Implementation and Operational Research: Engagement in HIV Care Among Persons Enrolled in a Clinical HIV Cohort in Ontario, Canada, 2001-2011.

Ensuring that people living with HIV are accessing and staying in care is vital to achieving optimal health outcomes including antiretroviral therapy (ART) adherence and prevention of secondary transmission.1–4 A number of jurisdictions are quantifying patterns of care engagement among persons diagnosed with HIV with an eye to identifying potential barriers against the full realization of these individual and population benefits.5–9 The continuum of care engagement or “HIV care cascade” is a framework that depicts the degree to which people infected with HIV are diagnosed in a timely fashion, become engaged in HIV care, and are successfully treated with ART such that they achieve virologic suppression.5 Findings in 1 setting may not be generalizable to another, given differences in health care systems and populations affected by local HIV epidemics. International comparisons indicate variation in the percent loss from 1 cascade step to the next that may vary considerably,10 suggesting that locally informed strategies may be required to improve retention and ultimately the proportion with suppressed viral load. Estimation of HIV care engagement indicators commonly uses administrative health data from clinics, laboratory systems, or health insurance programs.5,8,9,11–13 Although such data sources typically benefit from being population-based, they may lack patient-level characteristics (eg, HIV risk factors, race/ethnicity, immigration status) or, for those measures that are collected, may have extensive missing data. Data from consented participants in ongoing cohort studies typically have far better ascertainment of such characteristics but may be prone to selection biases because of differential enrollment and attrition. Ideally, one would triangulate using both types of data sources for robust inferences. Our overall objective was to characterize HIV care engagement among participants of a large clinical cohort in Ontario, Canada, that conducts record linkage with population-based administrative health databases. All cohort participants have been diagnosed with HIV and were successfully linked to HIV care; nevertheless, this population can inform patterns of subsequent HIV care engagement after linkage to care. Specifically, we sought to estimate the annual proportions in care, in continuous care, on ART, and with suppressed viral load from 2001 to 2011 and to examine whether patterns in these outcomes varied temporally or according to socio-demographic characteristics.