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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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Correlation between PFTs and % emphysema in ever-smokers. Representative quantitative CT images of lung (left images) are matched to conventional CT images of the same lung (right images) from individuals without (A) and with (B) emphysema. Yellow background within lung margins (left images) was quantified as a percent of whole lung to determine the percent emphysema (1% and 40%, respectively; see Methods). (C) FEV1/FVC ratio was plotted against % emphysema, with regression lines in current (N = 133; solid line) and former (N = 91; dashed line) smokers. P < 0.0001; r = −0.7136 and r = −0.7574 Goodness of Fit for current and former smokers respectively. The lines are similar in slope (P = 0.78) and elevation (P = 0.17). The graph is divided into quadrants based on cutoff values for FEV1/FVC (70%) and % emphysema (7%). Additional dashed lines identify FEV1/FVC 78% (horizontal) and 23% emphysema (vertical). (D) DLCO% predicted plotted against % emphysema with regression lines in current (N =126; solid line) and former (N =89; dotted line) smokers. P < 0.0001; r = −0.4690 and r = −0.7074 Goodness of Fit for current and former smokers respectively. The lines are significantly different in elevation (p = 0.0003) but not slope (P = 0.79). The graph is separated into quadrants based on cutoffs for DLCO% (75%) and % emphysema (7%).
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f3-ijerph-08-01324: Correlation between PFTs and % emphysema in ever-smokers. Representative quantitative CT images of lung (left images) are matched to conventional CT images of the same lung (right images) from individuals without (A) and with (B) emphysema. Yellow background within lung margins (left images) was quantified as a percent of whole lung to determine the percent emphysema (1% and 40%, respectively; see Methods). (C) FEV1/FVC ratio was plotted against % emphysema, with regression lines in current (N = 133; solid line) and former (N = 91; dashed line) smokers. P < 0.0001; r = −0.7136 and r = −0.7574 Goodness of Fit for current and former smokers respectively. The lines are similar in slope (P = 0.78) and elevation (P = 0.17). The graph is divided into quadrants based on cutoff values for FEV1/FVC (70%) and % emphysema (7%). Additional dashed lines identify FEV1/FVC 78% (horizontal) and 23% emphysema (vertical). (D) DLCO% predicted plotted against % emphysema with regression lines in current (N =126; solid line) and former (N =89; dotted line) smokers. P < 0.0001; r = −0.4690 and r = −0.7074 Goodness of Fit for current and former smokers respectively. The lines are significantly different in elevation (p = 0.0003) but not slope (P = 0.79). The graph is separated into quadrants based on cutoffs for DLCO% (75%) and % emphysema (7%).

Mentions: We found a significant negative correlation between the severity of emphysema, as quantified by CT morphometry (%LAA, representative samples are shown in [Figures 3(A,B)]) with FEV1/FVC (Figure 3C), and DLCO% predicted (Figure 3D). The negative correlation between % emphysema and FEV1/FVC was virtually identical in current and former smokers but there was a significant difference in the Y intercept of the correlation line in current when compared to former smokers.


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)

Correlation between PFTs and % emphysema in ever-smokers. Representative quantitative CT images of lung (left images) are matched to conventional CT images of the same lung (right images) from individuals without (A) and with (B) emphysema. Yellow background within lung margins (left images) was quantified as a percent of whole lung to determine the percent emphysema (1% and 40%, respectively; see Methods). (C) FEV1/FVC ratio was plotted against % emphysema, with regression lines in current (N = 133; solid line) and former (N = 91; dashed line) smokers. P < 0.0001; r = −0.7136 and r = −0.7574 Goodness of Fit for current and former smokers respectively. The lines are similar in slope (P = 0.78) and elevation (P = 0.17). The graph is divided into quadrants based on cutoff values for FEV1/FVC (70%) and % emphysema (7%). Additional dashed lines identify FEV1/FVC 78% (horizontal) and 23% emphysema (vertical). (D) DLCO% predicted plotted against % emphysema with regression lines in current (N =126; solid line) and former (N =89; dotted line) smokers. P < 0.0001; r = −0.4690 and r = −0.7074 Goodness of Fit for current and former smokers respectively. The lines are significantly different in elevation (p = 0.0003) but not slope (P = 0.79). The graph is separated into quadrants based on cutoffs for DLCO% (75%) and % emphysema (7%).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f3-ijerph-08-01324: Correlation between PFTs and % emphysema in ever-smokers. Representative quantitative CT images of lung (left images) are matched to conventional CT images of the same lung (right images) from individuals without (A) and with (B) emphysema. Yellow background within lung margins (left images) was quantified as a percent of whole lung to determine the percent emphysema (1% and 40%, respectively; see Methods). (C) FEV1/FVC ratio was plotted against % emphysema, with regression lines in current (N = 133; solid line) and former (N = 91; dashed line) smokers. P < 0.0001; r = −0.7136 and r = −0.7574 Goodness of Fit for current and former smokers respectively. The lines are similar in slope (P = 0.78) and elevation (P = 0.17). The graph is divided into quadrants based on cutoff values for FEV1/FVC (70%) and % emphysema (7%). Additional dashed lines identify FEV1/FVC 78% (horizontal) and 23% emphysema (vertical). (D) DLCO% predicted plotted against % emphysema with regression lines in current (N =126; solid line) and former (N =89; dotted line) smokers. P < 0.0001; r = −0.4690 and r = −0.7074 Goodness of Fit for current and former smokers respectively. The lines are significantly different in elevation (p = 0.0003) but not slope (P = 0.79). The graph is separated into quadrants based on cutoffs for DLCO% (75%) and % emphysema (7%).
Mentions: We found a significant negative correlation between the severity of emphysema, as quantified by CT morphometry (%LAA, representative samples are shown in [Figures 3(A,B)]) with FEV1/FVC (Figure 3C), and DLCO% predicted (Figure 3D). The negative correlation between % emphysema and FEV1/FVC was virtually identical in current and former smokers but there was a significant difference in the Y intercept of the correlation line in current when compared to former smokers.

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