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

To assess the yield of sputum smear microscopy and sex differences in the National Tuberculosis Control Programme in the north of Vietnam.

Review of registers of 30 randomly selected laboratories (26 district, 4 provincial level).

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.

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.