Evaluation of sputum smear microscopy in the National Tuberculosis Control Programme in the north of Vietnam

OBJECTIVE: To assess the yield of sputum smear microscopy and sex differences in the National Tuberculosis Control Programme in the north of Vietnam. METHODS: Review of registers of 30 randomly selected laboratories (26 district, 4 provincial level). RESULTS: The average daily workload per technician was 4.4 examinations in district and 5.3 examinations in provincial laboratories. To find one smear-positive case, 9.7 suspects were examined and 29.3 smears done. The smear-positive rate (mean 10.3%) was higher among men (11.6%) than among women (8.4%, P < 0.001). There were more men than women among tuberculosis (TB) suspects (male:female ratio 1.36, 95%CI 1.19-1.54), but even more so among smear-positive patients (1.89, 95%CI 1.64-2.14), irrespective of specimen quality and number of smears examined. Three smears were examined for 18 055 suspects (61.7%). The incremental gain was 33.5% and 4.9% for the second and third smear examination, respectively; 186 (95%CI 160-221) smears needed to be examined to find one additional case of TB with a third serial examination. CONCLUSION: The diagnostic process seemed generally efficient. The male:female ratios suggest higher TB incidence in men rather than lower access to TB facilities for women. The third smear examination could be omitted.