Associated Factors and Comorbidities of Airflow Limitation in Subjects Undergoing Comprehensive Health Examination in Japan – Survey of Chronic Obstructive Pulmonary Disease Patients Epidemiology in Japan (SCOPE- J)

Abstract

Purpose

To identify associated factors of having at least one of the airflow limitation, chronic cough/phlegm, and currently treated respiratory diseases in health examinees, and to describe the characteristics of each subgroup classified by comorbidities.

Subjects and Methods

This was an observational cross-sectional survey carried out in multiple regions of Japan. Subjects aged 40 years older, undergoing comprehensive health examination, were recruited. Airflow limitation was defined as having forced expiratory volume in 1 s/forced vital capacity lower than 70%. Associated factors of having at least one of the airflow limitation, chronic cough/phlegm, and currently treated respiratory diseases were examined by logistic regression analysis. Subgroup classification by comorbidity patterns was conducted by hierarchical cluster analysis.

Results

In a total of 22,293 subjects, 1520 (6.8%) had at least one of the airflow limitation, chronic cough/phlegm, and currently treated respiratory diseases. With this objective variable, the following explanatory variables were significantly associated: older age, higher total score in the chronic obstructive pulmonary disease assessment test (CAT) and coexistence of lung cancer (common in ever-smokers and never-smokers), higher pack-years, lower body mass index, higher C-reactive protein, without coexistence of diabetes mellitus (specific in ever-smokers), male sex, coexistence of anxiety, and sleep disorder (specific in never-smokers). Among the 1520 subjects, 1512 subjects with smoking history data were classified by comorbidity patterns into subgroups of “no comorbidities,” “mixed comorbidities,” “inflammatory comorbidities,” “overweight,” “underweight,” and “chronic kidney disease.” “Inflammatory comorbidities” were specific in ever-smokers, and “underweight” was specific in never-smokers.

Conclusion

Several factors were identified as associated factors of having at least one of airflow limitation, chronic cough/phlegm, and currently treated respiratory diseases and they were different between ever-smokers and never-smokers. Different comorbidity patterns were observed by smoking history. These findings could provide information to assist the management of subjects with COPD or at risk for COPD in the general population.

Keywords:

• spirometry
• lung function
• general population
• health checkup
• cluster analysis
• clinical characteristics

Acknowledgments

The authors are grateful to the examinees who participated in this survey and the staffs in the medical institutions who contributed to this survey. The following investigators took part in data collection of this survey: Dr. Takeshi Nawa (Hitachi General Hospital, Hitachi Ltd.), Dr. Kazuhiro Gotou (Health Park Clinic Kurosawa), Dr. Takashi Nakagawa (Omiya City Clinic), Dr. Koji Yamashita (Yotsukaido Tokushukai Hospital), Dr. Tatsuo Morikawa (Tokyo-Nishi Tokushukai Hospital), Dr. Takayuki Kashiwabara (JA Shizuoka Kohseiren Enshu Hospital), Dr. Tatsuya Shiraki (Matsubara Tokushukai Hospital), Dr. Ryo Kobayashi (Bell Clinic), Dr. Hiroshi Sonobe (Chugoku Central Hospital), Dr. Toshiki Fukui (Center for Preventive Medical Treatment, Olive Takamatsu Medical Clinic), Dr. Tokuji Motoki (Kochi Kenshin Clinic), Dr. Yasuhiro Ogata, Dr. Noritaka Higashi (Japanese Red Cross Kumamoto Health Care Center), Dr. Junko Aburaya (Koga Kenshin Center, Koga Ekimae Clinic), and Dr. Koki Ido (Osumi Kanoya Hospital).

Abbreviations

AP, angina pectoris; Anx, anxiety disorder; BMI, body mass index; CAT, chronic obstructive pulmonary disease assessment test; Cer, cerebrovascular disease; CKD, chronic kidney disease; COPD, chronic obstructive pulmonary disease; CI, confidence interval; Cr, serum creatinine; CRP, C-reactive protein; Dep, depression; DM, diabetes mellitus; eGFR, estimated glomerular filtration rate; FEV1/FVC, (forced expiratory volume in 1 s)/(forced vital capacity); Fra, fracture; GSK, GlaxoSmithKline; HbA1c, hemoglobin A1c; Inf, inflammation; LC, lung cancer; MI, myocardial infarction; NC, never-smokers/CKD; NM, never-smokers/mixed comorbidities; NN, never-smokers/no comorbidity; NO, never-smokers/overweight; NU, never-smokers/underweight; OP, osteoporosis; OR, odds ratio; OW, overweight; SC, smokers/CKD; SCOPE-J, Survey of Chronic Obstructive pulmonary disease Patients Epidemiology in Japan; SD, standard deviation; SI, smokers/inflammation; Sle, sleep disorder; SM, smokers/mixed comorbidities; SN, smokers/no comorbidity; SO, smokers/overweight; UW, underweight; WBC, white blood cell.

Author Contributions

All authors made a significant contribution to the work reported, whether that is in the conception, study design, execution, acquisition of data, analysis and interpretation, or in all these areas; took part in drafting, revising or critically reviewing the article; gave final approval of the version to be published; have agreed on the journal to which the article has been submitted; and agree to be accountable for all aspects of the work.

Disclosure

GlaxoSmithKline (GSK) was the funding source and was involved in all stages of this study (WEUSKOP6290). GSK also funded all costs associated with the publishing of the present manuscript. HO, NH, TN, and TF received funding for this study from GSK. TK is an employee of GSK and owns stock of the company; receives pay for part-time lecture from Shiga University of Medical Science. TS is an employee of GSK. The authors report no other potential conflicts of interest for this work.