Blinded rechecking of sputum smears for acid-fast bacilli to ensure the quality and usefulness of restaining smears to assess false-positive errors

Selvakumar, N and Prabhakaran, E and Rahman, F and Chandu, C A and Srinivasan, S and Santha, T and Chauhan, L S and Narayanan, P R (2003) Blinded rechecking of sputum smears for acid-fast bacilli to ensure the quality and usefulness of restaining smears to assess false-positive errors. International Journal of Tuberculosis and Lung Disease, 7 (11). pp. 1077-1082. ISSN Print: 1027-3719; Online: 1815-7920

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Abstract

SETTING: Microscopy Centres, Velliyur Tuberculosis Unit, Tiruvallur District, Tamil Nadu, India. PROCEDURES: Twelve microscopy centre laboratory technicians examined 41 978 direct sputum smears for acid-fast bacilli. Senior Tuberculosis Laboratory Supervisors (STLS) checked all positive smears (4696) and 10% of negative smears (4776) in an unblinded fashion as per Revised National Tuberculosis Control Programme (RNTCP) guidelines. Ten per cent of the positive and negative slides and another 10% of unchecked negative slides were selected systematically for blinded rereading at the Tuberculosis Research Centre (TRC); 422 slides were reread without and with restaining. RESULTS: Unblinded checking by STLS of the smears read by the laboratory technicians yielded 95 to 100% agreement. Blinded rereading at the TRC revealed that false-negative errors were greater among the laboratory technicians (2–7%) than the STLS (0–3%). Restaining and blinded rereading of slides reduced false-positive errors from 27% to 7%. CONCLUSIONS: Blinded rereading at the reference centre facilitates assessment of laboratory technicians and STLS. Restaining before rereading the smears was found to be useful for precise estimation of false-positive errors.

Item Type:	Article
Uncontrolled Keywords:	pulmonary tuberculosis; quality assurance; sputum smears; acid-fast bacilli; microscopy
Subjects:	Tuberculosis > Laboratory Research > Bacteriological
Divisions:	Basic Science Research > Bacteriology
Depositing User:	Dr. Rathinasabapati R
Date Deposited:	13 Nov 2013 11:16
Last Modified:	09 Mar 2016 11:04
URI:	http://eprints.nirt.res.in/id/eprint/620

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