART start. Advanced HIV disease defined as CD4 cell count <200 cells/mm³; unsuppressed VL defined as HIV‐1 RNA > 1000 copies/mL. The vertical lines indicate the change in WHO guidelines.