Evaluation of Method Modification of Quality Assurance System for Acid Fast Bacilli Microscopic Examination in Hospitals in the North of Thailand 2006

Abstract

A Quality Assurance System has been developed for acid fast bacilli microscopic examination in conjunction with tuberculosis control under DOTS (Directly Observed Treatment, Short Course) strategy in Thailand since 1996 to make good, qualified laboratory diagnoses every year. The improvement of methods such as using one single central control of slide cross-checking at the 10th zonal tuberculosis center, reading slides in time and overtime, using private laboratory units under quality control systems and decreased sending of acid fast bacilli slides from three times to one time per year were implemented and evaluated. The same amount of slide sampling (Lot quality assurance sampling) and the feed-back advisory sheets which were sent to each hospital were done. Evaluation of the number of hospitals sending slides for the quality assurance system and the number of criteria – passing hospitals were calculated and compared with the higher network hospitals’ cross-checking done in 2004 and 2005. The results after the method improvement showed that more of the hospitals have joined our quality assurance system. More slide cross-checking using one center collaborating with a private laboratory unit was done successfully in 90 of 97 hospitals, while the numbers were 50 and 42 in 2004 and 2005 respectively. The decreased slides sending from three times to one time per year was comfortably accepted by the hospitals. There were 75 of 90 hospitals (83%) which passed the criteria. The number of hospitals missing slide readings such as false negative and false positive were 6 (7%). Thirteen hospitals did not send enough slides and one hospital was found to have false negative result errors. So enough manpower and budget to do one center cross-checking, continuous slide sampling and decreased slide sending from three times to one time per year, were the factors of this successful Quality Assurance System. Finally, to continue success in this system, we need collaboration among many parts of the organizations.