Prevalence of pulmonary tuberculosis among respiratory symptomatic subjects in an out-patient primary health unit

SETTING: Out-patient primary health unit (OPHU) in Rio de Janeiro City, Brazil. OBJECTIVE: To evaluate the impact on the detection of tuberculosis (TB) cases of reducing the time of respiratory symptoms from 'cough ≥3 weeks' to 'cough ≥1 week' as a criteria for TB case finding among individuals visiting an OPHU for any other reason. DESIGN: Cross-sectional study. RESULTS: During the period of the study, 10.7% (765/ 7174) of subjects reported cough ≥1 week. Among 542 subjects enrolled in the study with cough ≥1 week, 15 (2.7%) cases were diagnosed with pulmonary tuberculosis (PTB, 2767/100 000). The probability of detecting TB in the OPHU setting among subjects seeking care for respiratory symptoms was significantly higher than among those presenting to the OPHU for other reasons (OR 31.5, 95%CI 4.1-241.9; P < 0.0001). The probability of identifying TB among patients seeking care due to respiratory symptoms was not influenced by the duration of cough (P = 0.7). CONCLUSION: These findings suggest that the screening criteria for TB case finding of cough for less than the usual 3 weeks among patients who attend a health facility due to respiratory symptoms in settings with a high prevalence of TB may significantly improve the proportion of TB cases diagnosed.