Computed Tomography Phenotypes in Severe, Early-Onset Chronic Obstructive Pulmonary Disease

Figures & data

Figure 1 Computed tomography (CT) scans from two participants in the Boston Early-Onset COPD Study, demonstrating the disconnect between emphysema severity on CT scans and lung function testing in patients with COPD. Subject A has severe emphysema yet higher lung function (emphysema severity score = 21.7; FEV₁ = 38% predicted) than Subject B, who has minimal emphysema and lower lung function (emphysema severity score = 4.0; FEV₁ = 20% predicted). The mosaic attenuation in Subject B is consistent with airways disease as a cause for the severe airflow obstruction.

Table 1 Emphysema severity scale

Scores were assigned for the upper, mid, and lower portions (see Methods for definitions) of the right and left lung (11). Scores across the six lung regions were totaled for a maximum possible score of 24.

0. Normal (none)

0.5. Trivial (< 5% of lung affected)

1. Mild (5–25%)

2. Moderate (26–50%)

3. Marked (51–75%)

4. Severe (> 75%)

Figure 2 Distribution of computed tomography emphysema severity scores in the Boston Early-Onset COPD Study.

Table 2 Differences between emphysema-predominant (N = 66) and airway-predominant (N = 22) probands in the Boston Early-Onset COPD Study

	Emphysema-predominant	Airway-predominant
Characteristic	Mean (SD) or N (%)	Mean (SD) or N (%)	p-value	p-value (adjusted)
Age, years	48.2 (4.5)	47.8 (4.3)	NS	–
Female sex	47 (71.2%)	17 (77.3%)	NS	–
Pack-years of smoking	39.2 (20.8)	29.5 (17.0)	0.05	0.07
FEV1 % predicted, pre-bronchodilator	17.4 (6.9)	22.4 (6.9)	0.004	0.009
FEV1 % predicted, post-bronchodilator^†	19.1 (7.5)	26.3 (8.4)	0.0004	0.001
FEV1/FVC, pre-bronchodilator	0.31 (0.12)	0.33 (0.07)	NS	NS
FEV1/FVC, post-bronchodilator^†	0.29 (0.11)	0.33 (0.08)	NS	NS
Chronic bronchitis	25 (37.9%)	9 (40.9%)	NS	NS
Episodes of increased cough and phlegm^‡	32 (48.5%)	12 (54.6%)	NS	NS
Frequent exacerbations^§	43 (65.2%)	17 (77.3%)	NS	NS

p-values < 0.1 are shown.

* p-values for age and sex are unadjusted. p-value for pack-years is adjusted for age and sex. All other p-values are adjusted for age, sex, and pack-years of smoking.

^†Emphysema predominant: N = 60; Airway-predominant: N = 21.

^‡Episodes of increased cough and phlegm lasting 3 weeks or more.

^§ Three or more exacerbations within the 3 years prior to enrollment.

Table 3 Asthma-related phenotypes in emphysema-predominant (N = 66) and airway-predominant (N = 22) probands in the Boston Early-Onset COPD Study.

	Emphysema-predominant	Airway-predominant
Characteristic	Mean (SD) or N (%)	Mean (SD) or N (%)	p-value	p-value (adjusted)
BDR (ml)^†	68 (81)	110 (87)	0.05	0.03
BDR (% predicted)^†	2.2 (2.5)	3.7 (2.7)	0.03	0.02
BDR (ATS definition)^‡	4 (6.7%)	6 (28.6%)	0.02	0.009
Log10 IgE level^§	1.28 (0.58)	1.64 (0.54)	0.08	0.09
Attacks of wheezing	42 (63.6%)	17 (77.3%)	NS	NS
Physician diagnosed asthma	33 (50.0%)	16 (72.7%)	0.06	0.04

ATS = American Thoracic Society; BDR = Bronchodilator Response; IgE = Immunoglobulin E.

p-values < 0.1 are shown.

* Adjusted for age, sex, and pack-years of smoking.

^† Emphysema predominant: N = 60; Airway-predominant: N = 21.

^‡ Change in FEV₁ of at least 200 ml and at least 12% of baseline.

^§ Emphysema predominant: N = 36; Airway-predominant: N = 10.