Testing language effects in psychiatric epidemiology surveys with randomized experiments: results from the National Latino and Asian American Study.

To evaluate the prevalence of mental disorders for persons of non-English-language origin, it is essential to use translated diagnostic interviews. The equivalence of translated surveys is rarely tested formally. In the National Latino and Asian American Study (NLAAS), the authors tested whether a carefully translated mental health survey administered in Spanish produced results equivalent to those obtained by the original English version, using a randomized survey experiment. The NLAAS is a nationally representative survey carried out in the United States in 2002-2003. Bilingual respondents from the Latino section of the NLAAS (n = 332) were randomly assigned to receive either a Spanish- or English-language version of the World Mental Health Survey Composite International Diagnostic Interview. In tests of differences in lifetime and 12-month prevalences of 11 diagnoses and four higher-order aggregate disorder categories, in only one case was there an apparent difference between randomized language groups: Lifetime reports of generalized anxiety disorder were more prevalent in the bilingual group assigned to English than in the group interviewed in Spanish. Detailed follow-up analyses did not implicate any specific question in the generalized anxiety disorder protocol. Translation and back-translation of surveys does not guarantee that response probabilities are exactly equivalent. Randomized survey experiments should be incorporated into cross-cultural psychiatric surveys when possible.