Codes are hierarchically structured, therefore please indicate most detailed code as possible.

Code	Ethnicity of patient
100	White/Caucasian
110	> White, European
200	Black
204	> Other Black
210	> Sub-Saharan African
220	> Caribbean
230	> African-American
250	> Black, African
300	Hispanic/Latinx
400	Asian
405	> Other asian
410	> East Asian (e.g. Chinese, Japanese)
411	> > Chinese
412	> > Japanese
420	> Southeast Asia (e.g. Thai, Vietnamese, Philippino)
421	> > Indian Subcontinent (Indian, Pakistani, Bangladeshi)
430	> South Asian (e.g. Indian, Pakistani)
800	Other ethnic groups
810	> Maghrebian
820	> Middle East/Arab
830	> Turkish
840	> Roma people/Gypsy (whichever is term is acceptable)
850	> Indigenous people from Americas or Alaska Native
860	> Indigenous people from other continents/locations
900	Mixed race/ethnicity
910	Do not want to disclose
980	Prohibited
999	Unknown

The definition of ethnicity is complex and there is no ideal definition for all countries and for all times. Likewise is the definition of race and though conceptually different from ethnicity, they are often used interchangeably. As described by many authors, ethnicity is a fluid and imprecise concept heavily influenced by societal views. If definition of ethnicity is complex, inevitably its categorization will be complex too. The definition and categorization used in HICDEP acknowledges these limitations and aims by no means to solve the intense international debate of this issue but to provide a homogeneous and practical approach for HIV research. We have partially used existing administrative classifications as they provide the advantage to have, in some instances, census population denominators but are invariably too detailed for practical use in the context of HICDEP.

We suggest users to ask themselves “why is this variable necessary to answer my research question?” to avoid some of the common mistakes highlighted in the publications below which have attributed to exclusively biological and/or genetic traits differences heavily influenced by the profound social, cultural and political differences inherent to those categories. We aim to provide a standardized definition that, in addition to the information on country or region of birth already collected within HICDEP, can be used by cohort studies of HIV infected people from different countries. Therefore, in order to encompass these different scenarios, some terms may have little meaning for some settings. Finally, this classification allows for multiple options and whenever possible, should be based on the patients’ self-identification.

1. Ahdieh L, Hahn RA. Use of the terms ‘race’, ‘ethnicity’, and ‘national origins’: a review of articles in the American Journal of Public Health, 1980–1989. Ethnicity and Health 1996; 1:95–8
2. Bhopal R. Glossary of terms relating to ethnicity and race: for reflection and debate. J. Epidemiol. Community Health 2004; 58:441–445
3. Cooper RS, Kaufman JS, Ward R. Race and Genomics. N Engl J Med 2003; 348; 12: 1166-1170
4. European Centre for Disease Prevention and Control. Improving HIV data comparability in migrant populations and ethnic minorities in EU/EEA/EFTA countries: findings from a literature review and expert panel. Stockholm: ECDC; 2011.​www.ecdc.europa.eu