Evaluation of symptom screening methods for tuberculosis: a secondary analysis of a nationwide tuberculosis prevalence survey in Mongolia

Symptom screening for tuberculosis (TB) is a key component for identifying TB suspects and TB cases, particularly in resource limited countries. This study aimed to evaluate the effectiveness of symptom screening using TB related symptoms including the standard symptom screening criterion of cough for two weeks or more, to identify TB cases in the general population. This study is a secondary analysis of the nationwide population based, cross sectional survey for TB prevalence in Mongolia in 2014 2015. Each TB related symptom was compared between bacteriologically confirmed TB cases and bacteriologically negative participants. Of the 50,309 adults who received symptom screening, 248 were diagnosed as bacteriologically confirmed TB cases. The sensitivity and specificity of standard symptom screening of cough for two weeks or more were 20.6% and 95.3%, respectively. The higher sensitivity and lower specificity were reported in sputum for two weeks or more (22.2% and 93.6%, respectively), in fever for four days or more (21.4% and 95.0%, respectively), in weight loss (36.3% and 89.3%, respectively), in combination with standard symptom screening. TB cases had more\nchronic cough: cough for two weeks or more” (OR 2.78, 95% CI: 1.83 4.22), “chronic sputum: sputum for two weeks or more” (OR 1.67, 95% CI: 1.06 2.65), “fever for four days or more” (OR 3.46, 95% CI: 1.90 6.28) and “weight loss” (OR 3.73, 95% CI:\nEvaluation of symptom screening methods for tuberculosis\n4\n2.77--5.02). The addition of TB--related symptoms, namely, chronic sputum, fever and weight loss to chronic cough, which is the standard symptom screening criterion, may facilitate the detection of more TB cases efficiently.