About half of U.S. adults have had an HIV test, but testing often occurs late in the course of infection.

Nearly half of Americans aged 18 or older have ever been tested for HIV, and nearly two-thirds of those were tested voluntarily, primarily to learn their infection status, according to a 2001 Centers for Disease Control and Prevention (CDC) survey. (1) In nine states, women were more likely than men to have ever been tested, and in all but three states, they were more likely than men to have been tested voluntarily. In another study conducted by the CDC, people tested late in the course of HIV disease were more likely than those tested early to be young, black or Hispanic; to have acquired HIV through heterosexual contact; and to have had a high school education or less. (2) Findings from these two studies provide an important backdrop to the CDC's new emphasis on increased and early HIV/testing.

HIV Testing in the United States 

To determine the proportion of Americans who have ever been tested for HIV and the proportion who were tested voluntarily, the CDC analyzed data from the 2001 Behavioral Risk Factor Surveillance System--a telephone survey of people aged 18 or older in the 50 states, the District of Columbia, Guam, Puerto Rico and the U.S. Virgin Islands. In addition to questions about HIV and AIDS knowledge and attitudes, participants were asked "As far as you know, have you ever had your blood tested for HIV?" Those who reported ever having been tested were also asked "What was the main reason you had your test for HIV?" Respondents who answered "just to find out if infected," "routine check-up," "doctor referral," "sex partner referral," "because of pregnancy," "because I am at risk" or "other" were considered to have been tested voluntarily; those who were tested because of illness, hospitalization or surgery, or for insurance, employment, a marriage license, military service, immigration or occupational exposure were considered to have been tested involuntarily. Data were weighted by demographic characteristics.

Overall, 170,412 survey participants aged 18-64 answered questions regarding HIV and AIDS. A median of 46% had ever been tested for HIV; respondents in South Dakota had the lowest testing rate (32%), and those in the District of Columbia had the highest (65%). The median age of those who had ever been tested was 35.1. Of respondents who had been tested, a median of 28% had done so in the year before the survey, Maine had the lowest recent testing rate (19%), and the Virgin Islands had the highest (40%).

Of respondents who had ever been tested for HIV, a median of 64% had been tested voluntarily; the highest rate of voluntary testing was found in the District of Columbia (80%), and the lowest in South Dakota (53%). Overall, comparable proportions of men and women had been tested for HIV (44% and 48%, respectively) and had been tested in the last 12 months (29% and 27%). However, women were significantly more likely than men to have been tested in nine states--California, Kentucky, Louisiana, Minnesota, Mississippi, Montana Tennessee, Texas and Washington--and in Puerto Rico, and to have been tested in the last year in Hawaii. Among those who had ever been tested, 55% of men and 72% of women reported having been tested voluntarily; women were more likely than men to have been tested voluntarily in 47 states, Guam, Puerto Rico and the Virgin Islands.

The researchers comment that the geographic variations in HIV testing may be caused by "area-specific differences in the prevalence of HIV infection and AIDS" and in the scope of interventions, whereas the gender variations are likely a result of testing during pregnancy. They add that gender differences may be an important consideration in the development of HIV prevention and education programs.

Early vs. Late Testing

In the other study, researchers interviewed people aged 18 or older with HIV or AIDS between May 2000 and February 2003 at 16 sites in different states. Using the date on which AIDS was diagnosed as supplied by state or local reporting systems, they defined participants as early testers (those who had had their first positive HIV test five or more years before the diagnosis of AIDS, or had gone five or more years without a diagnosis of AIDS after their first positive HIV test) or late testers (those who had had their first positive HIV test one year or less before the diagnosis of AIDS). Chi-square analyses were used to determine the association between characteristics and early or late testing.

Overall, 5,980 participants completed the interview; nearly three-fourths (72%) were men. Fifty-six percent were black, 22% were white and 19% were Hispanic. In 38% of cases, HIV transmission was attributed to male homosexual activity, 36% to heterosexual activity, 17% to injection-drug use and 8% to a combination of male homosexual activity and injection-drug use.

More than two-thirds (69%) of participants had AIDS, whereas nearly one-third had HIV that had not progressed to AIDS. Of the latter, 28% were classified as early testers; the remainder were excluded because of inadequate follow-up time. Among respondents with AIDS, 24% were classified as early testers and 45% were classified as late testers; the 21% who tested positive for HIV more than one year but less than five years before AIDS diagnosis and the 8% for whom it was not possible to determine the relationship between HIV testing and AIDS diagnosis dates were excluded. Late testers were more likely than early testers to be aged 18-29 (odds ratio, 1.7), to be black or Hispanic (1.8-2.2), to have acquired HIV through heterosexual contact (2.4), to have had a high school education or less (1.3-1.4), to ever have been tested for HIV before the first positive result (2.0), to have had confidential testing (3.3), and to have received their first positive result from an HIV testing site or an acute or referral care setting (1.7-4.2). Sixty-five percent of late testers were tested for HIV because of illness; among early testers, 29% were tested because of self-perceived risk and 19% because they wanted to know their HIV status.

The researchers note that "Approximately half of the persons with AIDS had their first positive HIV result [within one] year of AIDS diagnosis, reflecting the need for greater emphasis on earlier diagnosis of HIV infection." They comment that "persons who test late in the course of HIV infection are not able to benefit fully from antiretroviral therapy and pro-phylaxis to prevent opportunistic infections and, thus, are more likely to progress to AIDS."

REFERENCES

(1.) Mack KA and Lansky A, HIV testing-United States 2001, Morbidity and Mortality Weekly Report, 2003 52(23):540-545.

(2.) Nakashima AK et al., Late versus early testing of HIV-16 sites, United States, 2000 2003, Morbidity and Mortality Weekly Report, 2003, 52(25):581-586.