P24. A high rate of HIV-1 acquisition post immigration among migrants in Sweden determined by a CD4+ T-cell decline trajectory model

Gaetano Marrone1, Johanna Brännström1, Veronica Svedhem1, Ujjwal Neogi2, Anders Sönnerborg1,2
Affiliates: 1Unit of Infectious Diseases, Department of Medicine Huddinge, Karolinska Institutet, and Department of Infectious Diseases, Karolinska University Hospital, Stockholm, Sweden 2Division of Clinical Microbiology, Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden.

Background
There is a lack of knowledge about to which extent migrants are HIV-1 infected after arrival to the European countries. Complementary methods are therefore warranted for this assessment. Objective of this study was to assess to which extent migrants to Sweden become HIV-1 infected post-immigration using a CD4+ T-cell decline trajectory model.

Methods
All migrants (n=2,268), ≥ 15 years, diagnosed with HIV-1 1983 to 2013, with a known year of arrival to Sweden and without primary HIV infection or mother to child transmission, were included. The CD4+ T-cell decline trajectory model was applied and estimates of HIV acquisition were compared to the clinical reports. A multinomial logistic regression model assessed the characteristics of patients among whom the estimates were discordant. Phylogenetic analysis was performed in a subset of patients to explore whether this would favor the model or the doctor’s estimate.

Results
The model estimated 19% to be infected after arrival to Sweden whereas the physician´s estimate was 12%. In 79% of cases the estimates agreed. Discordance was predominantly seen when the doctor estimated HIV acquisition before arrival to Sweden, while the model estimated after arrival to Sweden, and occurred in 10% of all patients. The probability of a discordance increased with age and high first CD4+ T-cell counts, while it was lower for people who inject drugs and men who have sex with men compared to those heterosexually infected. The phylogenetic analysis showed a higher concordance with the CD4 model than with the clinical reports (36% vs 13%).

Conclusions
A substantially higher proportion of migrants are infected after arrival to Sweden as compared to estimated by clinical routine reports. It is therefore important to further emphasize primary preventive measures among migrants who have established themselves in their new country.

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