Chest radiography and tuberculosis case-finding in Western Australia

A retrospective study to assess the role of chest radiography (CR) in the control of tuberculosis (TB) in Western Australia (WA) was carried out by reviewing the annual reports from 1948 to 1983 and analysing the records at the Perth Chest Clinic (PCC) for a 12-month period in 1992-93. Mass miniature radiography in WA was introduced in 1948 and was selective up to 1951, yielding 3.3 cases of active TB per 10(3) films and accounting for 18.3% of the total notifications. It became a compulsory statewide screening procedure from 1952 to 1972. During this period the average yield was 0.7 cases/10(3) films and they accounted for 19.6% of the notifications. Thereafter the examination was again selective, detecting 0.2 cases/10(3) films and accounting for 2.7% of the notifications for 1977-79. From 1 July 1992 to 30 June 1993, a total of 2456 asymptomatic persons had chest X-ray records at the PCC relating to contact tracing (456), positive Mantoux reaction (330), pre-employment clearance as child-care workers (616) and application for permanent residence (1054). Overall, their X-rays were reported as normal in 95.4%, abnormal and of clinical significance in 2.7% and abnormal but of no significance in 1.9%. Active TB was detected in 0.2%, giving a yield of 2.4 cases/10(3) films and accounting for 10% of the notifications for the 12-month period. This study shows that mass CR, when judiciously applied, can contribute significantly to TB case-finding even in low-prevalence countries where the goal is the elimination of the disease.