Antiretroviral therapy among HIV-infected people who inject drugs in Sweden: access and treatment response

Michele SANTACATTERINA 1, Amanda HÄGGBLOM 2,3, Matteo BOTTAI 1, Rino BELLOCCO 4,5, Anders SÖNNERBORG 2,6,8, Anna Mia EKSTRÖM 7,8
1Unit of Biostatistics, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden 2Unit of Infectious Diseases, Department of Medicine Huddinge, Karolinska Institutet, Stockholm, Sweden 3Department of Infectious Diseases, County Council of Gävleborg, Gävle, Sweden 4Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden 5Unit of Biostatistics, Epidemiology and Public Health, Department of Statistics and Quantitative Methods, University of Milano-Bicocca, Milan, Italy 6Division of Clinical Microbiology, Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden 7Department of Public Health Sciences, Karolinska Institutet, Stockholm, Sweden 8Department of Infectious Diseases, Karolinska University Hospital, Stockholm, Sweden

Background
The objective of our study was to evaluate access to and effectiveness of antiretroviral therapy (ART) among HIV patients infected through injecting drug use (IDU) in Sweden measured as mean CD4 cell count increase over time. We further wanted to investigate the effect of ART on absolute CD4 cell count gain in different age groups.

Methods
This cohort study used prospective observational data from the Swedish InfCare HIV registry, a tool for that serves both as a decision support and a quality of the Swedish HIV care. An amount of 4431 HIV-infected treatment-naïve patients contributed for a total collected amount of 78 082 clinical visits. Time to ART initiation was studied using a Laplace regression model adjusted for possible time-invariant confounders. The mean change of absolute CD4 cell count at time t for each risk group, was studied through a marginal structural model to account for time-varying confounders.

Results
Overall, IDU infected patients in Sweden are diagnosed earlier and consequently start ART later compared with non-IDU. IDU infected experienced a similar increase on mean absolute CD4 cell count compared to the others non-IDU groups.

Conclusions
Patient infected thorough IDU showed a considerable and sustained increasing in mean absolute CD4 cell count, similar to the one from non-IDU. Therefore, a considerable greater effort should be made by policy-makers and clinicians to help people who inject drugs in initiating and adhering ART.

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