Factors associated with exacerbation in mild- to-moderate COPD patients

Figures & data

Table 1 Baseline characteristics of included patients with COPD and mild-to-moderate airflow limitation

Characteristics	Total (n=570)
Age (years), mean (SD)	69.8 (7.8)
Male, no (%)	515 (90.4)
Follow-up duration (months), mean (SD)	22.3 (21.4)
Lung function, mean (SD)
Postbronchodilator FEV1 (L)	1.79 (0.54)
Postbronchodilator FEV1 (% of predicted)	66.0 (11.6)
Postbronchodilator FVC (L)	3.28 (0.75)
Postbronchodilator FVC (% of predicted)	87.4 (15.4)
Smoking amount (pack-years), mean (SD)	43.8 (24.3)
Total CAT score, mean (SD)	13.9 (6.9)
mMRC score, mean (SD)	1.36 (0.85)
SGRQ-c, mean (SD)	30.4 (6.5)
Number of patients with previous exacerbation history, no (%)	114 (20)
Comorbidities, no (%)
Hypertension	37.9
Diabetes mellitus	14.3
Gastroesophageal reflux disease	10.4
Hyperlipidemia	8.3
Osteoporosis	3.8
Congestive heart failure	3.1
Past medical history, no (%)
Asthma	65.4
Tuberculosis	22.1
Measles	17.4
Pneumonia	14.2
Allergic rhinitis	11.0

Abbreviations: CAT, COPD assessment test; FEV₁, forced expiratory volume in 1 second; FVC, forced vital capacity; mMRC, modified Medical Research Council; SD, standard deviation; SGRQ-c, St George’s Respiratory Questionnaire for COPD.

Figure 1 Exacerbation rate of COPD according to the GOLD classification and severity of airflow limitation during the first year of follow-up.

Abbreviations: FEV₁, forced expiratory volume in 1 second; GOLD, Global Initiative for Chronic Obstructive Lung Disease.

Table 2 Comparison of baseline characteristics between patients with experience of COPD exacerbation and those without

Variables	Experience of acute exacerbation	Non-experience of acute exacerbation	P-value
Age (years)	70.4±6.9	70.4±7.7	0.989
BMI (kg/m^2)	23.6±2.9	23.4±3.5	0.732
mMRC score	1.57±0.93	1.25±0.85	0.015
SGRQ-c score	37.9±2.00	28.1±1.6	0.000
CAT score	16.41±7.80	13.25±6.83	0.005
Postbronchodilator FEV1 (L)	1.69±0.44	1.80±0.48	0.102
Postbronchodilator FEV1 (% of predicted)	64.5±13.8	67.1±13.0	0.188

Notes: Data shown as mean ± standard deviation. An independent t-test was used to compare the two groups.

Abbreviations: BMI, body mass index; CAT, COPD assessment test; FEV₁, forced expiratory volume in 1 second; mMRC, modified Medical Research Council; SGRQ-c, St George’s Respiratory Questionnaire for COPD.

Table 3 Comparison of self-reported comorbidities and past medical histories between patients with a history of COPD exacerbation and those without

Variables	Presence of acute exacerbation	Absence of acute exacerbation	P-value
Comorbidities (%)
Hypertension	40.6	39.9	0.203
Diabetes mellitus	12.5	12.5	0.453
Congestive heart failure	3.1	4.9	0.392
Osteoporosis	3.1	2.8	0.249
Gastroesophageal reflux disease	7.8	11.9	0.419
Hyperlipidemia	5.7	3.1	0.018
Past medical history (%)
Asthma	62.9	71.6	0.143
Allergic rhinitis	27.4	10.8	0.008
Pneumonia	23.0	14.9	0.008
Measles	21.0	18.9	0.475
Tuberculosis	19.4	22.3	0.110

Note: A chi-square test was used to compare the two groups.

Table 4 Logistic regression model for the risk factors for COPD exacerbation

Variable	OR (95% CI)	P-value
Previous exacerbation history	3.12 (1.35–7.23)	0.008
History of pneumonia	1.85 (1.06–3.25)	0.032
SGRQ-c score	1.02 (1.00–1.04)	0.034
Allergic rhinitis	1.15 (0.61–2.19)	0.667
mMRC	1.07 (0.66–1.75)	0.777
CAT score	1.00 (0.93–1.07)	0.883
Hyperlipidemia	0.82 (0.52–1.30)	0.384

Abbreviations: CAT, COPD assessment test; CI, confidence interval; mMRC, modified Medical Research Council; OR, odds ratio; SGRQ-c, St George’s Respiratory Questionnaire for COPD.

Figure S1 Proportion of patients according to the exacerbation of COPD during the first year of follow-up.

Abbreviation: GOLD, Global Initiative for Chronic Obstructive Lung Disease.