Estimated HIV Incidence in California, 2006-2009.

INTRODUCTION: Accurate estimates of HIV incidence are crucial for prioritizing, targeting, and evaluating HIV prevention efforts. Using the methodology the CDC used to estimate national HIV incidence, we estimated HIV incidence in Los Angeles County (LAC), San Francisco (SF), and California's remaining counties. METHODS: We estimated new HIV infections in 2006-2009 among adults and adolescents in LAC, SF and the remaining California counties using the Serologic Testing Algorithm for Recent Seroconversion (STARHS). STARHS methodology uses the BED HIV-1 capture enzyme immunoassay to determine recent HIV infections by testing remnant serum from persons newly diagnosed with HIV. A population-based incidence estimate is calculated using HIV testing data from newly diagnosed cases and imputing for persons unaware of their HIV infection. RESULTS: For years 2007-2009, respectively, we estimated new infections in LAC to be 2426 (95% CI 1871-2982), 1669 (CI 1309-2029) and 1898 (CI 1452-2344) (p<0.01); in SF for 2006-2009, 492 (CI 327-657), 490 (CI 335-646), 458 (CI 342-574) and 367 (CI 261-473) (p = 0.14); and in the remaining California counties in 2008-2009, 2526 (CI 1688-3364) and 2993 (CI 2141-3846) respectively. HIV infection rates among men who have sex with men (MSM) in LAC were 100 times higher than other risk populations; the SF MSM rate was 3 to 18 times higher than other demographic groups. In LAC, incidence rates among African-Americans were twice those of whites and Latinos; persons 40 years or older had lower rates of infection than younger persons. DISCUSSION: We report the first HIV incidence estimates for California, highlighting geographic disparities in HIV incidence and confirming national findings that MSM and African-Americans are disproportionately impacted by HIV. HIV incidence estimates can and should be used to target prevention efforts towards populations at highest risk of acquiring new HIV infections, focusing on geographic, racial and risk group disparities.

Do people who develop AIDS within 12 months of HIV diagnosis delay HIV testing?

OBJECTIVE: Individuals diagnosed with AIDS within 12 months of HIV diagnosis have been considered "late testers." Prevalence estimates of late testers have been made using HIV/AIDS surveillance data, and high rates of late testing have been reported. However, studies evaluating this definition have not been conducted. We measured the degree of misclassification of delayed testing based on this surveillance definition of late testing. METHODS: We used dates of negative HIV tests among people who met this definition of late testing in San Francisco from 2007 to 2008 to reclassify people as "verified non-late testers" if there was a negative HIV test within five years of HIV diagnosis, as "verified late testers" if there were no prior tests or if negative tests were recorded five or more years prior to diagnosis, or as "late-tester status not verified." We measured misclassification of late-tester status and the prevalence of late testing using the different definitions of late testing. RESULTS: Of the 270 people who developed AIDS within 12 months of HIV diagnosis, we found that 89 (33.0%) were verified late testers, 131 (48.5%) were verified non-late testers, and 50 (18.5%) were unverifiable. Using the surveillance definition (individuals who develop AIDS within 12 months of HIV diagnosis), the prevalence of late testing was 26.3%, whereas it was 9.0% when restricted to individuals verified as late testers. CONCLUSION: Defining people who develop AIDS within 12 months of HIV diagnosis without taking into consideration the dates of prior negative HIV tests leads to substantial misclassification of late testing.

Identifying barriers to HIV testing: personal and contextual factors associated with late HIV testing.

Late diagnosis of HIV is associated with increased morbidity, mortality, and health care costs. Despite the availability of HIV testing, persons continue to test late in the course of HIV infection. We used the HIV/AIDS case registry of San Francisco Department of Public Health to identify and recruit 41 persons who developed AIDS within 12 months of their HIV diagnosis to participate in a qualitative and quantitative interview regarding late diagnosis of HIV. Thirty-one of the participants were diagnosed with HIV because of symptomatic disease and 50% of the participants were diagnosed with HIV and AIDS concurrently. Half of the subjects had not been tested for HIV prior to diagnosis. Fear was the most frequently cited barrier to testing. Other barriers included being unaware of improved HIV treatment, free/low cost care, and risk for HIV. Recommendations for health care providers to increase early diagnosis of HIV include routine ascertainment of HIV risk behaviors and testing histories, stronger recommendations for patients to be tested, and incorporating testing into routine medical care. Public health messages to increase testing include publicizing that (1) effective, tolerable, and low cost/free care for HIV is readily available, (2) early diagnosis of HIV improves health outcomes, (3) HIV can be transmitted to persons who engage in unprotected oral and insertive anal sex and unprotected receptive anal intercourse without ejaculation and from HIV-infected persons whose infection is well-controlled with antiretroviral therapy, (4) persons who may be infected based upon these behaviors should be tested following exposure, (5) HIV testing information will be kept private, and (6) encouraging friends and family to get HIV tested is beneficial.

Estimation of HIV incidence in San Francisco.

The Centers for Disease Control and Prevention recently released the first direct national estimate of HIV incidence. Local jurisdictions have begun to apply this methodology. The national and local estimates have been higher than assumed. When applied to San Francisco, there were 935 new HIV infections [95% confidence interval (CI) 658-1212] during 2006. We compared this incidence estimate to an estimate produced in San Francisco in 2006 by a panel of HIV researchers using an iterative Delphi method. Results were similar. Further corroboration of the new method in local areas would strengthen interpretation and identify HIV risk variations.