Chronic lung disease and HIV infection are risk factors for recurrent tuberculosis in a low-incidence setting

SETTING: Programmatic data from the United States on tuberculosis (TB) recurrence are limited. OBJECTIVES: To determine the TB recurrence rate and to determine if chronic lung disease (CLD) and human immunodeficiency virus (HIV) infection are risk factors for recurrence in this population. DESIGN: Nested case-control study among TB cases reported to the Tennessee Department of Health between 1 January 2000 and 31 December 2006. Time at risk for recurrence was through 31 December 2007. Multiple imputation accounted for missing data. RESULTS: Of 1431 TB cases, 20 cases recurred (1.4%, 95%CI 0.9-2.1). Median time at risk for recurrence was 4.5 years (interquartile range 2.7-6.1). Initial and recur-rent Mycobacterium tuberculosis isolates were available for genotyping for 15 patients; 12 were consistent with relapse (0.8%, 95%CI 0.4-1.5) and three with reinfection (0.2%, 95%CI 0.04-0.6). HIV infection (OR 5.01, P = 0.04) and CLD (OR 5.28, P = 0.03) were independently associated with recurrent TB, after adjusting for a disease risk score. HIV infection was a risk factor for TB re-infection (P < 0.001). CONCLUSIONS: In this low-incidence US population, the TB recurrence rate was low, but CLD and HIV were independent risk factors for recurrence. HIV infection was also a risk factor for TB re-infection.