3, 990 HIV-infected patients in a large study of HIV infection in Denmark. The authors matched each HIV-infected patient with up to 99 noninfected people in the general population to assemble a group of 379, 872 population controls. The controls had the same sex, date of birth, and geographic residence as the HIV-infected patient to which they were matched. Of note, unlike the United States, Denmark provides treatment with HAART free of charge to citizens with HIV infection.