Geographic analysis of latent tuberculosis screening: A health system approach

Abstract

Background: Novel approaches are required to better focus latent tuberculosis infection (LTBI) efforts in low-prevalence regions. Geographic information systems, used within large health systems, may provide one such approach.

Methods: A retrospective, cross-sectional design was used to integrate US Census and Duke Health System data between January 1, 2010 and October 31, 2017 and examine the relationships between LTBI screening and population tuberculosis risk (assessed using the surrogate measure of proportion of persons born in tuberculosis-endemic regions) by census tract.

Results: The median proportion of Duke patients screened per census tract was 0.01 (range 0-0.1, interquartile range 0.01-0.03). The proportion of Duke patients screened within a census tract significantly but weakly correlated with the population risk. Furthermore, patients residing in census tracts with higher population tuberculosis risk were more likely to be screened with TST than with an IGRA (p<0.001).

Conclusion: The weak correlation between patient proportion screened for LTBI and our surrogate marker of population tuberculosis risk suggests that LTBI screening efforts should be better targeted. This type of geography-based analysis may serve as an easily obtainable benchmark for LTBI screening in health systems with low tuberculosis prevalence.

Fig 1. Number of TSTs and IGRAs placed per month in the Duke University Health System, January 1, 2010 to October 31, 2017.

Fig 2. Provider type ordering TSTs and IGRAs in the Duke University Health System, January 1, 2010 to October 31, 2017.

Fig 3. Regression model for proportion of higher-risk foreign-born living in a census tract and percentage of Duke University Health System patients living in that tract screened with TST or IGRA, January 1, 2010 to October 31, 2017.