Authors
1
Disease Control Department, I.R. IRAN,
2
Coordinator of TB, Rudsar
3
National Research Institute of Tuberculosis and Lung Disease, Shaheed Beheshti University of Medical Sciences and Health Services, TEHRAN-IRAN
Abstract
Background: One of the most important subjects for health services is the estimation of the prevalence of pulmonary tuberculosis (particularly sputum – smear positive pulmonary tuberculosis cases). We suppose that there is a possible correlation between the prevalence of chronic cough and the sectional prevalence of pulmonary tuberculosis. Materials and Methods: A cross-sectional study was carried out in Rudsar in the year 1999. Rudsar is a town with a total population of 82658, 19505 families, which includes 2018 (2.44%) people, having history of more than 2 weeks cough, based on our census. Individuals with more than 2 weeks cough were eligible for this study. Tuberculosis suspects were referred to district health center, for each suspicious case, diagnostic procedures such as physical chest examination evaluation of BCG status, three sputum smears and, if needed, CXR were performed. Results: Of 2018 individuals, 594 (29.4%) had typical scar of BCG. Chronic cough was confirmed by clinical work up in 761 participants. Among them, 403 patients (0.47% of Rudsar population) presented with productive cough sputum specimens were taken. Chest radiographs showed characteristic pulmonary tuberculosis lesions in 13(16.7%) of 79 patients in whom radiography was done on the basis of clinical findings. Five patients were diagnosed as sputum-smear positive pulmonary tuberculosis, and 3 new smear cases were diagnosed as new smear- negative TB cases. Sectional prevalence of sputumsmear positive patients and pulmonary tuberculosis between March 21 and June 20, 1999 were 8.5 and 12.1 in 100000 population respectively. If patients who were diagnosed within 9 months after the end of our study, according to health service system census, are taken into consideration, these rates will run to 30.25 and 47.12 respectively. Sensitivity, specificity, Positive Predictive Value (PPV), and Negative Predictive Value (NPV) for sputum smear and chest radiography were 62.5%, 100%, 100%, 94.4% and 100%, 92.9%, 61.5%, 100% respectively. In regard to diagnostic role of sputum – smear and chest radiograph in pulmonary TB, the difference between PPV (p=0.000), specificity (p= 0.03) and sensitivity (p = 0.000) was significant. Likelihood ratio for chest radiograph (34.26) was greater than sputum-smear (23.66)(p =0.000). Conclusion: Only 20% of the patients with pulmonary tuberculosis were identified via health service system (HSS) screening method in Rudsar, and the rest were diagnosed through recent study. Our findings suggest that the diagnostic power of chest radiograph is more than sputum smear; however, we think the HSS method for taking sputum wasn’t a controlled one. (Tanaffos 2003; 2(8): 65-70)
Keywords
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