HIV Trends in the United States: Diagnoses and Estimated Incidence.
BACKGROUND
The best indicator of the impact of human immunodeficiency virus (HIV) prevention programs is the incidence of infection; however, HIV is a chronic infection and HIV diagnoses may include infections that occurred years before diagnosis. Alternative methods to estimate incidence use diagnoses, stage of disease, and laboratory assays of infection recency. Using a consistent, accurate method would allow for timely interpretation of HIV trends.


OBJECTIVE
The objective of our study was to assess the recent progress toward reducing HIV infections in the United States overall and among selected population segments with available incidence estimation methods.


METHODS
Data on cases of HIV infection reported to national surveillance for 2008-2013 were used to compare trends in HIV diagnoses, unadjusted and adjusted for reporting delay, and model-based incidence for the US population aged ≥13 years. Incidence was estimated using a biomarker for recency of infection (stratified extrapolation approach) and 2 back-calculation models (CD4 and Bayesian hierarchical models). HIV testing trends were determined from behavioral surveys for persons aged ≥18 years. Analyses were stratified by sex, race or ethnicity (black, Hispanic or Latino, and white), and transmission category (men who have sex with men, MSM).


RESULTS
On average, HIV diagnoses decreased 4.0% per year from 48,309 in 2008 to 39,270 in 2013 (P<.001). Adjusting for reporting delays, diagnoses decreased 3.1% per year (P<.001). The CD4 model estimated an annual decrease in incidence of 4.6% (P<.001) and the Bayesian hierarchical model 2.6% (P<.001); the stratified extrapolation approach estimated a stable incidence. During these years, overall, the percentage of persons who ever had received an HIV test or had had a test within the past year remained stable; among MSM testing increased. For women, all 3 incidence models corroborated the decreasing trend in HIV diagnoses, and HIV diagnoses and 2 incidence models indicated decreases among blacks and whites. The CD4 and Bayesian hierarchical models, but not the stratified extrapolation approach, indicated decreases in incidence among MSM.


CONCLUSIONS
HIV diagnoses and CD4 and Bayesian hierarchical model estimates indicated decreases in HIV incidence overall, among both sexes and all race or ethnicity groups. Further progress depends on effectively reducing HIV incidence among MSM, among whom the majority of new infections occur.
Centers for Disease Control and Prevention, Atlanta, GA, United States.
H Irene
http://orcid.org/0000-0003-0470-8746
HI
Hall
Centers for Disease Control and Prevention, Atlanta, GA, United States.
Ruiguang
http://orcid.org/0000-0002-8025-2595
R
Song
ICF, Atlanta, GA, United States.
Tian
http://orcid.org/0000-0003-4547-9644
T
Tang
Centers for Disease Control and Prevention, Atlanta, GA, United States.
Qian
http://orcid.org/0000-0002-5193-7130
Q
An
Centers for Disease Control and Prevention, Atlanta, GA, United States.
Joseph
http://orcid.org/0000-0002-7336-7634
J
Prejean
Centers for Disease Control and Prevention, Atlanta, GA, United States.
Patricia
http://orcid.org/0000-0002-8861-1484
P
Dietz
Centers for Disease Control and Prevention, Atlanta, GA, United States.
Angela L
http://orcid.org/0000-0002-1334-7084
AL
Hernandez
Centers for Disease Control and Prevention, Atlanta, GA, United States.
Timothy
http://orcid.org/0000-0003-1517-0689
T
Green
Centers for Disease Control and Prevention, Atlanta, GA, United States.
Norma
http://orcid.org/0000-0001-9587-0591
N
Harris
Centers for Disease Control and Prevention, Atlanta, GA, United States.
Eugene
http://orcid.org/0000-0003-3665-0040
E
McCray
Centers for Disease Control and Prevention, Atlanta, GA, United States.
Jonathan
http://orcid.org/0000-0001-9022-4961
J
Mermin
HIV infections; United States; biomarkers; incidence