Using serial cross-sectional surveys to create a retrospective nested cohort to determine HIV incidence from 20 US...

To estimate HIV incidence using successive cross-sectional surveys by creating retrospective nested cohorts among MSM, people who inject drugs (PWID), and heterosexually active persons (HET).

Cohorts were created among participants who had at least one repeat observation across four surveillance cycles from National HIV Behavioral Surveillance in 20 US cities.

Repeat participants were identified using a combination of date of birth, race/ethnicity, metropolitan statistical area, and gender. The analysis was limited to participants who tested negative for HIV at baseline and were assumed to be at risk between cycles. We calculated person-years at risk from the individual time between cycles and used the total number of seroconversions to estimate incidence and a Poisson distribution to approximate variance. Rate ratios were calculated using age, gender, race/ethnicity, and region.

From 2008 to 2019, successive surveys recaptured nested cohorts of 1747 MSM, 3708 PWID, and 1396 HET. We observed an incidence rate of 2.5 per 100 person-years [95% confidence interval (CI) 2.1-2.8) among MSM; 0.6 per 100 person-years (95% CI 0.5-0.7) among PWID; and 0.3 per 100 person-years (95% CI 0.1-0.4) among HET. HIV incidence was higher among younger MSM, black MSM (compared with white MSM), and PWID residing in the South and territories (compared with the Midwest).

These estimates are consistent with previously published incidence estimates from prospective cohort studies among these populations. Using repeat cross-sectional surveys to simulate a cohort, may serve as another strategy in estimating HIV incidence.