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Differences Between Anonymous and Confidential Registrants for HIV Testing -- Seattle, 1986-1992

Human immunodeficiency virus (HIV) counseling and testing is a major component of the public health effort to contain the HIV/acquired immunodeficiency syndrome (AIDS) epidemic. However, persons may avoid HIV testing in part because they fear discrimination and legal sanctions if their drug use, sexual behavior, or test results became public (1,2). Anonymous testing has been offered to address these fears, but it is not clear whether anonymous testing, compared with confidential testing, actually results in testing more persons at risk for or infected with HIV. This report, using registration data from a freestanding HIV-testing clinic in Seattle, compares demographic, behavioral, and serologic characteristics of anonymous and confidential registrants during 1986-1992.

The AIDS Prevention Project (APP), part of the Seattle-King County Department of Public Health, offers HIV counseling and testing targeted to high-risk populations (especially homosexual and bisexual men and injecting-drug users). Since 1986, APP clients have been offered a choice in how they register -- confidentially (using names) or anonymously (using an identifier code generated from birthplace, year of birth, and mother's maiden name).

From June 1986 through March 1992, the APP collected demographic, behavioral, and clinical data on 9993 persons seeking HIV testing. Overall, 4883 (66%) of the 7382 men and 1673 (64%) of the 2611 women registered anonymously. Of all persons seeking testing, 9446 (95.3%) were actually tested; the percentage tested did not differ by sex or registration status. Of 9310 persons who were tested and for whom follow-up information was available, the percentage who returned for results (8724 {93.7%} overall) did not differ by sex. Among 6841 men who were tested and for whom follow-up information was available, there were no differences in the proportions of anonymous or confidential registrants who did not return for results (427 {6.2%}) However, among women who were tested and for whom follow-up information was available, 73 (7.8%) of 930 confidential registrants and 86 (5.6%) of 1530 anonymous registrants did not return for results (p=0.03).

Compared with persons who registered confidentially, both men and women who registered anonymously were older, better educated, and more likely to report middle- or upper-income levels*, and were less likely to test HIV-positive (Tables 1 and 2). Men tested anonymously were somewhat more likely to report having had sex with other men; women tested anonymously were more likely to report heterosexual contact as the primary risk factor. Among all persons tested who were seropositive, 638 (57%) of 1127 men and 28 (49%) of 57 women had registered anonymously.

Reported by: G Goldbaum, MD, T Pearlman, R Wood, MD, L Krueger, MPH, Seattle-King County Dept of Public Health, Seattle. Behavior and Prevention Research Br, Div of Sexually Transmitted Diseases and HIV Prevention, National Center for Prevention Svcs, CDC.

Editorial Note

Editorial Note: Because no HIV vaccine exists, primary HIV-prevention strategies have emphasized education to change behaviors and thereby reduce HIV transmission (3). Counseling accompanying HIV testing can reach high-risk persons when they may be responsive to behavior-change messages. Because there is no cure for HIV infection, secondary prevention strategies have emphasized early diagnosis (to minimize transmission to uninfected partners) and early intervention (to delay the onset of AIDS). Widespread availability of testing is essential to identify asymptomatically infected persons.

HIV counseling and testing programs work only if at-risk clients are willing to be tested for HIV. One determinant of client willingness to be tested appears to be trust that the results of testing will remain confidential (1,2). In one study, offering anonymous testing increased registration rates and decreased the length of time clients waited between deciding to test and going to the testing site (4). Whether the availability of anonymous testing in Seattle increased the number of persons seeking testing cannot be addressed by the study reported here.

Although anonymous and confidential registrants in this study reported similar risk factors and sexual behaviors, confidential registrants were more likely than anonymous registrants to test positive for HIV. However, more persons seeking HIV testing registered anonymously than confidentially. Thus, compared with confidential testing, anonymous testing identified more seropositive men and nearly as many seropositive women.

Because this study was limited to clients at a single HIV-counseling/testing site serving a specific population in one U.S. city, the results may not be generalizable to other clinic types, locations, or patient populations. For example, 83% of those who were tested at this clinic were white; findings may differ for clinics with more racially and ethnically diverse clientele. In addition, the percentage of clients returning for test results at this clinic was much higher than has been found for other sexually transmitted disease (STD) clinics in the United States (possibly because all APP clients requested HIV testing; at other clinics, clients may request other STD services and are advised to have HIV testing). Nonetheless, this study suggests that anonymous testing may be a useful public health strategy that complements confidential testing in identifying persons infected or at increased risk for HIV infection.


  1. Sigel K, Levine MP, Brooks C, Kern R. The motives of gay men for taking or not taking the HIV antibody test. Social Problems 1989;36:368-83.

  2. Weitz R. Anonymity in testing for HIV antibodies desired option. Am J Public Health 1991;81:1213.

  3. Hull HF, Bettinger C, Gallaher MM, et al. Comparison of HIV-antibody prevalence in patients consenting to and declining HIV-antibody testing in an STD clinic. JAMA 1988;260:935-8.

  4. Fehrs LJ, Fleming D, Foster LR, et al. Trial of anonymous versus confidential human immunodeficiency virus testing. Lancet 1988;2:379-82.

*Income defined using federal standards based on family size. In 1991, low income was defined as a monthly income less than $523 and $702 for households of one and two persons, respectively.

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