Using principal component analysis to build an acculturation index for identifying Asian ethnic enclaves in California

Level of acculturation may be considered a potential predictor of cancer risk, as traditional Asian diets and other health behaviors have been associated with cancer, and cultural values contribute to health care decision making. Block group level data from the US 2000 Census were used to develop an acculturation scale for Asian cancer patients. Four Census variables from California block groups (N=22,133) were chosen to be combined into a single acculturation score using principal components analysis: the percentage of population that were Asian, that were linguistically isolated with an Asian language, that spoke limited English and an Asian language, and that were recent immigrants (arrived within the last 10 years). Scores were discretized by quintiles into a 5-point index, with index 1 meaning the most acculturation among residents of a block group and index 5 meaning the least acculturation. Address at diagnosis was geocoded for 98.1% of Asian cancer cases (all cancer sites) in CCR diagnosed between 1996 and 2004 (N=99,431) to Census block groups, and each case was assigned the acculturation index of the Census block group they lived in at time of diagnosis. This acculturation index was significantly associated with individual acculturation measures, such as race, nativity, age at SSN issue and language preference and use. This acculturation index has begun to serve as a valuable data resource within the California Cancer Registry for researchers to identify ethnic enclaves and for investigating patterns of disease by community acculturation.