This is an open-access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work, first published in JMIR Public Health and Surveillance, is properly cited. The complete bibliographic information, a link to the original publication on http://publichealth.jmir.org, as well as this copyright and license information must be included.
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.
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.
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).
On average, HIV diagnoses decreased 4.0% per year from 48,309 in 2008 to 39,270 in 2013 (
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.
Annual estimates of the number of human immunodeficiency virus (HIV) infections in the United States peaked in the mid-1980s, decreased through the early 1990s, and remained relatively stable through 2010 [
A primary goal of the National HIV/AIDS Strategy for the United States is to reduce HIV incidence [
To assess recent progress toward reducing HIV infections in the United States overall and in selected population segments with available incidence estimation methods, we analyzed data reported to national surveillance programs at the Centers for Disease Control and Prevention (CDC). The data presented include case counts of HIV diagnoses as well as data from new and established models to estimate HIV incidence and testing data from behavioral surveys to aid interpretation of trends. In the United States, large disparities in HIV diagnoses exist among population segments; two-thirds of persons with HIV diagnosed each year are men who have sex with men (MSM), and blacks or African Americans are 8 times and Hispanics or Latinos 3 times as likely to be diagnosed with HIV as white Americans [
Data from the National HIV Surveillance System reported to the CDC through December 2015 were used to determine trends in the annual number of HIV diagnoses in the United States [
Data are presented for 2008 through 2013; starting in 2008, all states and the District of Columbia had implemented name-based HIV reporting and these cases were reported to the National HIV Surveillance System. Diagnoses and incidence estimates were adjusted for missing risk factor information and for determining whether reporting delays may affect the interpretation of trends, we conducted analyses unadjusted and adjusted for reporting delays [
Data on HIV diagnoses and for derived incidence include persons aged 13 years and older at the time of diagnosis or infection, respectively. Trends in these indicators were assessed overall and by sex and race or ethnicity (blacks or African Americans, (hereafter referred to as blacks); Hispanics or Latinos; and whites), and for MSM. HIV surveillance data can be considered to represent a census of HIV diagnoses for the United States and therefore no confidence intervals (CIs) are presented. For estimates of HIV incidence, 95% CIs were calculated. To determine whether there was a significant increasing or decreasing trend in the annual numbers of diagnoses or incidence, the estimated annual percent change (EAPC) in diagnoses and incidence and associated 95% CIs were calculated, and a change in trend was considered statistically significant if
Methods for estimating HIV incidence.
Stratified extrapolation approach [ |
Bayesian hierarchical model [ |
CD4 model [ |
|
Method | Biomarker-based sample survey | Bayesian-based back-calculation | CD4 based back-calculation |
Data requirement | Data for single or multiple years, no limit on number of years | Data for entire epidemic period | Data for recent (8+) years |
All new diagnoses | All new diagnoses | All new diagnoses | |
Incidence assay result on recency of infection | AIDS classification within year of diagnosis | First CD4 after diagnosis | |
Testing and treatment history | |||
Strengths | Annual estimates | Annual estimates | Annual estimates |
More accurate for recent years | Data for entire epidemic period not required | ||
Weaknesses | False recent rate of incidence assay used | HIV data in earlier years incomplete as jurisdictions implemented HIV reporting over time; hence relies on accuracy of data adjustment for incomplete reporting | Relies on accuracy of CD4 depletion model |
Relies on accuracy of testing and treatment information |
Data on HIV testing among the US population are available from the National Health Interview Survey (NHIS) and the Behavioral Risk Factor Surveillance System (BRFSS), and these were used to determine trends in testing (a change in trend was considered statistically significant if
BRFSS is a state-based, random-digit-dialed telephone (landline and mobile) survey of the civilian, noninstitutionalized adult US population that collects information on preventive health practices and risk behaviors. In 2011, BRFSS added mobile phone numbers to the sampling frame and implemented a new weighting methodology. Differences observed in estimates of HIV testing based on 2010 and earlier BRFSS and 2011 and later BRFSS may be attributable to these design changes and estimates of the percentage of persons ever tested during the 2 periods are not comparable [
Data from National HIV Behavioral Surveillance (NHBS) for 2008, 2011, and 2014 were used to determine trends in HIV testing among MSM, ever and within the past 12 months. NHBS monitors HIV-associated behaviors in 20 cities with high AIDS burden [
Annual diagnoses decreased from 48,309 in 2008 to 39,270 in 2013, an average rate of 4.0% per year, and diagnoses adjusted for reporting delays decreased 3.1% per year from 48,938 in 2008 to 41,625 in 2013 (
Percentage of persons reporting testing for HIV, United States, 2008-2014. HIV: human immunodeficiency virus; BRFSS: Behavioral Risk Factor Surveillance System; NHBS: National HIV Behavioral Surveillance; NHIS: National Health Interview Survey; MSM: men who have sex with men.
Number of diagnoses of HIV infection and HIV incidence, by selected characteristics, United States, 2008-2013.
Measure | Year | EAPCa | ||||||||
2008 | 2009 | 2010 | 2011 | 2012 | 2013 | |||||
Diagnoses of HIV infection | No. | 48,309 | 45,688 | 43,637 | 41,793 | 40,872 | 39,270 | −4.0 | <.001 | |
estimated No.b | 48,938 | 46,428 | 44,564 | 43,043 | 42,686 | 41,625 | −3.1 | <.001 | ||
Stratified extrapolation approach | No. | 39,000 | 36,100 | 35,300 | 36,900 | 36,700 | 36,200 | −0.7 | .22 | |
95% CI | 33,600 | 31,100 | 30,500 | 31,800 | 31,600 | 31,200 | ||||
44,400 | 41,000 | 40,200 | 42,000 | 41,800 | 41,300 | |||||
Bayesian hierarchical model | No. | 39,700 | 37,100 | 36,200 | 35,600 | 35,200 | 34,400 | −2.6 | <.001 | |
95% CI | 36,900 | 34,700 | 33,500 | 33,300 | 31,300 | 27,700 | ||||
42,200 | 39,900 | 39,100 | 37,600 | 38,000 | 39,000 | |||||
CD4 model | No. | 46,000 | 43,900 | 41,600 | 40,000 | 38,300 | 36,300 | −4.6 | <.001 | |
95% CI | 44,800 | 42,600 | 40,100 | 38,300 | 36,400 | 34,000 | ||||
47,200 | 45,200 | 43,100 | 41,700 | 40,300 | 38,500 | |||||
Diagnoses of HIV infection | No. | 22,702 | 21,325 | 20,214 | 19,108 | 18,348 | 17,517 | −5.0 | <.001 | |
estimated No.b | 23,013 | 21,695 | 20,669 | 19,722 | 19,234 | 18,666 | −4.1 | <.001 | ||
Stratified extrapolation approach | No. | 17,600 | 15,400 | 14,800 | 16,200 | 15,200 | 15,600 | −1.5 | .09 | |
95% CI | 15,000 | 13,200 | 12,600 | 13,800 | 12,900 | 13,300 | ||||
20,200 | 17,600 | 17,000 | 18,500 | 17,400 | 17,900 | |||||
Bayesian hierarchical model | No. | 18,700 | 16,700 | 15,900 | 16,100 | 16,100 | 15,900 | −3.1 | <.001 | |
95% CI | 16,400 | 14,700 | 14,200 | 14,200 | 14,000 | 11,500 | ||||
21,300 | 18,700 | 17,200 | 17,800 | 19,800 | 21,400 | |||||
CD4 model | No. | 21,600 | 20,700 | 19,300 | 18,300 | 17,000 | 16,100 | −5.7 | <.001 | |
95% CI | 20,700 | 19,700 | 18,200 | 17,100 | 15,700 | 14,500 | ||||
22,400 | 21,600 | 20,300 | 19,500 | 18,300 | 17,600 | |||||
Diagnoses of HIV infection | No. | 9801 | 9466 | 9158 | 8998 | 8997 | 8788 | −2.0 | <.001 | |
estimated No.b | 9928 | 9615 | 9351 | 9263 | 9389 | 9299 | −1.2 | <.001 | ||
Stratified extrapolation approach | No. | 7900 | 7600 | 7600 | 8100 | 8000 | 8100 | 1.0 | .40 | |
95% CI | 6600 | 6300 | 6400 | 6800 | 6700 | 6800 | ||||
9200 | 8800 | 8800 | 9300 | 9200 | 9500 | |||||
Bayesian hierarchical model | No. | 8100 | 8000 | 8100 | 8300 | 8200 | 8100 | 0.4 | .22 | |
95% CI | 7200 | 6500 | 7000 | 7100 | 6100 | 5300 | ||||
8900 | 8900 | 9100 | 9800 | 10,200 | 10,500 | |||||
CD4 model | No. | 9500 | 9200 | 8800 | 8700 | 8700 | 8600 | −2.2 | .05 | |
95% CI | 8900 | 8600 | 8100 | 7800 | 7700 | 7400 | ||||
10,000 | 9900 | 9500 | 9500 | 9700 | 9700 | |||||
Diagnoses of HIV infection | No. | 13,109 | 12,327 | 11,768 | 11,262 | 11,142 | 10,708 | −3.8 | <.001 | |
estimated No.b | 13,264 | 12,506 | 11,993 | 11,559 | 11,574 | 11,275 | −3.1 | <.001 | ||
Stratified extrapolation approach | No. | 11,100 | 10,900 | 10,800 | 10,400 | 11,100 | 10,600 | −0.6 | .63 | |
95% CI | 9300 | 9100 | 9100 | 8700 | 9400 | 8900 | ||||
12,900 | 12,600 | 12,500 | 12,100 | 12,900 | 12,300 | |||||
Bayesian hierarchical model | No. | 11,100 | 10,200 | 10,000 | 10,000 | 10,100 | 9800 | −2.1 | <.001 | |
95% CI | 10,000 | 8300 | 9000 | 8500 | 7800 | 6500 | ||||
12,300 | 11,200 | 10,900 | 12,000 | 12,300 | 12,600 | |||||
CD4 model | No. | 12,400 | 11,500 | 11,100 | 10,700 | 10,400 | 9500 | −4.7 | <.001 | |
95% CI | 11,900 | 10,900 | 10,400 | 9900 | 9500 | 8400 | ||||
13,000 | 12,100 | 11,800 | 11,400 | 11,300 | 10,500 |
aEAPC: estimated annual percent change.
bNumbers are adjusted for reporting delays.
Among blacks, the number of HIV diagnoses decreased 5.0% per year from 2008 to 2013 (4.1% for diagnoses adjusted for reporting delays;
Among males, the number of diagnoses decreased 2.8% per year from 2008 (36,614 diagnoses) to 2013 (31,578 diagnoses; decrease in adjusted diagnoses, 2.0%;
Among men with infection attributed to male-to-male sexual contact, who accounted for 81.3% of males with HIV diagnosed in 2013, the number of HIV diagnoses decreased by 1.0% per year from 2008 (27,119 diagnoses) to 2013 (25,670 diagnoses), with no significant decrease observed in the diagnoses adjusted for reporting delays (
Number of diagnoses of HIV infection and estimated HIV infections, by sex, United States, 2008-2013. HIV: human immunodeficiency virus; BHM: Bayesian hierarchical model; CD4: CD4 model; SEA: stratified extrapolation approach.
Number of diagnoses of HIV infection and estimated HIV infections among MSM, United States, 2008-2013. HIV: human immunodeficiency virus; BHM: Bayesian hierarchical model; CD4: CD4 model; SEA: stratified extrapolation approach; MSM: men who have sex with men.
When analyses were repeated with data adjusted for delays in reporting of HIV diagnoses to the National HIV Surveillance System, the findings varied across models and population segments. For all 3 models, incidence estimates based on data adjusted for reporting delays did not change the interpretation of trends for blacks, whites, and females (data not shown). The Bayesian hierarchical model indicated a small increase in incidence overall (EAPC 0.8%, 95% CI 0.5%-1.1%) and among Hispanics or Latinos (EAPC 3.9%, 95% CI 3.2%-4.5%). For men with infection attributed to male-to-male sexual contact, estimates based on data adjusted for reporting delays from the CD4 (EAPC −1.0%, 95% CI −2.2% to 0.3%) and the Bayesian hierarchical models (EAPC 0.66%, 95% CI 0.31%-1.01%) no longer indicated a decrease in incidence.
The study findings are that diagnoses of HIV infection and incidence estimates from 2 models indicate a reduction in HIV incidence from 2008 through 2013 overall and in subpopulations, including women, men, and MSM. Compared with earlier estimates of the number of new infections in the United States [
Our analyses indicated substantial reductions in HIV incidence in the United States, including among blacks and Hispanics or Latinos, who are disproportionately affected by HIV. The results also suggest modest reductions among MSM, a population with a considerably higher HIV prevalence than heterosexuals, indicating the need for greater reach of HIV prevention services to make substantial reductions in incidence. HIV testing appears to be increasing among MSM, potentially due to large-scale national efforts, with a high and increasing proportion ever tested for HIV and more MSM tested within the past 12 months. This may be reflected in previously reported increases in HIV diagnoses among young MSM who are most likely to have undiagnosed HIV, and the overall increase in awareness of HIV infection among MSM [
More work needs to be done to alleviate the possible reasons that HIV transmission continues at high rates among MSM, including a proportion of MSM with viral suppression well short of national goals [
Blacks and Hispanics or Latinos remain disproportionately affected by HIV compared with whites. In 2013, about 44% of persons who were infected with HIV were black and about 24% Hispanic or Latino, compared with them comprising 12% and 17% of the US population, respectively. The decreasing trends in diagnoses and incidence among women are encouraging and, as previously reported, are mirrored by decreasing diagnoses among black, Hispanic or Latino, and white women [
There are some limitations to each of the measures available to estimate trends in HIV incidence. Diagnoses represent a census of events for the United States. However, trends in diagnoses depend on testing rates and are subject to diagnosis delays, with an estimated median delay between HIV infection and HIV diagnosis of 3.6 years (mean 5.6 years) for 2011 [
In summary, incidence models estimated that about 36,000 people were infected with HIV in the United States in 2013. From 2008 to 2013, HIV diagnoses decreased overall, among both sexes and all race or ethnicity groups, and similar to earlier estimates of HIV incidence [
antiretroviral treatment
Behavioral Risk Factor Surveillance System
estimated annual percent change
human immunodeficiency virus
men who have sex with men
National Health Interview Survey
National HIV Behavioral Surveillance
The findings and conclusions in this study are those of the authors and do not necessarily represent the views of the CDC.
None declared.