Obstructive Lung Diseases: Airways 4 |

Subtype Analysis of Subject With Mild to Moderate Airflow Limitation FREE TO VIEW

Jin Hwa Lee, MD; Chin Kook Rhee, MD; Kwang Ha Yoo, MD; Jung Chang, MD
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Ewha Womans University School of Medicine, Seoul, Korea (the Republic of)

Copyright 2016, American College of Chest Physicians. All Rights Reserved.

Chest. 2016;150(4_S):859A. doi:10.1016/j.chest.2016.08.959
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SESSION TYPE: Original Investigation Poster

PRESENTED ON: Wednesday, October 26, 2016 at 01:30 PM - 02:30 PM

PURPOSE: The aim of this study was to identify subtypes in patients with mild to moderate airflow limitation and to evaluate clinical and socioeconomic implications of these subtypes.

METHODS: We analyzed data from the fourth Korean National Health and Nutrition Examination Survey and National Health Insurance claims in 2007-2012. Subjects who were 19 years old and more and had forced expiratory volume in 1 second (FEV1) ≥ 60% predicted and a ratio of FEV1 to forced vital capacity (FVC) < 0.7 were included. K-means clustering was performed to explore subtypes. For clustering analysis, six key input variables, age, body mass index (BMI), FEV1 % predicted, the presence or absence of self-reported wheezing, smoking status, and pack-years of smoking, were selected.

RESULTS: Among a total of 2,140 subjects, five subgroups identified through k-means clustering include putative “near-normal (n=232)”, “asthmatic (n=392)”, “COPD (n=37)”, “asthma-overlap (n=893)” and “COPD-overlap (n=586)” subtypes. Near-normal subgroup showed the oldest mean age (72±7 years) and highest FEV1 (102±8% predicted), and asthmatic subgroup was the youngest (46±9 years). Asthma-overlap subgroup showed the lowest FEV1 (77±9% predicted). COPD and COPD-overlap subgroups were male-predominant (100% and 98%, respectively) and all current or ex-smokers. When applying the lower limit of normal FEV1/FVC as a criterion for airway obstruction, asthma group had the highest prevalence of airway obstruction. While COPD, asthma-overlap and COPD-overlap subgroups showed high prescription rate of respiratory medicine, asthmatic subgroup had the lowest prescription rate despite the highest proportion of self-reported wheezing. Except asthmatic subgroup, comorbidities such as hypertension, diabetes mellitus, hyperlipidemia and coronary artery disease were frequently observed. Any respiratory medication was prescribed for 365 subjects (17%) and the highest prescription rate was in COPD subgroup (24%); 2nd, asthma-overlap (22%); 3rd, COPD-overlap (17%). Although COPD subgroup represents only 2% of total subjects, they showed the highest mean medical cost and health utilization, comprising 5% of the total cost. When calculating a ratio of total medical expense to household income, mean ratio was the highest in COPD subgroup.

CONCLUSIONS: Clinical and epidemiological heterogeneity was apparent among subjects with mild to moderate airflow limitation. Each subgroup may have a different level of demand for healthcare resources.

CLINICAL IMPLICATIONS: For appropriate distribution of limited healthcare resources, we need to clarify a subtype with high disease burden despite mild to moderate airflow limitation.

DISCLOSURE: The following authors have nothing to disclose: Jin Hwa Lee, Chin Kook Rhee, Kwang Ha Yoo, Jung Chang

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