Tuberculosis screening in health service employees: who needs chest X-rays?

There is uncertainty in the NHS about which individuals should be offered pre-employment screening by chest X-ray and whether this procedure is of value in the detection of tuberculosis. To provide evidence for practice, pre-employment chest X-ray and tuberculin skin test status were examined retrospectively for employees of a health district. Cases were those with an abnormal chest X-ray; referents were a sample of the remainder with a normal chest X-ray. The majority of the population had positive tuberculin skin tests and there was no difference between cases (58 positive out of 68) and referents (170 positive out of 212). Most of the X-ray abnormalities were trivial; four findings were thought significant, but would have caused no problems if undetected and none of these findings was related to tuberculosis. We conclude that in new employees in Hampstead health district, X-ray abnormalities are rare and not predicted by testing tuberculin skin reactivity; neither procedure is justified routinely as a means of screening for tuberculosis. The situation in districts with a high incidence of tuberculosis needs to be investigated.