External quality assessment for acid fast bacilli smear microscopy in eastern part of Ethiopia

Abstract

BackgroundExternal quality assessment (EQA) of sputum smear microscopy is essential and indispensable component of any tuberculosis program. This study assessed the EQA of acid fast bacilli (AFB) smear microscopy through onsite evaluation, blinded rechecking and panel test. A one year study was conducted on eight health institution laboratories from December 2011 to December 2012. Onsite evaluation, blinded rechecking and panel tests were used to collect data. Data were analyzed using SPSS version 16. Sensitivity, specificity, predictive values, and proportions of false readings were calculated. The level of agreement was measured using Kappa (κ) value.ResultsProblems observed during onsite evaluation include shortages of materials, disinfectant, and poor storage and working condition. A total of 578 slides were collected for blinded rechecking, of which 102 (17.6 %) were reported as positive by peripheral laboratories. The panel test revealed an overall error of 17 (25.25 %) of which 14 (17.5 %) were minor errors [low false negative 6 (7.5 %) and low false positive 8 (10 %)], and 3 (3.75 %) were major errors (high false positive). The sensitivity, specificity, positive predictive values (PPV) and negative predictive values (NPV) of the peripheral laboratories were 83.5, 97.8, 91.7, and 95.7, respectively. The false readings at the peripheral laboratories were 32 (5.5 %). Agreement on reading the slides was observed on 546 (94.5 %) slides (K = 0.84, SE = 0.054).ConclusionsLack of reagents, supplies, favorable working environment and AFB related technical problems were identified in the peripheral laboratories. High false negative error was found to be the predominant major error. A continuous and strong EQA scheme should be implemented to avoid reporting errors and produce quality sputum results.

Blinded Rechecking of AFB smear Microscopy performance in Selected private health facilities in Tigray, Northern Ethiopia

“…This was comparable with a study indicated 61.5% (13) in DRC [17]. But, higher than other ndings 23.4% in West Amhara, 21% in New delhi and (36.4%) Eastern Ethiopia [12,16,21]. The difference was attributed to methodological difference.…”

“…The smear reading agreement was substantial with kappa value 0.80. Similar ndings indicated in Eastern part of Ethiopia, K=0.84 [21]. In contrast, the agreement was lower than ndings in West Amhara, K=0.97 and Addis Abeba, K=0.87 [20,21].…”

“…Similar ndings indicated in Eastern part of Ethiopia, K=0.84 [21]. In contrast, the agreement was lower than ndings in West Amhara, K=0.97 and Addis Abeba, K=0.87 [20,21]. The national guideline for external quality assessment of AFB smear microscopy indicated a sensitivity of 80% and greater is the optimal performance blinded rechecking smear reading [14].…”

External quality assessment in resource–limited countries

“…Manalebh et al studied three EQA methods to assess AFB smear microscopy performance in Ethiopia: on-site evaluation, blinded rechecking and panel testing; poor staining and low positivity were major factors affecting PT performance ( 49 ). Ayana et al employed similar mixed approaches to assess AFB smear microscopy at university practical attachment sites in Ethiopia; poor working environments were a major contributor to poor performance ( 50 ). Some studies noted re-staining during rechecking at national level significantly improved sensitivity of low-positive AFB smears ( 41 , 51 ).…”

“…EQA schemes are valuable for recognising laboratory errors and identifying underlying problems facing peripheral laboratories ( 50 ), but participation in PT schemes may not by themselves improve performance. Mandy et al and Mukadi et al .…”