Optimal duration of radiological follow-up for tuberculosis contacts.

Eight hundred and sixty Heaf test positive contacts of cases of tuberculosis in Lothian were offered screening with chest radiographs for the recommended period of two years. In spite of the use of standard methods of encouragement to attend, only 309 (35.9%) completed the two year period of follow-up. Seven cases of tuberculosis (representing a crude rate of eight cases per 1000 contacts) were detected radiologically, all within 3 months of entering the screening programme. In view of the poor compliance with the extended period of follow-up and the detection of all cases early in the screening process, we recommend that, at least in Lothian, radiological follow-up of Heaf positive tuberculosis contacts need only be applied for a period of 6 months.