Setting: Governmental health facilities in six districts of India.
Objective: To estimate the prevalence of cough and to compare the detection of smear-positive tuberculosis (TB) among out-patients with cough of > or =2 or > or =3 weeks.
Design: Trained health workers questioned each out-patient for presence of cough. Those with cough > or =2 weeks underwent sputum microscopy.
Results: Of 55561 out-patients interviewed, 2210 (4%) had cough > or =2 weeks, of whom 267 had sputum-positive TB, compared to 182/1370 with cough > or =3 weeks. The 31% who did not spontaneously complain of cough were less likely to be sputum-positive than those who did (45/680 [7%] vs. 222/1530 [15%], P < 0.001), but they accounted for 45/267 smear-positive cases. Using cough > or =2 weeks as the screening criterion, the estimated number of smears performed per day at each primary and secondary health care facility was respectively 8 and 19, compared to 5 and 12 using cough > or =3 weeks.
Conclusion: The detection of smear-positive TB cases can be substantially improved by actively eliciting history of cough from all out-patients, and by changing the screening criterion for performing sputum microscopy among out-patients from cough > or =3 weeks to > or =2 weeks. Before implementing this change nationally, its programmatic feasibility should be assessed.