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

Background: Illicit drug use and homelessness are major contributors to the incidence of tuberculosis (TB) among inhabitants of major cities.

Objective: 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.

Methods: 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.

Results: 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.

Conclusion: 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.