Retention in care and connection to care among HIV-infected patients on antiretroviral therapy in Africa: estimation via a sampling-based approach

Abstract

Introduction: Current estimates of retention among HIV-infected patients on antiretroviral therapy (ART) in Africa consider patients who are lost to follow-up (LTF) as well as those who die shortly after their last clinic visit to be no longer in care and to represent limitations in access to care. Yet many lost patients may have "silently" transferred and deaths shortly after the last clinic visit more likely represent limitations in clinical care rather than access to care after initial linkage.

Methods: We evaluated HIV-infected adults initiating ART from 1/1/2004 to 9/30/2007 at a clinic in rural Uganda. A representative sample of lost patients was tracked in the community to obtain updated information about care at other ART sites. Updated outcomes were incorporated with probability weights to obtain "corrected" estimates of retention for the entire clinic population. We used the competing risks approach to estimate "connection to care"--the percentage of patients accessing care over time (including those who died while in care).

Results: Among 3,628 patients, 829 became lost, 128 were tracked and in 111, updated information was obtained. Of 111, 79 (71%) were alive and 35/48 (73%) of patients interviewed in person were in care and on ART. Patient retention for the clinic population assuming lost patients were not in care was 82.3%, 68.9%, and 60.1% at 1, 2 and 3 years. Incorporating updated care information from the sample of lost patients increased estimates of patient retention to 85.8% to 90.9%, 78.9% to 86.2% and 75.8% to 84.7% at the same time points.

Conclusions: Accounting for "silent transfers" and early deaths increased estimates of patient retention and connection to care substantially. Deaths soon after the last clinic visit (potentially reflecting limitations in clinical effectiveness) and disconnection from care among patient who were alive each accounted for approximately half of failures of retention.

Figure 1. Naïve and corrected plots of “retention in care.”

Retention in care is defined as the fraction of patients who remain alive and in HIV care. The naïve estimate assumes that all patients who are lost to follow-up from the ISS clinic are no longer retained in care. The corrected estimates of retention in care are based on outcomes ascertained from a sample of patients who were lost to follow-up from the ISS Clinic, sought in the community and in whom updated information about vital status and HIV care was obtained. If a tracked patient was found to be alive by report of an informant, we did not ask that informant whether the patient was still in HIV care because this could inadvertently violate the privacy of the patient. Therefore, we conducted a sensitivity analysis under two assumptions. The “pessimistic” corrected estimate is based on the assumption that all patients who were alive but not directly interviewed in person were no longer in HIV care. The “optimistic” corrected estimate was based on the assumption that all patients who were reported to be alive but not directly interviewed in person remained in HIV care.

Figure 2. Naïve and corrected estimates of “connection to care.”

Connection to care uses a competing risk approach to estimate the probability of ART initiators access care and includes patients who are alive and continuing to use the clinic as well as those died while accessing care (i.e., who died shortly after their last clinic visit).