Screening for TB infection among a high risk inner-city population: Is it efficacious?

The majority of cases of tuberculosis (TB) in the U.S. are due to reactivation of latent infection. We prospectively evaluated the efficacy of TB screening and preventive therapy (PT) among a high risk inner-city population in Atlanta. Patients accessing care at a variety of sites in Atlanta including GMH ER and selected clinics, Mercy Mobile Health Care clinics for the homeless, as well as the Atlanta City Jail were offered a tuberculin skin test (TST) and if positive were evaluated for PT and started on INH if indicated. All services were free. Over a 2 year period, 7246 inner-city residents had a TST placed and 65% returned to have the TST read at 48-72 hours. Demographics of the population screened were as follows: 82.7% were black, 12.8% were white, and 4.5% were of other race/ethnicity. Median age was 35 years, 94.9% were bom in the USA, and 62.5% were male. 809 (17.2%) of the 4701 that returned to have the TST read had a positive test. No cases of active TB were diagnosed. 409 (50.5%) of the 809 with a positive TST had an indication for PT per ATS/CDC guidelines. 310 started PT and 84 (27.1% of those that started PT, 10.4% of those with an indication for PT, 1.2% of the total screened) completed at least 6 mo of INH. In multivariate analysis factors associated with a higher completion rate included: foreign birth (OR=4.1, 95%CI 1.8-9.3) and age >65 (OR=6.0, 95%CI 1.4-24.5); those screened in jail were less likely to complete PT (OR=0.3, 95%CI 0.1-0.6). In summary, we were able to screen a large number of inner-city residents for TB, have most return to have the TST read and noted a significant proportion had TB infection. However, only a fraction of those screened completed PT. Large scale screening of a high risk population does not appear to be efficacious given limited resources and competing priorities of TB control programs; a more targeted approach is indicated.