Evaluation of T-SPOT® Serology Test for the Diagnosis of Pulmonary Tuberculosis

Background : tuberculosis is a chronic contagious infectious disease which is fatal within 5 years in more than half of cases if not diagnosed. Since the fight against tuberculosis is based on early diagnosis and complete treatment of all TB patients, useful biochemical methods are emphasized to find a more rapid diagnostic method. This study aims to evaluate the impact of diagnostic value of T-SPOT® serology in patients suspected or diagnosed with tuberculosis admitted in Bou-Ali Hospital of Zahedan, Iran.
Materials and Methods : The descriptive-analytic study conducted on 60 patients, 30 of whom had AFB sputum smear positive pulmonary tuberculosis, and 30 patients had AFB sputum smear negative pulmonary tuberculosis. The results were stated as sensitivity, specificity, positive and negative predictive value and likelihood ratio using conventional epidemiological table.
Results : In 23 out of 30 patients with AFB sputum smear positive pulmonary tuberculosis, T-SPOT® serology became positive and in 12 out of 30 patients with AFB sputum smear negative pulmonary, T-SPOT® serology became positive. According to the epidemiological table in this study, sensitivity, specificity, positive and negative predictive value and likelihood ratio of this test were determined respectively 76%, 40%, 56%, 63% and 1.25%.
Conclusion : According to the results, this test is not able to distinguish active pulmonary tuberculosis from latent infection. Moreover, considering high contact of regional people with TB patients and pulmonary involvement of people due to factors other than TB, the test value with this likelihood ratio is low.