NO CHANGE IN INCIDENCE AND PREVALENCE OF HIV AMONG INTRAVENOUS-DRUG-USERS IN COPENHAGEN FROM 1985 TO 1990

During the years 1984 to 1990, 1,029 intravenous drug users (IVDU), eq ualling approximately one-third of the estimated total IVDU population in the study area, attended the outpatient venereal disease clinic of Copenhagen for an HIV antibody test. Neglecting samples on HIV-positi ve persons after the first positive test, 665 IVDU were only tested on ce, whereas 364 IVDU had 613 tests performed after their first HIV ant ibody negative result. HIV prevalences calculated for each year showed that the prevalence of 20% in 1985 was significantly higher than thos e of the following years, varying between 9% and 12% without any stati stical differences between these years or evidence of an increase or a decrease. HIV incidence was calculated from the results of the 364 IV DU with an initially negative HIV test, from whom 613 subsequent test results were available and of which 20 showed HIV antibodies. The tota l risk period was 837 years, and the overall incidence 2.4 per 100 per son years without any difference between male and female IVDU, but wit h a tendency of a decreasing incidence with increasing age. The incide nce rates per 100 person years were 2.82 in 1984-1987 and 2.38 in 1988 -1990, which is not significantly different. A seroconversion rate of 2.42 (1.51-3.65) per 100 IVDU per year was calculated. With an estimat ed IVDU population of 3,000 persons in Copenhagen, the yearly number o f new HIV infected IVDU can then be estimated to 72 persons (45-110), a figure that is 100% higher than that known from the anonymous nation al HIV reporting system. It is concluded that the overall HIV antibody prevalence among IVDU in Copenhagen stabilized from the year 1986 is unchanged due to a rather high and unchanged HIV incidence in spite of the almost unlimited access to free needles, syringes, and condoms fo r IVDU in Denmark. Incidence studies are crucial in monitoring the HIV epidemic and necessary in measuring the effect of national HIV campai gns.