One Pill, Once a Day: Simplified Treatment Regimens and Retention in HIV Care

Abstract

Simplified drug regimens may improve retention in care for persons with chronic diseases. In April 2013, South Africa adopted a once-daily single-pill human immunodeficiency virus (HIV) treatment regimen as the standard of care, replacing a multiple-pill regimen. Because the regimens had similar biological efficacy, the shift to single-pill therapy offered a real-world test of the impact of simplified drug-delivery mechanisms on patient behavior. Using a quasi-experimental regression discontinuity design, we assessed retention in care among patients starting HIV treatment just before and just after the guideline change. The study included 4,484 patients starting treatment at a large public sector clinic in Johannesburg, South Africa. The share of patients prescribed a single-pill regimen increased by over 40 percentage points between March and April 2013. Initiating treatment after the policy change was associated with 11.7-percentage-points' higher retention at 12 months (95% confidence interval: -2.2, 29.4). Findings were robust to different measures of retention, different bandwidths, and different statistical models. Patients starting treatment early in HIV infection-a key population in the test-and-treat era-experienced the greatest improvements in retention from single-pill regimens.

Keywords: HIV; South Africa; fixed-dose combination treatment; instrumental variables; regression discontinuity; retention in care; single-tablet treatment.

Figure 1

Monthly proportion of all patients initiating standard first-line antiretroviral therapy at Themba Lethu Clinic who were prescribed a single-pill regimen, Johannesburg, South Africa, 2011–2014. Dots represent monthly percentages; lines represent local linear regression models with a 70-day bandwidth and a triangular kernel. FDC, fixed-dose combination.

Figure 2

Proportion of patients with a 4-month gap in care among patients starting antiretroviral therapy before and after the switch to a single-pill regimen, Themba Lethu Clinic, Johannesburg, South Africa, 2011–2014. Dots represent monthly percentages; lines represent local linear regression models with a bandwidth of 147.0 days and a triangular kernel.

Figure 3

Secondary attrition outcomes among patients who initiated antiretroviral therapy at Themba Lethu Clinic in Johannesburg, South Africa, 2011–2014. A) Absence from care at 1 year; B) long-term attrition by 1 year; C) failure to have a 6-month viral load measurement. Dots represent monthly percentages; lines represent local linear regression models with bandwidths of 143.5 days (A), 146.3 days (B), and 193.3 days (C) and a triangular kernel.