Spirometry Quality Control and Misclassification
P.L. Enright*, M. Studnicka#, J. Zielinski (2005) Spirometry to detect and manage chronic
obstructive pulmonary disease and asthma in the primary care setting. Eur Respir Mon 31,
1–14.
http://www.carefusion.co.uk/pdf/Respiratory/HFOV/ra_ch1.pdf
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“Misclassification rate is around 5% in most research and sub-speciality settings. But
research suggests this is higher in primary care settings. Common cause of error is
inadequate spirometry training and experience of the practitioner.”
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1999
Trained Practitioners-only 3 acceptable blows in 18.9% of tests
Untrained (‘usual) practitioners only 3 acceptable blows in 5.1% of tests
13.5% tests by trained group and 3.4% of untrained group achieved full acceptability
and reproducibility.
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Patrick White,Wun Wong, Tracey Fleming and Barry Gray (2007)
Primary care spirometry: test quality and the feasibility and
usefulness of specialist reporting. British Journal of General Practice
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N=263
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Specialists found:
o 18% cases blow <6seconds
o 8% cases failed to exhale quickly enough
o 18% cases included a second breath/cough
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29% disagreement in interpretation of diagnosis of obstructive disease (primary care
clinicians didn’t interpret FEV1, FVC, FEV1/FVC appropriately)
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8% cases primary care clinicians reported restrictive defects where the criteria were
not met.
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32% disagreement in severity of disease- Primary care clinicians did not adhere to
national criteria for categorisation of obstruction.
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Over 15% of tests sent for reporting were incomplete
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40% of completed tests were deemed unacceptable by specialists.
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There were also 49 tests without spirometry indices/flow loops/both; which when
added to unacceptable tests provides a total of 52% tests deemed unacceptable.
C.E. Bolton, A.A. Ionescu, P.H. Edwards, T.A. Faulkner,
S.M. Edwards, D.J. Shale (2005) Attaining a correct diagnosis of COPD
in general practice. Respiratory Medicine 99, 493–500
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determined by questionnaire the availability, staff training, use and the
interpretation results of spirometry in 72% of general practices in Wales
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Most practices had a spirometer (82.4%) and used it (85.6%)
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Confidence in use and interpretation of results varied widely: 58.1% were confident
in use and 33.8% confident in interpretation
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Spirometry was performed more often if confident in use and interpretation (both
Po0:001) and was related to greater training periods (Po0:001).
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Of the 125 patients previously diagnosed with COPD (without Spirometry), 61 had
spirometric confirmation, while 25 had reversible obstruction (range 210–800 mls),
34 had normal and 5 had restrictive spirometry.
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Summary; only 49% of 125 patients were correctly diagnosed with COPD. 51%
were incorrectly diagnosed
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Conclusion: Despite incentives to perform spirometry in general practice, lack of
adequate training in use and interpretation suggests use is confounded and the
diagnosis of COPD is likely to be made on imprecise clinical grounds.