Using laboratory surveillance data to estimate engagement in care among persons living with HIV in Los Angeles County, 2009.

Poor engagement in HIV care has been associated with delayed access to antiretroviral treatment and increased HIV transmission. Using viral load (VL) results from HIV laboratory surveillance data to conduct longitudinal and cross-sectional analyses, we examined linkage to care, retention in care, and their associated factors in 37,325 persons living with HIV (PLWH) in Los Angeles County (LAC). Linkage to care was considered timely if a VL test result was present ≤3 months of diagnosis. Successful retention in care was defined as having two or more VL test results ≥90 days apart during 2009. Of 6841 persons newly diagnosed with HIV in 2007-2009, 67% were linked to care within 3 months of diagnosis. Factors associated with delayed linkage to care included being African American, Latino, and Asian/Pacific Islander (adjusted hazard ratio [AHR]=0.81; 95% CI=0.75-0.87, AHR=0.83; 95% CI=0.77-0.89, AHR=0.82; 95% CI=0.71-0.94, respectively). Of the 37,325 PLWH, 52% were retained in care during 2009. Factors associated with lack of retention in care included injection drug use (adjusted prevalence ratio [APR]=0.88; 95% CI=0.84-0.93), incarceration at diagnosis (APR=0.56; 95% CI=0.51-0.61), being diagnosed in pre-highly active antiretroviral therapy (HAART) era (APR=0.94; 95% CI=0.92-0.96) or at a public facility (APR=0.97; 95% CI=0.95-1.00), age <45 years (APR=0.87; 95% CI=0.86-0.89), and having concurrent HIV/AIDS diagnoses (APR=0.94; 95% CI=0.92-0.96). This study demonstrates the value of using VL surveillance data to monitor engagement in care among PLWH, and its potential to improve linkage and retention efforts where disparities in care are observed.