A multiethnic cohort in Hawaii and Los Angeles: Baseline characteristics

The authors describe the design and implementation of a large multiethnic c ohort established to study diet and cancer in the United States. They detai l the source of the subjects, sample size, questionnaire development, pilot work. and approaches to future analyses. The cohort consists of 215,251 ad ult men and women (age 45-75 years at baseline) living in Hawaii and in Cal ifornia (primarily Los Angeles County) with the following ethnic distributi on: African-American (16.3%), Latino (22.0%), Japanese-American (26.4%), Na tive Hawaiian (6.5%), White (22.9%), and other ancestry (5.8%). From 1993 t o 1996, participants entered the cohort by completing a 26-page, self-admin istered mail questionnaire that elicited a quantitative food frequency hist ory, along with demographic and other information. Response rates ranged fr om 20% in Latinos to 49% in Japanese-Americans. As expected, both within an d among ethnic groups, the questionnaire data show substantial variations i n dietary intakes (nutrients as well as foods) and in the distributions of non-dietary risk factors (including smoking, alcohol consumption, obesity, and physical activity). When compared with corresponding ethnic-specific ca ncer incidence rates, the findings provide tentative support for several cu rrent dietary hypotheses. As sufficient numbers of cancer cases are identif ied through surveillance of the cohort, dietary and other hypotheses will b e tested in prospective analyses.