Tuberculosis among drug users and homeless persons: impact of voluntary X-ray investigation on active case finding

Illicit drug use and homelessness are major contributors to the incidence of tuberculosis (TB) among inhabitants of major cities. The primary objective of this study was to establish a sustainable low-threshold chest X-ray screening programme for pulmonary TB among illicit drug users and homeless persons and to integrate this into the existing public health programme for active case finding. A secondary objective was to estimate the coverage of the programme, assess other risk factors and determine TB rates and treatment outcome in these two groups. Illicit drug users and homeless persons were asked to voluntarily participate in an X-ray screening programme. The coverage of the intervention, total number and characteristics of cases and the follow-up of treatment were assessed. A total of 4,529 chest radiographs were made from 3,477 persons, of whom 66% were homeless and 34% were illicit drug users, between May 2002 and April 2007. Coverage for screening once every 2 years ranged between 18 and 26%. Thirty-nine TB cases (14 drug users, 25 homeless persons) were identified, representing 8.7% of the total case load of 448 notified cases of pulmonary TB in Frankfurt during this period. Among the drug users, human immunodeficiency virus coinfection (10/14) seemed to play a key role in the development of TB. The case-finding rate of 861/100,000 radiographs (1,122/100,000 persons) is as high as that in routine contact investigations (1,078/100,000). Among all individuals with TB, 76% completed treatment. A novel targeted TB screening approach with voluntary radiographic examination of illicit drug users and homeless persons can be integrated into the existing public TB prevention programme and provides a high case-finding rate.