Impact of introducing light-emitting diode fluorescence microscopy services for diagnosis of pulmonary tuberculosis under Revised National Tuberculosis Control Program India

Context: Light-emitting diode fluorescence microscopy (LED-FM) has been recommended by the WHO and the Government of India over the conventional bright-field microscopy using Ziehl–Neelsen (ZN) staining for the diagnosis of sputum smear-positive tuberculosis (TB) suspects. Aim: The aim of this study was to assess the effectiveness of LED-FM in detecting TB cases. Setting and Design: This retrospective cohort study was carried out in December 2016 using secondary data of the years 2011–2012 from designated microscopy centers (DMCs) at Chandigarh, India. Methodology: Two peripheral DMCs where conventional ZN microscopy was used were taken as controls comparable to two peripheral DMCs which used LED-FM services in programmatic settings. The record of all suspected TB patients who underwent sputum smear examination pre- and post-LED-FM introduction was compared for measuring smear-positive cases, conformational grading, and time taken to read per slide examined. Chi-square was applied to access the statistical significance. Results: Out of total 8850 cases registered after the inception of LED-FM microscopy services, case detection rate was 13.3%, with significant decrease in case detection rate at tertiary level DMCs, there was significant increase in case detection rate at peripheral DMCs operating with LED-FM in contrast to ZN microscopy which was used previously. Scanty grade smear increased significantly by 9.0%. The time taken per slide examination decreased by 57.1% (from 7 min on an average to 3 min on an average) after LED-FM was used. Conclusion: LED-FM is easy to use, takes lesser time to examine slides, and has longer self-life. It also eases laboatory technician's task in reporting scanty grade positives which use to be challenging previously. The results of this study provide enough evidences to scale up the installation process and usage of LED-FM at DMCs for TB diagnosis in Indian settings.