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.