Same-Day Diagnosis versus the Conventional ‘Spot-Morning-Spot’ Using Ziehl-Neelsen and Fluorescent Microscopy: A Cross-Sectional Study

Abstract

Introduction: Diagnosis of spot-morning-spot (SMS) smear microscopy is inconvenient for patients, who have to make multiple visits to health facilities to submit multiple sputum specimens over two days and may visit also for an extra day to collect the result. Optimization of smear and microscopy will decrease the inconvenience of the patients and possibly increase the detection rate. Objective: To determine the sensitivity, specificity and predictive values of a proposed “same day" strategy of one-day diagnosis of tuberculosis (TB) and compare it to the conventional method, as culture is reference standard. Methods: A cross-sectional study was conducted from June to August, 2013 from University of Gondar Hospital [UoGH] and Debretabor Rural Hospital [DTH], North West Ethiopia. A total of 180 TB suspected patients were enrolled. Patients suspected for TB submitted SMS samples [conventional method]. One additional sample was collected ≥1h after the first sputum (the proposed same-day method) and one sample selected and cultured. Open Epi data & Mc Nemar’s tests were used to compare the test. Result: The sensitivity of the conventional method (27/160) was 81.8%, 95%CI (65.6-91.4) and that of proposed spot method (25/160), was 75.8%, 95%CI (58.9- 87.2) by Ziehl-Neelson (ZN) but the difference was statistically significant; P-value = 0.298.  Their specificity was similar 100 % (97.1-100); P-value = 1.00. The light emitted diode (LED-FM) sensitivity was 84.9% (69.1- 93.4) Vs 81.8% (65.6- 91.4) in conventional and proposed method respectively. The difference of sensitivity wasn’t significant; P-value=0.568. The specificity was [84.9 %(69.1-93.4) Vs 81.8 %(65.6-91.4)] conventional Vs proposed same day method respectively; P- value=0.155. Conclusion and Recommendation: Since the sensitivity and specificity was statistically non-difference in conventional and proposed spot-next spot specimen of ZN and LED-FM method, but 6% difference in sensitivity in ZN methods. This difference happens in two cases, this may be due to poor sample preparation (especially first-day next spot smear). But this study shows, it is possible to diagnosis PTB in one day by giving extensive and comprehensive training for laboratory technicians and technologist, and the practicability needs further research.