BUFFY COAT IN DIAGNOSIS OF PULMONARY TUBERCULOSIS

Background: Besides charging the patients with outstanding costs, tuberculosis (TB) causes high mortality and morbidity in a country. We studied the sensitivity, specificity, positive and negative predictive values as well as the efficiency of buffy coat smear test in patients who were pulmonary TB suspects. This research was conducted at Massih Daneshvari Hospital, National Research Institute of Tuberculosis and Lung Disease (NRITLD). Materials and Methods: According to clinical and radiographic records of 50 pulmonary TB suspects, five ml of blood along with smear and culture of sputum were collected. The research method was a clinical trial (Diagnostic test type), and the technique was of observational-interview type. Six buffy coat smears were obtained by Ficoll-Hypaque sedimentation method while the samples were stained by ZiehlNeelsen stain. Results: On sputum examination, 32 patients (64%) were B.K positive while 22 (44%) had positive sputum culture for Mycobacterium tuberculosis. Buffy coat was positive in 4 patients (8%). In comparison with sputum smear and culture, buffy coat had sensitivity of 12.5% and 13.6%, specificity of 100% and 96.4%, positive predictive value of 100% and 75%, negative predictive value of 39.4% and 58.7%, efficiency of 44% and 60% respectively. Conclusion: In regard to the high specificity of buffy coat as compared to sputum smear (100%) and sputum culture (96.4%), it is possible to consider buffy coat as a method for screening tuberculosis patients that cannot expectorate sputum. Since buffy coat method has a high positive predictive value as compared to sputum smear (100%), it could replace other unavailable accurate methods like sputum culture and PCR and be used as a substitution for sputum smear. (Tanaffos