The use of income information of census enumeration area as a proxy for the household income in a household survey
BACKGROUND The study objective was to investigate the association between health outcomes and several small-area-based socioeconomic measures and also with individual socioeconomic measures as a check on external validity. METHODS Cross-sectional design based on the analysis of the Barcelona Health Interview Survey of 1992. A representative stratified sample of the non-institutionalised population resident in Barcelona city (Spain) was obtained. The present study refers to the 4171 respondents aged over 14. We studied perceived health status, presence of chronic conditions and smoking as health outcomes. Area socioeconomic measures (1991 census) were generated at census tract level and individual socioeconomic measures were educational level and social class obtained through the survey. RESULTS With individual socioeconomic measures we observed that the lower the educational level or social class, the higher the probability of reporting a perceived health status of fair, poor or very poor and of presenting some chronic condition. With regard to smoking, among men this trend was similar [odds ratio (OR) = 1.5; 95% confidence interval (CI) = 1.2-1.9 in social classes IV-V with respect to social classes I-II], while among women it was reversed (OR = 0.7; 95% CI = 0.5-0.9). With the different area-based socioeconomic indicators differences were also observed in this sense, with the exception of smoking in women for which these indicators do not show any differences by socioeconomic level. CONCLUSIONS With several census area-based socioeconomic measures similar effects on inequalities in health have been observed. In general, these inequalities were in the same sense as those obtained with individual-based measures. Small-area-based socioeconomic measures from the Spanish census could greatly enhance analysis of social inequalities in health, overcoming the absence of socioeconomic data in public health registries and in medical records.