Individualized and institutionalized residential place-based discrimination and self-rated health: a cross-sectional study of the working-age general population in Osaka city, Japan

Background: Several studies have reported that individualized residential place-based discrimination (PBD) affects residents' health. However, studies exploring the association between institutionalized PBD and health are scarce, especially in Asian countries including Japan. Methods: A cross-sectional study was conducted with random two-stage sampling of 6191 adults aged 25-64 years in 100 census tracts across Osaka city in 2011. Of 3244 respondents (response rate 52.4%), 2963 were analyzed using multilevel logistic regression to examine the association of both individualized and institutionalized PBD with self-rated health (SRH) after adjustment for individual-level factors such as socioeconomic status (SES). An area-level PBD indicator was created by aggregating individual-level PBD responses in each tract, representing a proxy for institutionalized PBD, i.e., the concept that living in a stigmatized neighborhood affects neighborhood health. 100 tracts were divided into quartiles in order. The health impact of area-level PBD was compared with that of area-level SES indicators (quartile) such as deprivation. Results: After adjustment for individual-level PBD, the highest and third area-level PBD quartiles showed odds ratio (OR) 1.57 (95% credible interval: 1.13-2.18) and 1.38 (0.99-1.92), respectively, for poor SRH compared with the lowest area-level PBD quartile. In a further SES-adjusted model, ORs of area-level PBD (highest and third quartile) were attenuated to 1.32 and 1.31, respectively, but remained marginally significant, although those of the highest area-level not-home-owner (census-based indicator) and deprivation index quartiles were attenuated to 1.26 and 1.21, respectively, and not significant. Individual-level PBD showed significant OR 1.89 (1.33-2.81) for poor SRH in an age, sex, PBD and SES-adjusted model. Conclusion: Institutionalized PBD may be a more important environmental determinant of SRH than other area-level SES indicators such as deprivation. Although it may have a smaller health impact than individualized PBD, attention should be paid to invisible and unconscious aspects of institutionalized PBD to improve residents' health.