Area-level socioeconomic disadvantage and severe pulmonary tuberculosis: U.S., 2000-2008

Lower socioeconomic status (SES) is associated with increased risk of tuberculosis (TB) and diagnostic delays, but the extent to which this association reflects an underlying gradient in advanced status of pulmonary TB is unknown. We conducted a multilevel retrospective cohort analysis examining the relationship between socioeconomic characteristics and pulmonary TB disease status, as measured via sputum smears and chest radiography results.

We included 862 incident TB patients reported in King County, Washington, from 2000-2008. We abstracted patient-level measures from charts and surveillance data. We obtained socioeconomic characteristics of TB patients, as well as those of the areas where TB patients lived, from the 2000 U.S. Census. A socioeconomic position (SEP) index was derived to measure SES.

Of those with known results, 814 of 849 patients (96%) displayed abnormal radiography findings. A total of 239 graded patients (39%) had positive smears, 136 (57%) of whom had grades of moderate (3+) or numerous (4+) acid-fast bacilli. In unadjusted analyses, patients living in lower SEP areas did not appear to have higher probabilities of more advanced disease. In multivariate models adjusting for individual demographic and socioeconomic measures, as well as area-based demographic variables, block-group SEP was not significantly associated with more advanced pulmonary disease.

Lower SEP was not significantly associated with greater pulmonary disease severity after controlling for individual age, race, sex, and origin, and block-group race, ethnicity, and origin. These findings suggest that the severity of pulmonary TB at diagnosis is not synonymous with delayed diagnosis.