Comparative analysis of errors in reading sputum smear microscopy by supervisors and peripheral laboratory technicians in southeastern Nigeria

Abstract

Background: It is important that the quality of microscopy in the peripheral laboratories is monitored in order to provide feedback for improvement of performance of laboratory technicians (LTs). Aim of Study: To compare the errors made in reading sputum smear microscopy for acid-fast bacilli (AFB) by peripheral LTs with those made by secondary level supervisors in the local government areas (LGAs) in the Southeastern states of Nigeria. Materials and Methods: A retrospective study of 15 sputum smear microscopy slides selected systematically from each designated peripheral laboratory and blinded rechecked using the Lot quality assurance (LQA) method between 2006 and 2007 in the southeastern states of Nigeria. Results: The total (major and minor) errors made by both supervisors and peripheral LTs were 189 and 350, respectively. The supervisors made 75 (39.7%) of the total major errors, compared with 114 (60.3%) by peripheral LTs. The supervisors contributed 159 (45.4%) of minor errors, while peripheral LTs contributed 191 (54.6%) of 350. The unpaired Student's t-test values show a statistically significant difference between the mean of high false-positive (HFP), low false-positive (LFP), low false-negative (LF), and quantitative errors, t = 3.794 (P < 0.001); t = 4.146 (P < 0.001); t = 3.059 (P = 0.002) and quantitative errors t = 2.806 (P = 0.005), respectively, between the supervisors and LTs. The exception was in HFN, which was not statistically significant. Conclusion: Although both supervisors and peripheral LTs made both major and minor errors, comparatively supervisors made fewer errors with less variation than the peripheral LTs.