Reducing the Number of Sputum Samples Examined and Thresholds for Positivity: An Opportunity to Optimise Smear Microscopy.

Hdl Handle:
http://hdl.handle.net/10144/20674
Title:
Reducing the Number of Sputum Samples Examined and Thresholds for Positivity: An Opportunity to Optimise Smear Microscopy.
Authors:
Bonnet, M; Ramsay, A; Gagnidze, L; Githui, W; Guerin, P J J; Varaine, F
Journal:
International Journal of Tuberculosis and Lung Disease
Abstract:
SETTING: Urban health clinic, Nairobi. OBJECTIVE: To evaluate the impact on tuberculosis (TB) case detection and laboratory workload of reducing the number of sputum smears examined and thresholds for diagnosing positive smears and positive cases. DESIGN: In this prospective study, three Ziehl-Neelsen stained sputum smears from consecutive pulmonary TB suspects were examined blind. The standard approach (A), > or = 2 positive smears out of 3, using a cut-off of 10 acid-fast bacilli (AFB)/100 high-power fields (HPF), was compared with approaches B, > or = 2 positive smears (> or = 4 AFB/100 HPF) out of 3, one of which is > or = 10 AFB/100 HPF; C, > or = 2 positive smears (> or = 4 AFB/100 HPF) out of 3; D, > or = 1 positive smear (> or = 10 AFB/100 HPF) out of 2; and E, > or = 1 positive smear (> or = 4 AFB/100 HPF) out of 2. The microscopy gold standard was detection of at least one positive smear (> or = 4 AFB/100 HPF) out of 3. RESULTS: Among 644 TB suspects, the alternative approaches detected from 114 (17.7%) (approach B) to 123 cases (19.1%) (approach E) compared to 105 cases (16.3%) for approach A (P < 0.005). Sensitivity ranged between 82.0% (105/128) for A and 96.1% (123/128) for E. The single positive smear approaches reduced the number of smears by 36% compared to approach A. CONCLUSION: Reducing the number of specimens and the positivity threshold to define a positive case increased the sensitivity of microscopy and reduced laboratory workload.
Affiliation:
Epicentre, Paris, France. maryline.bonnet@geneva.msf.org
Publisher:
International Union Against TB and Lung Disease
Issue Date:
Sep-2007
URI:
http://hdl.handle.net/10144/20674
PubMed ID:
17705971
Additional Links:
http://www.ingentaconnect.com/content/iuatld/ijtld
Language:
en
ISSN:
1027-3719
Appears in Collections:
Laboratory; TB

Full metadata record

DC FieldValue Language
dc.contributor.authorBonnet, M-
dc.contributor.authorRamsay, A-
dc.contributor.authorGagnidze, L-
dc.contributor.authorGithui, W-
dc.contributor.authorGuerin, P J J-
dc.contributor.authorVaraine, F-
dc.date.accessioned2008-03-14T08:54:51Z-
dc.date.available2008-03-14T08:54:51Z-
dc.date.issued2007-09-
dc.identifier.citationReducing the Number of Sputum Samples Examined and Thresholds for Positivity: An Opportunity to Optimise Smear Microscopy. 2007, 11 (9):953-8 Int. J. Tuberc. Lung Dis.en
dc.identifier.issn1027-3719-
dc.identifier.pmid17705971-
dc.identifier.urihttp://hdl.handle.net/10144/20674-
dc.description.abstractSETTING: Urban health clinic, Nairobi. OBJECTIVE: To evaluate the impact on tuberculosis (TB) case detection and laboratory workload of reducing the number of sputum smears examined and thresholds for diagnosing positive smears and positive cases. DESIGN: In this prospective study, three Ziehl-Neelsen stained sputum smears from consecutive pulmonary TB suspects were examined blind. The standard approach (A), > or = 2 positive smears out of 3, using a cut-off of 10 acid-fast bacilli (AFB)/100 high-power fields (HPF), was compared with approaches B, > or = 2 positive smears (> or = 4 AFB/100 HPF) out of 3, one of which is > or = 10 AFB/100 HPF; C, > or = 2 positive smears (> or = 4 AFB/100 HPF) out of 3; D, > or = 1 positive smear (> or = 10 AFB/100 HPF) out of 2; and E, > or = 1 positive smear (> or = 4 AFB/100 HPF) out of 2. The microscopy gold standard was detection of at least one positive smear (> or = 4 AFB/100 HPF) out of 3. RESULTS: Among 644 TB suspects, the alternative approaches detected from 114 (17.7%) (approach B) to 123 cases (19.1%) (approach E) compared to 105 cases (16.3%) for approach A (P < 0.005). Sensitivity ranged between 82.0% (105/128) for A and 96.1% (123/128) for E. The single positive smear approaches reduced the number of smears by 36% compared to approach A. CONCLUSION: Reducing the number of specimens and the positivity threshold to define a positive case increased the sensitivity of microscopy and reduced laboratory workload.en
dc.language.isoenen
dc.publisherInternational Union Against TB and Lung Diseaseen
dc.relation.urlhttp://www.ingentaconnect.com/content/iuatld/ijtlden
dc.rightsArchived on this site with the kind permission of the International Union Against TB and Lung Disease, http://www.iuatld.orgen
dc.subject.meshAdulten
dc.subject.meshBacteriological Techniquesen
dc.subject.meshFemaleen
dc.subject.meshHumansen
dc.subject.meshKenyaen
dc.subject.meshMaleen
dc.subject.meshMycobacterium tuberculosisen
dc.subject.meshPredictive Value of Testsen
dc.subject.meshReproducibility of Resultsen
dc.subject.meshSpecimen Handlingen
dc.subject.meshSputumen
dc.subject.meshTuberculosis, Pulmonaryen
dc.subject.meshUrban Populationen
dc.subject.meshWorkloaden
dc.titleReducing the Number of Sputum Samples Examined and Thresholds for Positivity: An Opportunity to Optimise Smear Microscopy.en
dc.contributor.departmentEpicentre, Paris, France. maryline.bonnet@geneva.msf.orgen
dc.identifier.journalInternational Journal of Tuberculosis and Lung Diseaseen

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