CT whole lung radiomic nomogram: a potential biomarker for lung function evaluation and identification of COPD

Table 1 Baseline characteristics of the study population

Characteristic	Training cohort (n = 1200)			Internal validation cohort (n = 514)			External validation cohort (n = 1071)
Characteristic	Non-COPD (n = 491)	COPD (n = 709)	P-value	Non-COPD (n = 218)	COPD (n = 296)	P-value	Non-COPD (n = 668)	COPD (n = 403)	P-value
Age (years, mean ± SD)	63.9 ± 0.5	70.0 ± 0.4	< 0.001	64.1 ± 0.7	69.2 ± 0.6	< 0.001	58.9 ± 0.5	67.5 ± 0.5	< 0.001
Sex [n (%)]			< 0.001			< 0.001			< 0.001
Male	232 (47.3)	509 (71.8)		104 (47.7)	214 (72.3)		326 (48.8)	330 (81.9)
Female	259 (52.7)	200 (28.2)		114 (52.3)	82 (27.7)		342 (51.2)	73 (18.1)
Height (cm, mean ± SD)	160.9 ± 0.5	163.9 ± 0.3	< 0.001	160.9 ± 0.6	163.9 ± 0.5	< 0.001	161.2 ± 0.3	163.3 ± 0.4	< 0.001
Weight (kg, mean ± SD)	63.7 ± 0.5	65.4 ± 0.4	0.003	63.5 ± 0.8	64.6 ± 0.7	0.270	62.4 ± 0.4	63.6 ± 0.6	0.132
BMI (kg/m², mean ± SD)	25.3 ± 0.6	24.3 ± 0.2	0.462	24.5 ± 0.3	24.0 ± 0.2	0.153	24.0 ± 0.1	23.8 ± 0.2	0.251
Smoking status [n (%)]			< 0.001			< 0.001			< 0.001
Non-smoker	397 (80.9)	416 (58.7)		176 (80.7)	183 (61.8)		527 (78.9)	207 (51.4)
Former smoker	13 (2.6)^a	90 (12.7)^a		10 (4.6)^a	35 (11.8)^a		44 (6.6)^a	88 (21.8)^a
Current smoker	81 (16.5)^a,b	203 (28.6)^a,b		32 (14.7)^a	78 (26.4)^a		97 (14.5)^a,b	108 (26.8)^a,b

^aP < 0.05 vs. non-smoker, ^bP < 0.05 vs. former smoker. COPD chronic obstructive pulmonary disease, BMI body mass index, SD standard deviation

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