Increased risk of tuberculosis among foreign-born persons with diabetes in California, 2010-2012

Background: Diabetes increases the risk of tuberculosis. We sought to identify populations of persons with diabetes in California at further increased risk for tuberculosis to target tuberculosis infection screening and treatment efforts. Methods: We performed a retrospective population-based analysis of adult (aged >= 18 years) tuberculosis cases reported in California during 2010-2012. Tuberculosis cases with and without diabetes were grouped into regions of birth and stratified by age category. Population estimates were calculated using 2011-2012 California Health Interview Survey data. We calculated tuberculosis disease rate and relative risk of tuberculosis among persons with diabetes stratified by birth location and age group; and the number needed to screen and, if positive, treat for tuberculosis infection to prevent one case of active tuberculosis over 5 years (NNS). Results: During 2010-2012, among 6,050 adults with active tuberculosis in California, 82% were foreign-born and 24% had diabetes. The overall relative risk for tuberculosis among persons with diabetes was 3.5 (95% confidence interval, 3.3-3.7) with a rate of 21 per 100,000 persons with diabetes. The rate among foreign-born persons with diabetes (141.5/100,000) was almost 12 times greater than among nonforeign-born persons with diabetes (12.0/100,000). The NNS was 7,930 among all adults, 2,740 among adults with diabetes, 1,526 among all foreign-born adults, and 596 among foreign-born adults with diabetes. Conclusions: In California, foreign-born persons with diabetes had significantly elevated rates of active tuberculosis. Focusing tuberculosis infection screening and treatment efforts on foreign-born persons with diabetes may be a feasible and efficient way to make progress toward tuberculosis elimination in California.