Risk Factors for Tuberculosis and Homelessness Often Overlap in U.S.

Risk factors for tuberculosis in the United States overlap with many of the risk factors associated with persistent homelessness, including being male or having a history of incarceration or substance abuse, according to a report in the June 8 issue of JAMA, a theme issue on tuberculosis.

Homelessness is associated with an increased risk of exposure to Mycobacterium tuberculosis, undetected and untreated infection, and subsequent progression to TB disease, according to background information in the article. In 1993, the Centers for Disease Control and Prevention (CDC) standardized national monitoring of TB disease among homeless persons by asking health departments to indicate whether annually reported TB cases occurred in homeless persons, the authors note. Thus, 1994 through 2003 represents the first full decade of national TB surveillance that includes an assessment of homelessness.

Maryam B. Haddad, MSN, MPH, FNP, and colleagues from the CDCs Division of Tuberculosis Elimination, analyzed data of all verified TB cases reported into the National TB Surveillance System from 50 states and the District of Columbia from 1994 through 2003 to compare risk factors and disease characteristics between homeless and nonhomeless persons with TB.

The authors note that because the U.S. Census Bureau does not have data on the number of homeless people in the United States they were unable to use the surveillance data to determine rates of TB disease among the homeless and instead calculated the proportion of all reported TB cases that occurred in homeless persons.

Of 185,870 cases of TB disease reported between 1994 and 2003, 11,369 were among persons classified as homeless during the 12 months before diagnosis, the authors report. The annual proportion of cases associated with homelessness was stable (6.1 percent 6.7 percent). The authors found a higher proportion of TB cases associated with homelessness in western and some southern states. Most homeless persons with TB were male (87 percent) and aged 30 to 59 years. Black individuals represented the highest proportion of TB cases among the homeless and non-homeless. The proportion of homeless persons with TB who were born outside the United States (18 percent) was lower than that for non-homeless persons with TB (44 percent). At the time of TB diagnosis, nine percent of homeless persons were incarcerated. The authors continue, Compared with non-homeless persons, homeless persons with TB had a higher prevalence of substance use (54 percent alcohol abuse, 29.5 percent non-injected drug use, and 14 percent injected drug use), and 34 percent of those tested had co-infection with human immunodeficiency virus. Most of the TB cases in homeless persons were managed by health departments (81 percent) and 86 percent of those cases used directly observed therapy where healthcare professionals watched the patients take their medications.

The most urgent priority for controlling TB in the United States is interrupting new transmission of M tuberculosis. Opportunities for transmission arise when homeless persons with infectious TB frequent homeless shelters, emergency departments, and jails, the authors write. Once diagnosed, however, homeless TB patients received good case management, including laboratory diagnostic evaluation, appropriate use of a 4-drug regimen, and excellent treatment outcomes for persons given DOT [directly observed therapy] (recommended for all TB patients). Controlling this public health problem demands considerable resources but is integral to responding to the Institute of Medicines call to eliminate TB in the United States, the authors conclude.

Reference: JAMA. 2005;293:2762-2766.