Evaluation of sensitivity and specificity of tuberculosis diagnostic tools among HIV positive patients: A cross-sectional study

Abstract

Background & Aim: Tuberculosis is the major cause of morbidity and mortality among HIV patients. Thus, early diagnosis of Tuberculosis among these patients is important. The purpose of the present study was to determine the Sensitivity, Specificity, PPV and NPV for tools of diagnosing TB among HIV patients referred to behavioral disorder counseling center of Shiraz city. Methods & Materials: In this cross sectional study, 250 HIV+ patients in Shiraz were evaluated. For each patient, three sputum smears and a Chest X-ray and PPD was taken. Sensitivity, specificity, and positive and negative predictive values were determined based on the results of sputum cultures as a gold standard. Results: Among 250 HIV+ individuals who entered the study, 8 (3.2 %) were diagnosed with tuberculosis. The sensitivity, specificity, PPV and NPV for chest x-ray were 62.5%, 96%, 38% and 98.7%, respectively. Also they were 62.5%, 98.7%, 62.5% and 98.7% for AFB 1, and 25%, 99.5%, 66% and 97.5% for AFB 2. Finally, these factors were 99.5%, 99.5%, 66% and 97.5% for AFB 3. Conclusion: The prevalence of TB among HIV+ patients referring to the behavioral disease counseling center in Shiraz was lower than in other endemic areas of developing countries. The screening tools for diagnosis of tuberculosis included the chest x-ray and Acid Fast Bacilli and PPD test in order to find out the important role of detecting TB disease among HIV-infected people.

Keywords

• co-infection
• HIV/AIDS
• sputum culture
• sputum smear
• Tuberculosis