Area-based socio-economic disadvantage and tuberculosis incidence

OBJECTIVE: To examine neighborhood-level influences on tuberculosis (TB) incidence in a multilevel population-based sample. DESIGN: All incident TB cases in Washington State, United States (n = 2161), reported between 1 January 2000 and 31 December 2008 were identified. Multivariate Poisson analysis was used at the ZIP Code tabulation area (ZCTA) level, which allowed for further exploration of area-specific influences on TB incidence. RESULTS: A significant association was found between indices of socio-economic position (SEP) and TB incidence in Washington State, with a clear gradient of higher rates observed among lower ZCTA socio-economic quartiles. Compared to the wealthiest SEP quartile, the relative incidence of TB in successively lower quartiles was respectively 2.7, 4.1 and 10.4 (P trend <0.001). In multivariate analyses, the addition of area-level race, ethnicity and country of birth significantly attenuated this association (adjusted incidence rate ratios 2.3, 2.6, 5.7; P trend <0.001). CONCLUSION: This study found a significant inverse association between area measures of socio-economic status (SES) and TB incidence across ZCTAs in Washington State, even after adjusting for individual age and sex and area-based race, ethnicity and foreign birth. These results emphasize the importance of neighborhood context and the need to target prevention efforts to low-SES neighborhoods.