March 31, 2017
Every additional 10% of time spent in HIV care lowered the risk of death about 10% in a 5.5-year study of more than 44,000 people in the United Kingdom. Lower CD4 counts in people with less consistent care partly explained their higher mortality.
Poor retention in HIV care, a persistent problem across the world, can lead to lack of viral suppression, HIV resistance to antiretrovirals and suboptimal CD4-cell gains. Yet, researchers from the University College London and other centers who conducted the UK study note that authorities have not settled on a gold standard to measure retention in HIV care. With a new measure of engagement in care, the UK REACH study determined that HIV patients are in care for 84% of total follow-up time. In this new study, researchers used this measure to assess the impact of engagement in care on mortality in the UK Collaborative HIV Cohort (UK CHIC).
The new analysis involved UK CHIC members at least 16 years old who attended one of 19 clinics between January 2000 and December 2012. UK CHIC records are linked anonymously to mortality data collected by Public Health England. The HIV retention measure uses CD4 counts, viral loads, hemoglobin measures and antiretroviral start/switch dates as markers of clinic attendance.
Researchers put these data into an algorithm to establish the next likely scheduled visit, then counted person-months in and out of care based on whether a patient kept the likely scheduled visit. They used Cox models adjusted for potential confounders to explore associations between mortality and the cumulative proportion of months spent in care (%IC). To reduce the possibility of reverse causality (declining health leading to more clinic visits and thus creating an artificial link between better engagement and higher death risk), the analysis described the relationship between %IC and clinical events one year later.
The study involved 44,432 UK CHIC members, 28% of them women, 53% white and 29% black. Median age at study entry was 36 years and median CD4 count 355 cells/mm3. During a median 5.5 years of follow-up, 6,685 people (15%) acquired a new AIDS diagnosis and 2,279 (5%) died.
Regression analysis adjusted for fixed covariates determined that every 10% higher %IC lowered the risk of death almost 10% (relative hazard [RH] 0.91, 95% confidence interval [CI] 0.88 to 0.95). Further adjustment for use of antiretroviral therapy (ART) did not affect this estimate (RH 0.90, 95% CI 0.87 to 0.93). Adjustment for latest CD4 count attenuated the association (RH 0.96, 95% CI 0.92 to 1.00), a finding indicating that falling CD4 count contributed to the link between missed HIV care visits and death.
The next analysis focused on 8,730 people in follow-up before starting ART. Median %IC stood at 85.7% when ART began. During a median follow-up of 4.3 year, 237 people in this group (2.7%) died. Regression analysis determined that every 10% higher %IC lowered the risk of death almost 70% (RH 0.31, 95% CI 0.18 to 0.51). Further adjustment for (1) baseline antiretroviral regimen and (2) baseline CD4 count and viral load had little impact on this association. But adjustment for latest CD4 count and viral load made the association between %IC and mortality nonsignificant (RH 0.74, 95% CI 0.42 to 1.30).
The researchers conclude that "higher levels of engagement in-care are associated with reduced mortality at all stages of infection, including in those who initiate ART." They believe the study shows that "a combination of routinely collected clinical and laboratory data is able to identify, through engagement patterns, individuals at increased risk of subsequent mortality both before and after starting ART."
Mark Mascolini writes about HIV infection.
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