[Participation and representation of the immigrant population in the Spanish National Health Survey 2011-2012].
OBJECTIVE
Population health surveys have been the main data source for analysis of immigrants' health status in Spain. The aim of this study was to analyze the representation of this population in the Spanish National Health Survey (SNHS) 2011-2012.


METHODS
We analyzed methodological publications and data from the SNHS 2011-2012 and the population registry. Differences in the participation rate between the national and foreign populations and the causes for these differences were analyzed, as well as the representation of 11 countries of birth in the survey with respect to the general population, with and without weighting.


RESULTS
Households with any foreign person had a lower participation rate, either due to a higher error in the sampling frame or to a higher non-response rate. In each country of birth, the sample was smaller than would be expected according to the population registry, especially among the Chinese population. When we applied the sample weights to the 11 countries of birth, the estimated population volume was closer to the estimated volume of the population registry for all the countries considered, although globally both the underrepresentation and the intranational bias remained.


CONCLUSIONS
The lower participation of the immigrant population and differences in participation depending on the country of origin suggest the existence of a potential bias in the SNHS, which should be taken into account in studies analyzing the health of this population. The lower participation rate should be studied in greater depth in order to take appropriate measures to increase the representativeness of health surveys.
Departamento de Sociología 2, Facultad de Ciencias Sociales y de la Comunicación, Universidad del País Vasco UPV/EHU, Leioa (Vizcaya), España. Electronic address: yolanda.gonzalezr@ehu.es.
Yolanda
Y
González-Rábago
Departamento de Sociología II, Facultad de Ciencias Económicas y Empresariales, Universidad de Alicante, Alicante, España.
Daniel
D
La Parra
Departamento de Sociología 2, Facultad de Ciencias Sociales y de la Comunicación, Universidad del País Vasco UPV/EHU, Leioa (Vizcaya), España; Grupo de Trabajo de Determinantes Sociales de la Salud de la Sociedad Española de Epidemiología.
Unai
U
Martín
Grupo de Trabajo de Determinantes Sociales de la Salud de la Sociedad Española de Epidemiología; Agència de Salut Pública de Barcelona (IIB-Sant Pau), Barcelona, España; CIBER de Epidemiología y Salud Pública (CIBERESP), España.
Davide
D
Malmusi
D000293:Adolescent; D000328:Adult; D000368:Aged; D002681:China / Q000208:ethnology; D003256:Community Participation; D054242:Emigrants and Immigrants / Q000706:statistics & numerical data; D005060:Europe / Q000208:ethnology; D005191:Family Characteristics; D005260:Female; D006306:Health Surveys / Q000706:statistics & numerical data*; D006801:Humans; D007843:Latin America / Q000208:ethnology; D008297:Male; D008875:Middle Aged; D009018:Morocco / Q000208:ethnology; D015983:Selection Bias; D012959:Socioeconomic Factors; D013030:Spain; D055815:Young Adult
Emigrantes e inmigrantes; Emigrants and immigrants; Encuestas de salud; España; Health surveys; Selection bias; Sesgo de selección; Spain