Lower CD4+ counts at HIV diagnosis have been attributed to infrequent testing and subsequently delayed care, conferring higher risk of transmission, opportunistic infection, and mortality. The actual interval of seroconversion has been difficult to characterize in the general population other than in cases of acute HIV. Using data from a military cohort subject to mandated screening, we evaluated the association between HIV testing intervals and CD4+ at diagnosis of HIV.
We retrospectively evaluated participants in the US Military HIV Natural History Study from 2000-2014 who seroconverted during military service. Descriptive statistics were performed for demographic data. Means and IQRs were obtained for initial CD4+ count at HIV diagnosis by year. LOESS curves were plotted for CD4+ by testing interval, as well as testing interval and CD4+ each by calendar year. Multivariable regression assessed the effect of testing interval on CD4+ at HIV diagnosis, controlling for calendar year, gender, race, age, and viral load.
1258 participants met inclusion criteria, with 76.6% having a diagnostic interval <2 years from date of last negative test and 40.3% <1 year. Overall, HIV testing interval was associated with decreasing CD4+ at HIV diagnosis (p<0.001). Mean initial CD4+ was 466 cells/uL (IQR 343-605), with an adjusted difference in CD4+ of -35 cells/uL [95% CI -60, -10] for testing intervals of 1-2 years and -64 cells/uL [95% CI -93, -34] for ≥2 years as compared to testing intervals <1 year. These associations remained significant in multivariable analyses when controlling for calendar year. Additionally, patients with diagnostic intervals >2 years had twice the rate of AIDS by CD4+ criteria than those with earlier diagnoses (9% v. 4% and 5%, p=0.027). Associations were observed with nonwhite race, but not initial viral load or calendar year.
Longer intervals between HIV screening tests are associated with small but important differences in initial CD4+ in a military cohort. A screening interval of greater than two years is associated with double the rate of AIDS by CD4+ criteria at the time of HIV diagnosis when compared with more frequent testing in US military personnel.
B. Agan, None
J. Okulicz, None
T. Lalani, None
R. Deiss, None
M. Bavaro, None
R. Maves, None