EXTERNAL QUALITY ASSESSMENT (EQA) FOR DIRECT SPUTUM SMEAR MICROSCOPY (DSSM). FOR ACID FAST BACILLI (AFB) IN STATE OF PERAK ...
EXTERNAL QUALITY ASSESSMENT (EQA) FOR DIRECT SPUTUM SMEAR MICROSCOPY (DSSM) FOR ACID FAST BACILLI (AFB) IN STATE OF PERAK (2010) 1Lim
Jia Min, 1Tan Kim Ling, 1Murugan a/l Kuppusamy, 1Nur’ Akma Ibrahim, 1Suhaila Abdul Rahman, 1Fatimah Ramli, 2Puvaneswari a/p Subramaniam, 1Zulhainan Hamzah and 1Mohamed Naim Abdul Kadir 1Ipoh
Public Health Laboratory (IPHL), Ministry of Health Malaysia, Jalan Jelapang, 30020 Ipoh, Perak Darul Ridzuan, Malaysia 2Unit TB/Kusta, Jabatan Kesihatan Negeri Perak, Jalan Panglima Bukit Gantang Wahab, 30590 Ipoh, Perak Darul Ridzuan, Malaysia ABSTRACT Considering the importance of External Quality Assessment (EQA), we evaluated the performance of direct sputum smear microscopy (DSSM) carried out in 2010 for State of Perak, Malaysia. A total of 9,587 AFB slides collected from 86 microscopy centres were analysed. Analysis showed 99.87% (9,574) of AFB slides were in good agreement with only 0.13% (13 slides) were considered as false reading. Assessment on general quality, cleanliness and proper staining showed an average of > 75% of the AFB slides were prepared accordingly. However, the quality of sputum smear prepared in terms of achieving the standardised size (3cm x 2cm sizes, evenness and thickness showed an average of < 55% in quality. INTRODUCTION Case finding through sputum microscopy (DSSM) is one of the elements of directly observed therapy, short course (DOTS) strategy - WHO strategy for management of tuberculosis (TB) (WHO, 2001). Thus, TB control requires a functional laboratory set-up with quality diagnostic services and a trained diagnostician and a microscopist. However, the performance of such laboratories depends on continuous monitoring and quality improvement mechanisms put in place (WHO, 1994). Therefore, the principal objective of EQA is to standardize sputum microscopy for the detection of infectious TB cases across the peripheral diagnostic centers and to validate the reported acid-fast bacilli (AFB) microscopy results from these centers. In addition EQAs will further identifies inappropriate procedures, out-ofdate reagents, uncontrolled instrumentation, and /or training needs of incompetent or untrained staff . The National Tuberculosis and Leprosy Control Program, MOH recommends the rechecking of a sample of routine slides as a method of ensuring the quality of diagnosis and classification of TB patients within the health services. This thus leads to the importance of establishing a proper system for standardization of procedures and identification of poor performing peripheral microscopy centers. Therefore, EQA program has been established at Ipoh Public Health Laboratory (IPHL) to monitor the performance of each individual peripheral microscopy centers in State of Perak, Malaysia. In this report, the performance of DSSM for AFB in 86 peripheral microscopy centers in State of Perak at 2010 is presented.
RESULTS Of the 9,587 AFB slides evaluated, a total of 99.87% or 9,574 of AFB slides were in good agreement while only 0.13% (13 slides) were identified as false reading, of which 0.02% (2 slides) were considered as false positive reading, while another 0.11% (11 slides) were false negative (Graph 1). Assessment on general quality of AFB slides showed an average of 75.48% (7,236 slides) were in good quality. The quality of good staining showed an average of 78.87% (7,561 slides) while 21.14% (2026 slides) were poor, which includes 16.88% (1,618 slides) were under-stained and 4.26% (408 slides) were over-stained. The percentage of good cleanliness were 76.82% (7,365 slides) while 23.18% (2,222 slides) were poor (Graph 2). Further analysis shows 61.33% (5880 slides) of sputum smear were prepared according to the standard size recommended (3 cm x 2 cm) were) while another 38.66% (3,707 slides) of which 26.73% (2,563 slides) and 1,144 (11.93%) slides were prepared smaller and larger than the standardised size, respectively. Assessment on thickness of sputum smear prepared, only 55.8% (5,350 slides) achieved proper thickness while 44.19% (4,237 slides) were not (36.17% (3,468 slides) thin and 8.02% (769 slides) thick smear). The quality for evenness of sputum smear prepared was only 47.74% (4,577 slides) while 52.26% (5,010 slides) were poor (Graph 2).
Fig. 1
DISCUSSION A total of 86 microscopy centers from 9 districts in Perak State were involved in EQA programme organized by IPHL in 2010. Assessment of DSSM among districts showed District of Hilir Perak has been identified as the best DSSM for AFB performance in 2010 (data not shown). The percentage of false reading oberved was still low compared to other studies, some studies have reported false positive results of as high as 6.9% and a false negativity of 3.4%, as reported by Buzingo et al., 2003. Nevertheless, it is important to note that since the number of slides evaluated represents only 11.73% (9,587 slides) of the total slides (81,744 slides) prepared in 2010, the actual number of error cases could be much more. Therefore, it is important that every error reading and poorly prepared slide should not be overlooked and related problems must be resolved as soon as possible. We have also identified few peripheral laboratories that did not even score well in achieving the standardised size (3cm x 2cm) of sputum smear, and also for evenness and thickness of the smear prepared. A good quality smear (Figure 1) is produced by a proper coiling technique and staining method. Immediate action has been taken up to improve this situation such as by reinforce the practising of smear techniques by a regular on-the-job training for microscopist and regular visits by Pengelola TB Negeri and Scientific Officers. CONCLUSION ,. The performance of DSSM for AFB in the peripheral laboratories of the State of Perak was generally satisfactory. Therefore, it is important to note that a well organized EQA programme, coupled with a systematic and regular on-the-job training and supportive supervision by Ipoh Public Health Laboratory will greatly improve and strengthen the performance of DSSM in future.
Percentage (%)
METHODS A total of 9,587 AFB slides were collected based on statistically valid sampling procedure - Lot Quality Assurance Sampling (LQAS) from 81,744 AFB sputum smear prepared in 86 microscopy centres in State of Perak for year 2010. Assessment of DSMM were carried out as described in the External Quality Assessment for AFB Smear Microscopy (EQA-IUATLD/WHO). Several parameters were included in the assessment such as error detection, general quality, quality of staining, cleanliness , size , thickness and evenness of sputum smears prepared. Identified peripheral microscopy centers with poor performance, immediate on-site evaluation and corrective action will be done by Pengelola TB Negeri. In addition, regular training and re-fresher courses were also organized by Ipoh Public Health Laboratory (IPHL) to reinforce the standardized method for Direct sputum smear microscopy (DSSM) for acid fast bacilli (AFB).
90 80 70 60 50 40 30 20 10 0
EXTERNAL QUALITY ASSESSMENT (EQA) FOR DIRECT SPUTUM SMEAR MICROSCOPY (DSSM) FOR ACID FAST BACILLI (AFB) STATE OF PERAK Graph 2 75.48
78.87
76.82 61.33
52.26 47.74
38.66 24.52
General Quality
21.14
Staining
55.8 44.19
23.18
Cleanliness
Size
Evenness
Thickness
Good
75.48
78.87
76.82
61.33
47.74
55.8
Poor
24.52
21.14
23.18
38.66
52.26
44.19
Acknowledgement National Public Health Laboratory (NPHL) , Sungai Buloh, Selangor
