Risk stratification for COPD diagnosis through an active search strategy in primary care

Figures & data

Table 1 Demographic and clinical characteristics of the whole population by COPD diagnosis

Characteristic	Total N=1,725	COPD N=793	Non-COPD N=932	P-value
Sex (male), n (%)	1,231 (71.4)	587 (74.1)	644 (69.1)	0.0554
Age (years), mean (SD)	60.1 (10.2)	61.3 (10.0)	59.1 (10.3)	<0.0001
BMI (kg/m^2), mean (SD)	27.5 (4.1)	27.4 (4.1)	27.6 (4.2)	0.66
Smoking habit, n (%)
Current smoker	1,003 (58.1)	463 (58.4)	540 (57.9)	0.78
Former smoker	722 (41.9)	330 (41.6)	392 (42.0)
Total smoking time (years), mean (SD)	33.1 (10.4)	34.0 (10.4)	32.3 (10.4)	0.0011
History of low respiratory infections, n (%)	941 (54.6)	489 (61.7)	452 (48.5)	<0.0001
Comorbidities (yes), n (%)	1,240 (71.9)	609 (76.8)	631 (67.7)	<0.0001
Symptoms, n (%)
Chronic cough	1,293 (75.0)	639 (80.6)	654 (70.2)	<0.0001
Chronic sputum	1,080 (62.6)	525 (66.2)	555 (59.6)	0.0064
Complications in the last year, n (%)
Acute bronchitis	969 (56.2)	486 (61.3)	483 (51.8)	0.0001
Acute bronchitis + hospitalization	211 (12.2)	118 (14.9)	93 (10.0)	0.0037

Abbreviations: BMI, body mass index; SD, standard deviation.

Figure 1 Patient disposition.

Note: *Some patients had more than one case of ineligibility.
Abbreviation: CAT, COPD Assessment Test.

Table 2 Lung function and quality of life of the whole population by COPD diagnosis

Variable	Total N=1,725	COPD N=793	Non-COPD N=932	P-value
FEV1 post-bronchodilator, mean (SD)	2,238.1 (943.1)
% FEV1 (of reference), mean (SD)	73.6 (21.1)
Clinical judgment, n (%)
Patient has COPD	1,393 (80.8)	725 (91.4)	668 (71.7)	<0.0001
Patient does not have COPD	311 (18.0)	61 (7.7)	250 (26.8)
Dyspnea by mMRC scale, n (%)
0	293 (17.0)	84 (10.6)	209 (22.4)	<0.0001
1	846 (49.0)	390 (49.2)	456 (48.9)
2	385 (22.3)	227 (28.6)	158 (17.0)
3	105 (6.1)	63 (7.9)	42 (4.5)
4	10 (0.6)	4 (0.5)	6 (0.6)
Severity of obstruction, n (%)
GOLD 1: FEV1 ≥80%		147 (18.5)
GOLD 2: 50%≤ FEV1 <80%		472 (59.5)
GOLD 3: 30%≤ FEV1 <50%		140 (17.7)
GOLD 4: FEV1 <30%		34 (4.3)
CAT score, mean (SD)	16.3 (7.7)	18.1 (7.5)	14.8 (7.5)	<0.0001

Abbreviations: FEV₁, forced expiratory volume in 1 second; SD, standard deviation; mMRC, modified Medical Research Council; GOLD, Global Initiative for Chronic Obstructive Lung Disease; CAT, COPD Assessment Test.

Table 3 Logistic regression analysis (predictive model)

Model	P-value	OR	95% CI
Previous lower respiratory tract infections (yes/no)	0.0011	1.40	1.14–1.71
Dyspnea (yes/no)	<0.0001	2.29	1.77–2.96
Chronic cough (yes/no)	0.0046	1.41	1.11–1.79
AUC =0.6121
Sensitivity =48.41
Specificity =66.04
False-positive rate =44.62
False-negative rate =40.48
Positive predictive value =0.55
Negative predictive value =0.60

Abbreviations: OR, odds ratio; CI, confidence interval; AUC, area under the curve.

Figure 2 ROC curve of the best model (model with respiratory infections, dyspnea, and chronic cough).

Abbreviation: ROC, receiver operating characteristic.