Low utilization of targeted tuberculosis (TB) infection testing in the United States: a 15-year serial cross-sectional study

Objective In California, 82% of new tuberculosis (TB) cases occur among people born in TB-endemic countries. Guidelines recommend targeted TB infection (TBI) testing based on risk factors (e.g., birth in a TB-endemic country, immunosuppression), but comprehensive evaluations of testing practices are limited. Methods We conducted a serial cross-sectional study of adult Kaiser Permanente Northern California members from 2008 to 2023 to assess TBI testing and factors associated with testing and interferon gamma release assay (IGRA) use. Results Of 6,572,233 adults, 1,405,896 (21.4%) were tested for TBI. However, 78.1% of tests were among people without TB risk factors. The overall testing rate improved slightly from 5.21 per 100 in 2008 to 6.71 in 2023. People born in TB-endemic countries had 25.2% (24.8-25.5%) lower prevalence of testing compared to US-born persons. Other risk factors were associated with higher testing including close TB contact (aPR = 2.67 [2.63-2.71]), homelessness (aPR = 1.36 [1.33-1.38]), and HIV infection (aPR = 3.58 [3.53-3.63]). Among those tested, individuals from TB-endemic countries were 63.2% (62.0-64.4%) more likely to receive an IGRA than US-born persons. Conclusions Despite guideline recommendations, TBI testing disproportionately overlooks people born in TB-endemic countries while over testing those without risk factors, highlighting a critical gap between evidence and practice.