Prevalence and Correlates of Unknown HIV Infection among Patients Seeking Care in a Public Hospital Emergency Department

Although the Centers for Disease Control and Prevention (CDC) recommend routine HIV counseling, testing, and referral (HIVCTR) in settings with at least a 1 percent prevalence of HIV, roughly 280,000 Americans are unaware of their human immunodeficiency virus (HIV) infection. The effect of expanded screening for HIV is unknown in the era of effective antiretroviral therapy. We developed a computer simulation model of HIV screening and treatment to compare routine, voluntary HIVCTR with current practice in three target populations: "high-risk" (3.0 percent prevalence of undiagnosed HIV infection; 1.2 percent annual incidence); "CDC threshold" (1.0 percent and 0.12 percent, respectively); and "U.S. general" (0.1 percent and 0.01 percent). Input data were derived from clinical trials and observational cohorts. Outcomes included quality-adjusted survival, cost, and cost-effectiveness. In the high-risk population, the addition of one-time screening for HIV antibodies with an enzyme-linked immunosorbent assay (ELISA) to current practice was associated with earlier diagnosis of HIV (mean CD4 cell count at diagnosis, 210 vs. 154 per cubic millimeter). One-time screening also improved average survival time among HIV-infected patients (quality-adjusted survival, 220.7 months vs. 219.8 months). The incremental cost-effectiveness was 36,000 dollars per quality-adjusted life-year gained. Testing every five years cost 50,000 dollars per quality-adjusted life-year gained, and testing every three years cost 63,000 dollars per quality-adjusted life-year gained. In the CDC threshold population, the cost-effectiveness ratio for one-time screening with ELISA was 38,000 dollars per quality-adjusted life-year gained, whereas testing every five years cost 71,000 dollars per quality-adjusted life-year gained, and testing every three years cost 85,000 dollars per quality-adjusted life-year gained. In the U.S. general population, one-time screening cost 113,000 dollars per quality-adjusted life-year gained. In all but the lowest-risk populations, routine, voluntary screening for HIV once every three to five years is justified on both clinical and cost-effectiveness grounds. One-time screening in the general population may also be cost-effective. Copyright 2005 Massachusetts Medical Society.

Differentiating individuals with early human immunodeficiency virus 1 (HIV-1) infection from those infected for longer periods is difficult but important for estimating HIV incidence and for purposes of clinical care and prevention. To develop and validate a serologic testing algorithm in which HIV-1-positive persons with reactive test results on a sensitive HIV-1 enzyme immunoassay (EIA) but nonreactive results on a less sensitive (LS) EIA are identified as having early infection. Diagnostic test and testing strategy development, validation, and application. Specimens were tested with both a sensitive HIV-1 EIA (3A11 assay) and a less sensitive modification of the same EIA (3A11-LS assay). For assay development: 104 persons seroconverting to HIV-1 comprising 38 plasma donors, 18 patients of a sexually transmitted disease clinic in Trinidad, and 48 participants in the San Francisco Men's Health Study (SFMHS); 268 men without the acquired immunodeficiency syndrome (AIDS) in the SFMHS who had been infected for at least 2.5 years; and 207 persons with clinical AIDS; for testing strategy validation: 488 men in the SFMHS from 1985 through 1990 and 1275449 repeat blood donors at 3 American Red Cross blood centers from 1993 through 1995; and for HIV-1 incidence estimates: 2717910 first-time blood donors. We retrospectively identified persons eligible for a study of early infection. Ability to identify early HIV infection. Estimated mean time from being 3A11 reactive/3A11-LS nonreactive to being 3A11 reactive/3A11-LS reactive was 129 days (95% confidence interval [CI], 109-149 days) [corrected]. Our testing strategy accurately diagnosed 95% of persons with early infection; however, 0.4% (1/268) of men with established infection and 2% (5/207) of persons with late-stage AIDS were misdiagnosed as having early HIV-1 infection. Average yearly incidence estimates in SFMHS subjects were 1.5% per year vs observed average incidence of 1.4 per 100 person-years. Incidence in repeat blood donors using the sensitive/less sensitive assay testing strategy was 2.95 per 100000 per year (95% CI, 1.14-6.53/100000) vs observed incidence of 2.60 per 100000 person-years (95% CI, 1.49-4.21/100000). Overall incidence in first-time blood donors was 7.18 per 100000 per year (95% CI, 4.51-11.20/100000) and did not change statistically significantly between 1993 and 1996. Use of the sensitive/less sensitive testing strategy alone would have identified all 17 persons with antibodies to HIV-1 eligible for a study of early HIV-1 infection and would have increased enrollment. The sensitive/less sensitive testing strategy provides accurate diagnosis of early HIV-1 infection, provides accurate estimates of HIV-1 incidence, can facilitate clinical studies of early HIV-1 infection, and provides information on HIV-1 infection duration for care planning.

We determined proportions of high-risk persons tested for HIV, the reasons for testing and not testing, and attitudes and perceptions regarding HIV testing, information that is critical for planning prevention programs. Cross-sectional interview study of persons at high risk for HIV infection (men who have sex with men [MSM]; injection drug users [IDUs]; and heterosexual persons recruited from gay bars, street outreach, and sexually transmitted disease clinics) among six states participating in the HIV Testing Survey (HITS) in 1995 to 1996 (HITS-I) and 1998 to 1999 (HITS-II). Overall testing rates were lower in the HITS-I (1226/1599 [77%]) than in the HITS-II (1375/1711 [80%]) (p =.01). Persons or=25 years old (HITS-I: 71% vs. 78%, respectively, p=.007; HITS-II: 63% vs. 85%, respectively, p<.001). The main reasons for testing and not testing were the same in both surveys, but the proportions of reasons for not testing differed (e.g., "unlikely exposed to HIV" [HITS-I (17%) vs. HITS-II (30%), p<.0001], "afraid of finding out HIV-positive" [HITS-I (27%) vs. HITS-II (18%), p<.0001]). Attitudes regarding HIV testing differed among tested and untested respondents, especially among MSM. HIV testing rates were higher in the HITS-II, but testing rates decreased among the youngest respondents. Denial of HIV risk factors and fear of being HIV-positive were the principal reasons for not being tested. Availability of new HIV therapies may have contributed to decreased fear of finding out that one is HIV infected as a reason to avoid testing. The increased proportion of persons at risk who did not test because they believed they were unlikely to have been exposed highlights the need for prevention efforts to address risk perceptions.