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Cross-sectional analysis of the utility of pulmonary function tests in predicting emphysema in ever-smokers.

Hesselbacher SE, Ross R, Schabath MB, Smith EO, Perusich S, Barrow N, Smithwick P, Mammen MJ, Coxson H, Krowchuk N, Corry DB, Kheradmand F - Int J Environ Res Public Health (2011)

Bottom Line: We enrolled 224 ever-smokers (current or former) over the age of 40.Standardized airway wall thickness was increased in subjects with airflow obstruction, but did not correlate with emphysema severity.Airway wall thickness quantified by CT morphometry was associated with airflow limitation, but not with emphysema indicating that the heterogeneous nature of lung disease in smokers may represent distinct phenotypes.

View Article: PubMed Central - PubMed

Affiliation: Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA. hesselba@bcm.tmc.edu

ABSTRACT
Emphysema is largely an under-diagnosed medical condition that can exist in smokers in the absence of airway obstruction. We aimed to determine the sensitivity and specificity of pulmonary function tests (PFTs) in assessing emphysema using quantitative CT scans as the reference standard. We enrolled 224 ever-smokers (current or former) over the age of 40. CT of thorax was used to quantify the low attenuation area (% emphysema), and to measure the standardized airway wall thickness. PFTs were used individually and in combination to predict their ability to discriminate radiographic emphysema. Significant emphysema (>7%) was detected in 122 (54%) subjects. Twenty six (21%) emphysema subjects had no evidence of airflow obstruction (FEV(1)/FVC ratio <70%), while all subjects with >23% emphysema showed airflow obstruction. The sensitivity and specificity of spirometry for detecting radiographic emphysema were 79% and 75%, respectively. Standardized airway wall thickness was increased in subjects with airflow obstruction, but did not correlate with emphysema severity. In this cohort of lifetime ever-smokers, PFTs alone were inadequate for diagnosing emphysema. Airway wall thickness quantified by CT morphometry was associated with airflow limitation, but not with emphysema indicating that the heterogeneous nature of lung disease in smokers may represent distinct phenotypes.

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Related in: MedlinePlus

Schematic overview of the study design and FEV1% predicted and FEV1/FVC ratio among ever-smokers. (A) Flowchart of the recruitment, exclusions, dropouts, measurements, and results in evaluating the diagnostic accuracy of spirometry (FEV1/FVC < 70%) in the detection of emphysema, as defined by CT quantification (Low Attenuation Area; LAA ≥ 7%) is shown. The number of participants recruited, excluded, and measured is shown within the respective boxes. # Four subjects were excluded (three for concomitant lung disease; one for α-1-antitrypsin deficiency). ¶ Six total subjects did not have CT performed (two expired; three lost to follow-up; one withdrew consent). (B) FEV1% predicted was plotted by age group among current (N = 133, solid circles) and former (N = 91, open circles) smokers. (C) FEV1/FVC ratio was plotted by age group among current (N = 133, solid circles) and former (N = 91, closed circles) smokers. The group means are depicted by solid (current smokers) and dashed (former smokers) lines. * P < 0.05 current smokers versus former smokers.
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f1-ijerph-08-01324: Schematic overview of the study design and FEV1% predicted and FEV1/FVC ratio among ever-smokers. (A) Flowchart of the recruitment, exclusions, dropouts, measurements, and results in evaluating the diagnostic accuracy of spirometry (FEV1/FVC < 70%) in the detection of emphysema, as defined by CT quantification (Low Attenuation Area; LAA ≥ 7%) is shown. The number of participants recruited, excluded, and measured is shown within the respective boxes. # Four subjects were excluded (three for concomitant lung disease; one for α-1-antitrypsin deficiency). ¶ Six total subjects did not have CT performed (two expired; three lost to follow-up; one withdrew consent). (B) FEV1% predicted was plotted by age group among current (N = 133, solid circles) and former (N = 91, open circles) smokers. (C) FEV1/FVC ratio was plotted by age group among current (N = 133, solid circles) and former (N = 91, closed circles) smokers. The group means are depicted by solid (current smokers) and dashed (former smokers) lines. * P < 0.05 current smokers versus former smokers.

Mentions: In all, 235 ever smokers were enrolled, of which five were excluded or withdrew consent. Six subjects performed PFT, but failed to obtain CT scan, therefore the analyses included data collected from 224 subjects that completed both PFT and CT (Figure 1A). The clinical and demographic characteristics of study subjects, categorized by GOLD criteria, are shown in Table 1.


Cross-sectional analysis of the utility of pulmonary function tests in predicting emphysema in ever-smokers.

Hesselbacher SE, Ross R, Schabath MB, Smith EO, Perusich S, Barrow N, Smithwick P, Mammen MJ, Coxson H, Krowchuk N, Corry DB, Kheradmand F - Int J Environ Res Public Health (2011)

Schematic overview of the study design and FEV1% predicted and FEV1/FVC ratio among ever-smokers. (A) Flowchart of the recruitment, exclusions, dropouts, measurements, and results in evaluating the diagnostic accuracy of spirometry (FEV1/FVC < 70%) in the detection of emphysema, as defined by CT quantification (Low Attenuation Area; LAA ≥ 7%) is shown. The number of participants recruited, excluded, and measured is shown within the respective boxes. # Four subjects were excluded (three for concomitant lung disease; one for α-1-antitrypsin deficiency). ¶ Six total subjects did not have CT performed (two expired; three lost to follow-up; one withdrew consent). (B) FEV1% predicted was plotted by age group among current (N = 133, solid circles) and former (N = 91, open circles) smokers. (C) FEV1/FVC ratio was plotted by age group among current (N = 133, solid circles) and former (N = 91, closed circles) smokers. The group means are depicted by solid (current smokers) and dashed (former smokers) lines. * P < 0.05 current smokers versus former smokers.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC3108112&req=5

f1-ijerph-08-01324: Schematic overview of the study design and FEV1% predicted and FEV1/FVC ratio among ever-smokers. (A) Flowchart of the recruitment, exclusions, dropouts, measurements, and results in evaluating the diagnostic accuracy of spirometry (FEV1/FVC < 70%) in the detection of emphysema, as defined by CT quantification (Low Attenuation Area; LAA ≥ 7%) is shown. The number of participants recruited, excluded, and measured is shown within the respective boxes. # Four subjects were excluded (three for concomitant lung disease; one for α-1-antitrypsin deficiency). ¶ Six total subjects did not have CT performed (two expired; three lost to follow-up; one withdrew consent). (B) FEV1% predicted was plotted by age group among current (N = 133, solid circles) and former (N = 91, open circles) smokers. (C) FEV1/FVC ratio was plotted by age group among current (N = 133, solid circles) and former (N = 91, closed circles) smokers. The group means are depicted by solid (current smokers) and dashed (former smokers) lines. * P < 0.05 current smokers versus former smokers.
Mentions: In all, 235 ever smokers were enrolled, of which five were excluded or withdrew consent. Six subjects performed PFT, but failed to obtain CT scan, therefore the analyses included data collected from 224 subjects that completed both PFT and CT (Figure 1A). The clinical and demographic characteristics of study subjects, categorized by GOLD criteria, are shown in Table 1.

Bottom Line: We enrolled 224 ever-smokers (current or former) over the age of 40.Standardized airway wall thickness was increased in subjects with airflow obstruction, but did not correlate with emphysema severity.Airway wall thickness quantified by CT morphometry was associated with airflow limitation, but not with emphysema indicating that the heterogeneous nature of lung disease in smokers may represent distinct phenotypes.

View Article: PubMed Central - PubMed

Affiliation: Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA. hesselba@bcm.tmc.edu

ABSTRACT
Emphysema is largely an under-diagnosed medical condition that can exist in smokers in the absence of airway obstruction. We aimed to determine the sensitivity and specificity of pulmonary function tests (PFTs) in assessing emphysema using quantitative CT scans as the reference standard. We enrolled 224 ever-smokers (current or former) over the age of 40. CT of thorax was used to quantify the low attenuation area (% emphysema), and to measure the standardized airway wall thickness. PFTs were used individually and in combination to predict their ability to discriminate radiographic emphysema. Significant emphysema (>7%) was detected in 122 (54%) subjects. Twenty six (21%) emphysema subjects had no evidence of airflow obstruction (FEV(1)/FVC ratio <70%), while all subjects with >23% emphysema showed airflow obstruction. The sensitivity and specificity of spirometry for detecting radiographic emphysema were 79% and 75%, respectively. Standardized airway wall thickness was increased in subjects with airflow obstruction, but did not correlate with emphysema severity. In this cohort of lifetime ever-smokers, PFTs alone were inadequate for diagnosing emphysema. Airway wall thickness quantified by CT morphometry was associated with airflow limitation, but not with emphysema indicating that the heterogeneous nature of lung disease in smokers may represent distinct phenotypes.

Show MeSH
Related in: MedlinePlus