HIV testing in Denmark: a nominator-denominator study

In order to describe prevalence and trends of HIV infection, demographic variables, risk factors, and reasons for seeking testing, and self-administered anonymous questionnaire was distributed to approximately 75% of all individuals tested for antibodies to HIV on a voluntary basis, in all parts of the Danish health-care system, in November 1987 and in April 1988. The number of questionnaires returned was 2143 (55%). Overall, HIV prevalence was 1.2% and was highest among homosexual and bisexual men: 6% in November and 9% in April, with no statistical difference. Sixteen per cent of the men reported homosexual behaviour, 7% reported intravenous drug use, and 60% more than one opposite-sex partner within the last 12 months. No substantial difference was observed between reported risk factors in November and April. Overall, 18% had been tested at least once before; this figure rose to approximately 50% among homosexual men and intravenous drug abusers, a substantial number of whom had engaged in risk behaviour since the latest test. Sixty percent of men and 75% of women were tested at general practitioners', and 22% and 13% at sexually transmitted disease clinics; only 6% of men and 3% of women had used alternative test sites. It is concluded that studies of anti-HIV-tested people can give detailed information about patterns of HIV testing and indications of trends in HIV infection rates, thereby supplementing other forms of HIV surveillance.