Disparities in testing for latent tuberculosis infection in a large US integrated healthcare system

Disparities in latent tuberculosis infection (LTBI) testing by birth country and socioeconomic status (SES) are not well understood. We used electronic health records from Kaiser Permanente Southern California (2010-2019) to examine disparities in LTBI testing across SES among those born in high-vs. low-tuberculosis (TB) incidence countries.

Retrospective cohort study.

We examined LTBI testing rates and measures of disparities (absolute/relative concentration index, between-group variance, and mean log deviation) across area-level SES and racial/ethnic groups, by birth in a high-vs. low-TB incidence country, with imputed data for missing birth country.

We included 1,740,428 individuals, with a median age of 37.0 years (interquartile range 27.0, 51.0), who were 50.3% female (n = 875,879), and 39.2% Hispanic (n = 682,870); 1,205,853 (69.3%) were born in a country with low TB incidence. Among adults born in low-TB incidence countries (n = 1,205,853; 315.3 tests/10,000 person-years), testing rates remained stable (annual percent change [APC] = -0.69% [95% CI: -1.55, 0.41]). Among adults born in high-TB incidence countries (n = 534,575; 246.7 tests/10,000 person-years), testing rates increased over time (APC = 1.90% [1.14, 2.90]) with a higher rate of increase for those with higher SES. Among individuals born in a high-TB incidence country, disparities by SES and racial/ethnic groups increased over time.

Disparities in LTBI testing in individuals born in high-vs. low-TB incidence countries decreased overall, but increased disproportionally in those with higher SES among those born in high-TB incidence countries. Continued research is needed to understand the causes of disparities, and to inform interventions to reduce disparities.