Methods and baseline characteristics of two group-randomized trials with multiracial and multiethnic working-class samples

Few papers address the methodological challenges in recruiting participants for studies of cancer prevention interventions designed for multiracial and multiethnic working-class populations. This paper reports the results of the sample selection and survey methods for two group-randomized intervention studies. The two group-randomized intervention studies, Healthy Directions-Small Business (HD-SB) and Healthy Directions-Health Centers (HD-HC), included a worksite-based study in 26 small manufacturing businesses and a study in 10 outpatient health centers. We used selection and recruitment methods to obtain a multiracial and multiethnic working-class study sample. In 2000 and 2001, we assessed baseline measures of sociodemographic characteristics and behavioral outcomes by self-report. We then computed intraclass correlation coefficients (ICCs). Of the 1740 participants in the HD-SB study, 68% were non-Hispanic whites, and 76% had working-class occupations. In the HD-HC study, 59% of 2219 participants were non-Hispanic whites. Among those who worked, 51% had working-class occupations. Large percentages of both samples reported not meeting recommended guidelines for the target behaviors. For example, 86% of members of both samples consumed fewer than the recommended five servings of fruits and vegetables per day. The ICCs for the four target behaviors in HD-SB were between 0.006 and 0.02. In the HD-HC study, the ICCs ranged from 0.0004 to 0.003. The two studies were successful in recruiting multiracial and multiethnic working-class participants. Researchers will find the estimates of the primary outcomes and their ICCs useful for planning future studies.