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Efficient screening for COPD using three steps: a cross-sectional study in Mexico City.

Franco-Marina F, Fernandez-Plata R, Torre-Bouscoulet L, García-Sancho C, Sanchez-Gallen E, Martinez D, Perez-Padilla R, Study Te - NPJ Prim Care Respir Med (2014)

Bottom Line: Underdiagnosis of chronic obstructive pulmonary disease (COPD) in primary care can be improved by a more efficient screening strategy.We analysed two related Mexico City cross-sectional samples.A three-step screening strategy for COPD substantially reduces the need for spirometry testing when only a COPD scale is used for screening.

View Article: PubMed Central - PubMed

Affiliation: Department of Epidemiology, National Institute of Respiratory Diseases, Mexico City, Mexico.

ABSTRACT

Background: Underdiagnosis of chronic obstructive pulmonary disease (COPD) in primary care can be improved by a more efficient screening strategy.

Aims: To evaluate a three-step method of screening for COPD consisting of an initial short questionnaire followed by measurement of forced expiratory volume in 1s/forced expiratory volume in 6s (FEV1/FEV6) using an inexpensive pocket spirometer in those with high risk, and diagnostic quality spirometry in those with a low FEV1/FEV6.

Methods: We analysed two related Mexico City cross-sectional samples. The 2003 Mexico City PLATINO survey (n=542) was used to develop a short questionnaire to determine the risk of COPD and a 2010 survey (n=737) additionally used a pocket spirometer. The discriminatory power of the two instruments was assessed with receiver operator characteristic (ROC) curves using three COPD definitions.

Results: The developed COPD scale included two variables from a simple questionnaire and, in ROC analysis, an area under the curve (AUC) between 0.64 and 0.77 was found to detect COPD. The pocket spirometer had an AUC between 0.85 and 0.88 to detect COPD. Using the COPD scale as a first screening step excluded 35-48% of the total population from further testing at the cost of not detecting 8-18% of those with COPD. Using the pocket spirometer and sending those with a FEV1/FEV6<0.80 for diagnostic quality spirometry is very efficient, and substantially improved the positive predictive value at the cost of not detecting one-third of COPD cases.

Conclusions: A three-step screening strategy for COPD substantially reduces the need for spirometry testing when only a COPD scale is used for screening.

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Related in: MedlinePlus

Bland–Altman plot comparing: (a) the FEV1/FEV6 (%) obtained from Vitalograph COPD-6 6-SS with that obtained from pre-bronchodilator spirometry, (b) FEV1/FEV6 (%) from COPD-6 with that obtained in the laboratory from the flow-volume calibration syringe. Horizontal dotted lines at about 10 and 20 indicate the limits of agreement of the % FEV1/FEV6 difference (within 2 standard deviations of the mean difference). The line over the points corresponds to the median band of the % FEV1/FEV6 difference.
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fig3: Bland–Altman plot comparing: (a) the FEV1/FEV6 (%) obtained from Vitalograph COPD-6 6-SS with that obtained from pre-bronchodilator spirometry, (b) FEV1/FEV6 (%) from COPD-6 with that obtained in the laboratory from the flow-volume calibration syringe. Horizontal dotted lines at about 10 and 20 indicate the limits of agreement of the % FEV1/FEV6 difference (within 2 standard deviations of the mean difference). The line over the points corresponds to the median band of the % FEV1/FEV6 difference.

Mentions: FEV1/FEV6 values obtained from the pocket spirometer had a poor intraclass correlation: 0.26 comparing 6-second spirometry results with pre-BD spirometry (95% confidence interval, 0.19–0.33, mean difference +5.1%) and 0.34 comparing 6-second spirometry results with post-BD diagnostic spirometry (95% confidence interval, 0.27–0.41, mean difference +3.7%, see Figure 3). The Bland–Altman plot showed that extreme differences in FEV1/FEV6 between the two devices (more than twice the s.d.) were frequent (Figure 3). In addition, the pocket spirometer produced lower values for this ratio at values of 90% and higher. This latter finding was also observed in a laboratory linearity check comparing COPD-6 measurements with a flow-volume calibrator (Flow-Volume Calibrator; Jones Medical Instruments, Oak Brook, IL, USA).


Efficient screening for COPD using three steps: a cross-sectional study in Mexico City.

Franco-Marina F, Fernandez-Plata R, Torre-Bouscoulet L, García-Sancho C, Sanchez-Gallen E, Martinez D, Perez-Padilla R, Study Te - NPJ Prim Care Respir Med (2014)

Bland–Altman plot comparing: (a) the FEV1/FEV6 (%) obtained from Vitalograph COPD-6 6-SS with that obtained from pre-bronchodilator spirometry, (b) FEV1/FEV6 (%) from COPD-6 with that obtained in the laboratory from the flow-volume calibration syringe. Horizontal dotted lines at about 10 and 20 indicate the limits of agreement of the % FEV1/FEV6 difference (within 2 standard deviations of the mean difference). The line over the points corresponds to the median band of the % FEV1/FEV6 difference.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4373258&req=5

fig3: Bland–Altman plot comparing: (a) the FEV1/FEV6 (%) obtained from Vitalograph COPD-6 6-SS with that obtained from pre-bronchodilator spirometry, (b) FEV1/FEV6 (%) from COPD-6 with that obtained in the laboratory from the flow-volume calibration syringe. Horizontal dotted lines at about 10 and 20 indicate the limits of agreement of the % FEV1/FEV6 difference (within 2 standard deviations of the mean difference). The line over the points corresponds to the median band of the % FEV1/FEV6 difference.
Mentions: FEV1/FEV6 values obtained from the pocket spirometer had a poor intraclass correlation: 0.26 comparing 6-second spirometry results with pre-BD spirometry (95% confidence interval, 0.19–0.33, mean difference +5.1%) and 0.34 comparing 6-second spirometry results with post-BD diagnostic spirometry (95% confidence interval, 0.27–0.41, mean difference +3.7%, see Figure 3). The Bland–Altman plot showed that extreme differences in FEV1/FEV6 between the two devices (more than twice the s.d.) were frequent (Figure 3). In addition, the pocket spirometer produced lower values for this ratio at values of 90% and higher. This latter finding was also observed in a laboratory linearity check comparing COPD-6 measurements with a flow-volume calibrator (Flow-Volume Calibrator; Jones Medical Instruments, Oak Brook, IL, USA).

Bottom Line: Underdiagnosis of chronic obstructive pulmonary disease (COPD) in primary care can be improved by a more efficient screening strategy.We analysed two related Mexico City cross-sectional samples.A three-step screening strategy for COPD substantially reduces the need for spirometry testing when only a COPD scale is used for screening.

View Article: PubMed Central - PubMed

Affiliation: Department of Epidemiology, National Institute of Respiratory Diseases, Mexico City, Mexico.

ABSTRACT

Background: Underdiagnosis of chronic obstructive pulmonary disease (COPD) in primary care can be improved by a more efficient screening strategy.

Aims: To evaluate a three-step method of screening for COPD consisting of an initial short questionnaire followed by measurement of forced expiratory volume in 1s/forced expiratory volume in 6s (FEV1/FEV6) using an inexpensive pocket spirometer in those with high risk, and diagnostic quality spirometry in those with a low FEV1/FEV6.

Methods: We analysed two related Mexico City cross-sectional samples. The 2003 Mexico City PLATINO survey (n=542) was used to develop a short questionnaire to determine the risk of COPD and a 2010 survey (n=737) additionally used a pocket spirometer. The discriminatory power of the two instruments was assessed with receiver operator characteristic (ROC) curves using three COPD definitions.

Results: The developed COPD scale included two variables from a simple questionnaire and, in ROC analysis, an area under the curve (AUC) between 0.64 and 0.77 was found to detect COPD. The pocket spirometer had an AUC between 0.85 and 0.88 to detect COPD. Using the COPD scale as a first screening step excluded 35-48% of the total population from further testing at the cost of not detecting 8-18% of those with COPD. Using the pocket spirometer and sending those with a FEV1/FEV6<0.80 for diagnostic quality spirometry is very efficient, and substantially improved the positive predictive value at the cost of not detecting one-third of COPD cases.

Conclusions: A three-step screening strategy for COPD substantially reduces the need for spirometry testing when only a COPD scale is used for screening.

Show MeSH
Related in: MedlinePlus