Sex differences of COPD phenotypes in nonsmoking patients

Figures & data

Figure 1 Selection of study patients from the initial Korean cohort.

Abbreviations: FEV₁, forced expiratory volume in 1 second; FVC, forced vital capacity.

Table 1 Baseline characteristics of nonsmoking females and males with COPD

Variables	Females (n=62)	Males (n=35)	P-value
Age, years	74±7.2	71±7.2	0.04
BMI, kg/m^2	23.5±2.9	25±3	0.015
MMRC dyspnea scale (0/1/2/3/4)	9/24/6/17/6	6/16/6/2/5	0.13
CAT	19.4±10	18±10.8	0.51
History of respiratory disease (n, %)	32 (51.6)	24 (68.6)	0.10
History of tuberculosis (n, %)	13 (22.4)	5 (14.3)	0.34
History of asthma (n, %)	15 (26.8)	8 (22.8)	0.67
History of biomass exposure (n, %)	33 (53.2)	5 (14.3)	<0.01
History of exacerbation (n, %)	6 (9.7)	2 (5.7)	0.50
FEV1/FVC (median, IQR)	61.8 (55–65.7)	62.3 (54.7–66.8)	0.94
FVC (% of predicted)	104.3±21.1	96.8±18.5	0.084
FEV1 (% of predicted)	84.9±21.2	80.3±17.8	0.29
Mean wall area (%)	71.8±5.1	69.4±5.3	0.027
Emphysema index (median, IQR)	1.7 (0.7–4.9)	4.2 (1.3–10.4)	<0.01
Mean lung density ratio	0.94±0.05	0.94±0.03	0.91

Notes: Results are reported as mean ± standard deviation or as median and IQR and compared by independent sample t-tests and Mann–Whitney U-tests, respectively. Emphysema index = volume fraction (%) of the lung below −950 HU, wall area (%) = wall area/(wall area + lumen area) ×100, and mean lung density ratio = mean lung density ratio of full expiration and inspiration.

Abbreviations: BMI, body mass index; CAT, COPD assessment test; FEV₁, forced expiratory volume in 1 second; FVC, forced vital capacity; IQR, interquartile range; MMRC, Modified Medical Research Council.

Table 2 Multivariate analysis of factors associated with sex differences in CT measurements of changes in lung structure in nonsmoking patients with COPD

CT measurements	Females (n=62)	Males (n=35)	P-value
Mean wall area (%)	71.8±5.1	69.4±5.3	0.013
Emphysema index	3.5±4.2	6.2±5.7	<0.01
MLD ratio	0.94±0.05	0.94±0.03	0.85

Notes: Data are presented as mean ± standard deviation, after adjusting for age, body mass index, lung function, and history of biomass exposure. Emphysema index = volume fraction (%) of the lung below −950 HU, wall area (%) = wall area/(wall area + lumen area) ×100, and mean lung density ratio = mean lung density ratio of full expiration and inspiration.

Abbreviations: CT, computed tomography; MLD, mean lung density.

Figure 2 Representative cases showing sex differences on computed tomography (CT) image.

Notes: (A) CT image of 73-year old male having no history of cigarette smoking showing diffuse emphysema. (B) CT image of 81-year old female having no history of cigarette smoking showing diffuse bronchial wall thickening and no visual emphysema.

Table 3 Subgroup analysis of emphysema index in nonsmoking males and females with COPD with and without a history of biomass exposure

CT measurements	Females	Males	P-value
Emphysema index (median, IQR)
With biomass exposure	2.3 (0.8–4.8)	5.9 (3.5–10.1)	0.052
Without biomass exposure	1.5 (0.4–4.9)	3.8 (1.3–10.4)	0.056

Notes: Data are presented as median with IQRs. Emphysema index = volume fraction (%) of the lung below −950 HU.

Abbreviations: IQR, interquartile range; CT, computed tomography.

Table 4 Subgroup analysis of the extent of airway disease in nonsmoking males and females with COPD with and without a history of biomass exposure

CT measurements	Females	Males	P-value
Mean wall area (%)
With biomass exposure	72.2±5.6	65±4.8	0.02
Without biomass exposure	71.4±4.5	70.1±5	0.18

Notes: Data are presented as mean ± standard deviation, after adjusting for age, body mass index, lung function, and history of biomass exposure. Wall area (%) = wall area/(wall area + lumen area) ×100.

Abbreviation: CT, computed tomography.