Objective: The aim of the study was to examine whether exposure to abacavir increases the risk for myocardial infarction (MI).Design, setting and subjects: This was a prospective nationwide cohort study which included all Danish HIV‐infected patients on highly active antiretroviral therapy (HAART) from 1995 to 2005 (N=2952). Data on hospitalization for MI and comorbidity were obtained from Danish medical databases. Hospitalization rates for MI after HAART initiation were calculated for patients who used abacavir and those who did not. We used Cox's regression to compute incidence rate ratios (IRR) as a measure of relative risk for MI, while controlling for potential confounders (as separate variables and via propensity score) including comorbidity.Main outcome: Relative risk of hospitalization with MI in abacavir users compared with abacavir nonusers.Results: Hospitalization rates for MI were 2.4/1000 person‐years (PYR) [95% confidence interval (CI) 1.7–3.4] for abacavir nonusers and 5.7/1000 PYR (95% CI 4.1–7.9) for abacavir users. The risk of MI increased after initiation of abacavir [unadjusted IRR=2.22 (95% CI 1.31–3.76); IRR adjusted for confounders=2.00 (95% CI 1.10–3.64); IRR adjusted for propensity score=2.00 (95% CI 1.07–3.76)]. This effect was also observed among patients initiating abacavir within 2 years after the start of HAART and among patients who started abacavir as part of a triple nucleoside reverse transcriptase inhibitor (NRTI) regimen.Conclusions: We confirmed the association between abacavir use and increased risk of MI. Further studies are needed to control for potential confounding not measured in research to date.

To estimate mortality rates and prognostic factors in HIV-positive patients who started combination antiretroviral therapy between 1996–1999 and survived for more than ten years. We used data from 18 European and North American HIV cohort studies contributing to the Antiretroviral Therapy Cohort Collaboration. We followed up patients from ten years after start of combination antiretroviral therapy. We estimated overall and cause-specific mortality rate ratios for age, sex, transmission through injection drug use, AIDS, CD4 count and HIV-1 RNA. During 50,593 person years 656/13,011 (5%) patients died. Older age, male sex, injecting drug use transmission, AIDS, and low CD4 count and detectable viral replication ten years after starting combination antiretroviral therapy were associated with higher subsequent mortality. CD4 count at ART start did not predict mortality in models adjusted for patient characteristics ten years after start of antiretroviral therapy. The most frequent causes of death (among 340 classified) were non-AIDS cancer, AIDS, cardiovascular, and liver-related disease. Older age was strongly associated with cardiovascular mortality, injecting drug use transmission with non-AIDS infection and liver-related mortality, and low CD4 and detectable viral replication ten years after starting antiretroviral therapy with AIDS mortality. Five-year mortality risk was <5% in 60% of all patients, and in 30% of those aged over 60 years. Viral replication, lower CD4 count, prior AIDS, and transmission via injecting drug use continue to predict higher all-cause and AIDS-related mortality in patients treated with combination antiretroviral therapy for over a decade. Deaths from AIDS and non-AIDS infection are less frequent than deaths from other non-AIDS causes.

Shortly after AIDS was recognized in USA, the first cases were diagnosed in Denmark.^1,2 Today Denmark has a population of 5.3 million citizens and the prevalence of HIV infection in the adult population is estimated at ∼0.07%.^3,4 Denmark's HIV epidemic is characterized by the ‘western world pattern’ in which the main transmission routes in the 1980s were between men who had sex with men (MSM), with later spread to heterosexual groups. Since 1995 mortality in the Danish HIV population has fallen drastically as a consequence of highly active antiretroviral therapy (HAART), followed by an increase in HIV prevalence.⁵ HIV incidence has been rather stable. Denmark's tax-funded health care system provides treatment, including antiretroviral therapy, free-of-charge to all HIV-positive residents. The treatment of HIV-infected patients occurs only in eight specialized medical centres.

The mortality in patients with persistent low CD4 count despite several years of HAART with sustained viral suppression is poorly documented. We aimed to identify predictors for inadequate CD4 cell recovery and estimate mortality in patients with low CD4 count but otherwise successful HAART.

A national survey for chronic hepatitis C has not been performed in Denmark and the prevalence is unknown. Our aim was to estimate the prevalence of chronic hepatitis C from public registers and the proportion of these patients who received specialized healthcare.

The DHCS is a cohort of all HIV-infected individuals seen in one of the eight Danish HIV centres after 31 December 1994. Here we update the 2009 cohort profile emphasizing the development of the cohort. Every 12-24 months, DHCS is linked with the Danish Civil Registration System (CRS) in order to extract an age- and sex-matched comparison cohort from the general population, as well as cohorts of family members of the HIV-infected patients and of the comparison cohort. The combined cohort is linked with CRS, the Danish Cancer Registry, the Danish National Hospital Registry, the Danish Registry of Causes of Death, the Danish National Prescription Registry, the Attainment Register and the Integrated Database for Labour Market Research to get information on vital status, migration, cancer, hospital contacts, causes of death, dispensed prescriptions, education and employment. Using this design, rates of a range of outcomes have been compared between HIV-infected patients and the comparison cohort, as well as between families of these two cohorts in order to disaggregate the effects of HIV infection and familial/environmental factors. Data can be shared with foreign institutions following approval from the Danish Data Protection Agency. Potential collaborators can contact the study director, Niels Obel (e-mail: niels.obel@regionh.dk).