Material and Method: A retrospective case-controlled study was conducted at the chest clinic, Maharaj Nakorn Chiang Mai Hospital from 1st August 2009 to 31st July 2010. The clinical relevant data for acute exacerbation (age, sex, co-morbidity, severity of COPD, COPD medication, annual influenza vaccination, compliance with inhaled drug use, chest radiographic abnormality, and long-term oxygen therapy) were compared between severe AECOPD and stable COPD patients by logistic regression analysis.

Results: Out of 137 COPD patients, 17 (12.4%) had severe AECOPD with 29 episodes (21.2%). Six risk factors were identified, two modifiable and four non-modifiable. The two modifiable risk factors were annual influenza non-vaccination (odds ratio [OR] 27.79; 95% confidence interval [CI], 2.29-337.66, p-value = 0.01) and improper use of inhaled devices (OR 9.94, 95%CI 1.07-92.54, p-value = 0.04). The four non-modifiable risk factors were age <60 yrs (OR, 10.67; 95%CI, 1.92-59.31, p-value = 0.01), hypertension (OR, 4.03; 95%CI. 1.05-15.44, p-value = 0.04), enlarged pulmonary trunk as demonstrated by chest radiograph (OR, 8.61; 95%CI, 1.49-49.85, p-value = 0.02), and long-term oxygen therapy (OR, 7.09; 95%CI, 1.36-37.00, p-value = 0.02).

Conclusion: Six risk factors of severe AECOPD among patients whom were provided regularly managed by pulmonologists were identified; two of them, annual influenza non-vaccination and improper use of inhaled devices, could be potentially modified.

Keywords: Risk factor, Chronic obstructive pulmonary disease, Exacerbation