Risk of acute exacerbation and severe acute exacerbation associated with different severities of COPD at diagnosis

Abstract

Background: COPD is the most common respiratory disease worldwide and also is a major cause of morbidity and mortality throughout the world which imposes important challenge to public health. Despite increasing societal burden of COPD, it is widely under-recognised and under-diagnosed by both the patients and physicians due to various reasons including the low usage of pulmonary function tests(PFTs). However recent studies suggest that the decline of lung function in COPD patients occur in the earlier course of the disease than previously thought, which suggest implementation of aggressive testing to avoid delay in diagnosis and respective initiation of treatments. This study aims to assess the difference in health outcomes, specifically acute exacerbation and severe acute exacerbation between the patients diagnosed at varying severities of COPD.

Methods: This prospective cohort study used the National Health Insurance Service-National Sample Cohort(NHIS-NSC) to enroll newly diagnosed COPD patients with varying disease severities of mild, moderate and severe COPD between 2006 and 2007, then the patients were followed up for events of acute exacerbation and severe acute exacerbation until 31st December 2013.

Results: Total of 1,280 patients which consisted of 685 of patients diagnosed as mild COPD, 383 of patients diagnosed as moderate COPD, 212 of patients diagnosed as severe COPD. When compared to patients diagnosed as mild COPD, the risk of acute exacerbation was higher for patients diagnosed as moderate COPD (unadjusted HR: 1.13, 95% CI: 0.70-1.82

adjusted HR: 1.07, 95% CI: 0.72-1.59) and more dramatically with patients diagnosed as severe COPD (unadjusted HR: 2.45, 95% CI: 1.54-3.88

adjusted HR: 2.12, 95% CI: 1.43-3.14). The risk of severe acute exacerbation was also higher for patients diagnosed as moderate COPD (unadjusted HR: 1.45, 95% CI: 0.99-2.13

adjusted HR: 1.36, 95% CI: 0.94-1.96) and for patients diagnosed as severe COPD (unadjusted HR: 2.94, 95% CI: 2.02-4.29

adjusted HR: 2.56, 95% CI: 1.77-3.71) when compared to the patients diagnosed as mild COPD.

Conclusions: The risk of acute exacerbation and severe acute exacerbation was increased in patients diagnosed as moderate COPD and more dramatically with patients diagnosed as severe COPD when compared to patients with mild COPD at diagnosis, which may contribute as an evidence to enhancing importance of early diagnosis in COPD.