Patterns and determinants of COPD-related healthcare utilization by severity of airway obstruction in Korea

Abstract

Background: We investigated patients with chronic obstructive pulmonary disease (COPD) to analyze patterns and identify determinants of healthcare use, according to the severity of airflow obstruction. We used retrospective cohort data from a combination of the 4th Korea National Health and Nutritional Examination Survey (KNHANES) and Korean National Health Insurance (NHI) claims.

Methods: Demographic and medical claims data were retrospectively analyzed from the 4th KNHANES along with NHI claims. Eligible patients were aged ≥40 years, who underwent complete pulmonary function tests (PFTs), and had at least one inpatient or outpatient claim coded as COPD between January 1, 2007 and December 31, 2010.

Results: Among 6,663 eligible participants, 897 (13.5%) had airway obstruction. Self-reported physician-diagnosed COPD comprised only 3%, and there were 870 undiagnosed COPD patients (97%). Self-reported physician-diagnosed asthma made up 3.7%. Of the 897 respondents, 244 (27.2%) used COPD-related healthcare services. The frequency of healthcare visits increased with increasing severity of airway obstruction. After a 3-year follow-up period, 646 (74.2% of those initially undiagnosed) remained undiagnosed and only 224 (25.8%) were diagnosed and treated for COPD. Only 27.5% of the 244 participants with airway obstruction who used COPD-related healthcare underwent PFTs during the study period. The percentage of prescribed medications associated with COPD increased in accordance with the severity of the COPD. Inhaled long-acting anticholinergics were prescribed for 10.9% of patients with moderate airway obstruction and for 52.4% of patients with severe obstruction. Inhaled long-acting β-agonists combined with corticosteroids were prescribed for 50% of patients with severe airway obstruction. Conversely, 44.6% of healthcare users were prescribed oral theophylline for COPD treatment, and 21.7% were also prescribed an oral corticosteroid. The determinants of COPD-associated healthcare use in respondents with obstructive lung disease were advanced age, severe airflow limitation, presence of comorbidities, and self-reported physician diagnosis of COPD.

Conclusions: This study ascertained marked underdiagnosed COPD. Although the percentage of prescribed medication used to treat COPD increased with the severity of the COPD, medications primarily prescribed such as oral theophylline or oral corticosteroids are inappropriate for first-line COPD treatment.

Figure 1

Flow chart for selection of study participants. PFT = pulmonary function test; Normal = FEV₁/FVC ≥ 70% and FEV₁ ≥ 80% predicted; Restrictive = FEV₁/FVC ≥ 70% and FEV₁ < 80% predicted; Obstructive = FEV₁/FVC < 70%; Non-user = person who did not use healthcare resources at all with first-listed and secondary diagnosis of COPD; User = person who used any kind of healthcare resource with first-listed and secondary diagnosis of COPD.

Figure 2

Percentage of COPD-related healthcare visits by severity of airway obstruction. Percentages of COPD related healthcare visits in the mild, moderate, and severe airway obstruction cohort are presented on top of each bar of the graph. Total healthcare visits were divided into outpatient clinic visits, inpatient clinic visits, and emergency department visits. a) COPD-related total healthcare visits, b) COPD-related outpatient clinic visits, c) COPD-related inpatient clinic visits, d) COPD-related emergency department visits; mild = FEV₁/FVC < 70% and FEV₁ ≥ 80% predicted; moderate = FEV₁/FVC < 70% and 50 ≤ FEV₁ < 80% predicted; severe = FEV₁/FVC < 70% and FEV₁ < 50% predicted; normal = FEV₁/FVC ≥ 70% and FEV₁ ≥ 80% predicted; restrictive = FEV₁/FVC ≥ 70% and FEV₁ < 80% predicted.

Figure 3

Performance in PFTs stratified by severity of airway obstruction. Percentages of each PFT performance in the mild, moderate, and severe airway obstruction cohort are presented on top of each bar in the graph.

Figure 4

Percentages of medications prescribed, classified by severity of airway obstruction. Percentages of prescribed medications in the mild, moderate, and severe airway obstruction cohort are presented on top of each bar in the graph. LAMA = inhaled long-acting anticholinergic; ICS = inhaled corticosteroid; LABA = inhaled long-acting β-agonist; OCS = oral corticosteroid.