Identification of subtypes in subjects with mild-to-moderate airflow limitation and its clinical and socioeconomic implications

• Published in: International journal of chronic obstructive pulmonary disease Vol. 12; pp. 1135 - 1144
• Main Authors: Lee, Jin Hwa, Rhee, Chin Kook, Kim, Kyungjoo, Kim, Jee-Ae, Kim, Sang Hyun, Yoo, Kwang-Ha, Kim, Woo Jin, Park, Yong Bum, Park, Hye Yun, Jung, Ki-Suck
• Format: Journal Article
• Language: English
• Published: New Zealand Dove Medical Press Limited 01.01.2017; Dove Medical Press Ltd; Dove Medical Press
• Subjects: Adult; Age Factors; Aged; Aged, 80 and over; airflow limitation; Asthma - diagnosis; Asthma - epidemiology; Biomarkers; Body Mass Index; Care and treatment; Chronic illnesses; Chronic obstructive lung disease; Chronic obstructive pulmonary disease; cluster; Cluster Analysis; Complications and side effects; costs; Databases, Factual; Diagnosis; Economic aspects; Female; Forced Expiratory Volume; Health Care Costs; Health Expenditures; Health insurance; Health Resources - economics; Health Resources - utilization; Humans; Income; Lung - physiopathology; Male; Middle Aged; Mortality; Nutrition Surveys; Original Research; Phenotype; Prognosis; Pulmonary Disease, Chronic Obstructive - economics; Pulmonary Disease, Chronic Obstructive - epidemiology; Pulmonary Disease, Chronic Obstructive - physiopathology; Pulmonary Disease, Chronic Obstructive - therapy; Republic of Korea - epidemiology; Respiratory Sounds - diagnosis; Risk Factors; Severity of Illness Index; Smoking - adverse effects; Smoking - epidemiology; socioeconomic; Socioeconomic Factors; subtype; Time Factors; Vital Capacity; Young Adult; South Korea; phenotype; cluster; health care utilization; asthma; overlap; COPD
• ISSN: 1178-2005; 1176-9106; 1178-2005
• DOI: 10.2147/COPD.S130140

The purpose of this study was to identify subtypes in patients with mild-to-moderate airflow limitation and to appreciate their clinical and socioeconomic implications. Subjects who were aged ≥20 years and had forced expiratory volume in 1 second (FEV ) ≥60% predicted and FEV /forced vital capacity <0.7 were selected from the fourth Korea National Health and Nutrition Examination Survey (KNHANES) in 2007-2012. The data were merged to the National Health Insurance reimbursement database during the same period. k-Means clustering was performed to explore subtypes. For clustering analysis, six key input variables - age, body mass index (BMI), FEV % predicted, the presence or absence of self-reported wheezing, smoking status, and pack-years of smoking - were selected. Among a total of 2,140 subjects, five groups were identified through k-means clustering, namely putative "near-normal (n=232)," "asthmatic (n=392)," "chronic obstructive pulmonary disease (COPD) (n=37)," "asthmatic-overlap (n=893)," and "COPD-overlap (n=586)" subtypes. Near-normal group showed the oldest mean age (72±7 years) and highest FEV (102%±8% predicted), and asthmatic group was the youngest (46±9 years). COPD and COPD-overlap groups were male predominant and all current or ex-smokers. While asthmatic group had the lowest prescription rate despite the highest proportion of self-reported wheezing, COPD, asthmatic-overlap, and COPD-overlap groups showed high prescription rate of respiratory medicine. Although COPD group formed only 1.7% of total subjects, they showed the highest mean medical cost and health care utilization, comprising 5.3% of the total medical cost. When calculating a ratio of total medical expense to household income, the mean ratio was highest in the COPD group. Clinical and epidemiological heterogeneities of subjects with mild-to-moderate airflow limitation and a different level of health care utilization by each subtype are shown. Identification of a subtype with high health care demand could be a priority for effective utilization of limited resources.