This study has certain limitations. While other research used only surrogate markers for region of origin, we classified regions of origin based on participants’ nationality,

which is most frequently used for international comparison at present [35]. find more However, use of nationality cannot discriminate between those who have immigrant status and those who have adopted Swiss nationality by marriage, which has important social implications. Another limitation is that it was not possible to make regular comprehensive linkages with the national death registry, for legal and technical reasons. With respect to cohort participation, undocumented immigrants do not even seek medical care in the existing network of HIV practitioners. Therefore, the participation bias is probably still underestimated. The strength of the SHCS is its national representativeness. Of note, a recent comparison with sales data from pharmaceutical companies revealed that 75% of the antiretroviral drugs sold in Switzerland from 2006 to 2008 were prescribed to participants in the SHCS [14]. Further, the nationwide network enabled us to assess cohort nonparticipation. In conclusion, numbers of HIV-infected

immigrants are increasing in the SHCS but immigrants are underrepresented in the SHCS, and are more likely to be lost to follow-up. Our data on nonparticipation, ART status and LTFU suggest that quality of care for immigrants may be less optimal, although healthcare Cisplatin in vivo insurance for all persons living in Switzerland

is mandatory. Thus, qualitative research is needed to analyse underlying reasons for nonparticipation Phospholipase D1 and LTFU of immigrants, also taking into account gender differences. To increase enrolment in the SHCS, enhance adherence to cohort visits and increase ART uptake and adherence to ART, for the benefit of vulnerable groups in Switzerland, and in Europe generally, we propose (i) to motivate immigrants to participate in the cohort and encourage them to remain in the cohort; (ii) to make use of mediators from sub-Saharan Africa with training in the support of people with HIV infection; (iii) to recruit male mediators who are able to follow up African men in a gender-sensitive way; (iv) to obtain information on the structural characteristics of local immigrant communities and enhance the empowerment of immigrants; and (v) to improve the training of Swiss healthcare providers in transcultural competency [36]. We are grateful to all participants in the SHCS, and to the care givers, study nurses and data managers. Furthermore, we thank Martin Gebhardt from the Swiss Federal Office of Public Health for discussing HIV surveillance data with us.