Screening for infection and disease as a tuberculosis control measure among indigents in New York City, 1994-1997.

Setting: Several social service agencies in New York City, and the Chest Clinic of Bellevue Hospital, a large public hospital.

Objective: To determine the utility of screening as a preventive and control measure among persons at risk for tuberculosis.

Design: Persons seeking social services at several private agencies in New York City were screened, and those with a positive skin test or symptoms suggestive of active tuberculosis were referred to the Chest Clinic for evaluation.

Results: Of 3828 persons evaluated, 20 had active tuberculosis, and 33% of the screened cohort were tuberculin skin test positive. Of 466 persons with tuberculosis infection who were evaluated, only 55 persons were given isoniazid (INH), and only 20 completed preventive therapy. Most patients who were not given INH had taken it previously, were older than 35 years, or had continuing alcohol use which made physicians reluctant to prescribe isoniazid.

Conclusion: Screening for tuberculosis may detect a significant number of cases of active disease when the background prevalence of the disease is very high. However, screening for infection as a means to prevent future cases is unlikely to be effective unless rates of administration and completion of isoniazid preventive therapy are increased.