Bidirectional Association between Asthma and Irritable Bowel Syndrome: Two Population-Based Retrospective Cohort Studies.
BACKGROUND
There is a demonstrated association between asthma and irritable bowel syndrome (IBS). In this study, we examined the bidirectional association between asthma and IBS using a nationwide database.


METHODS
We conducted two retrospective cohort studies using data obtained from the National Health Insurance of Taiwan. Study 1 included 29,648 asthma patients newly diagnosed between 2000 and 2010. Study 2 included 29,875 IBS patient newly diagnosed between 2000 and 2010. For each study, four subjects without asthma and IBS were selected, respectively, frequency-matched by sex, age, and the diagnosis date. All four cohorts were followed up until the end of 2011 to estimate incident IBS for Study 1 and incident asthma for study 2. Adjusted hazard ratios (aHRs) were estimated using the Cox proportional hazards model after controlling for sex, age and comorbidities.


RESULTS
The incidence of IBS was 1.89 times higher in the asthma cohort than in the comparison cohort (8.26 vs. 4.36 per 1,000 person-years), with an aHR of 1.57 [95% confidence interval (CI) = 1.47-1.68]. The aHRs remained significant in all subgroups measured by sex, age and the presence of comorbidities. In contrast, the incidence of asthma was 1.76 times higher in the IBS cohort than the comparison cohort (7.09 vs. 4.03 per 1,000 person-years), with an aHR of 1.54 (95% CI = 1.44-1.64). Similarly, aHRs remained significant in all subgroups measured by sex, age and the presence of comorbidities.


CONCLUSIONS
The present study suggests a bidirectional association between asthma and IBS. Atopy could be a shared pathophysiology underlying this association, deserving a further investigation.
Graduate Institute of Clinical Medicine Science, College of Medicine, China Medical University, Taichung, Taiwan.|Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, China Medical University Hospital, Taichung, Taiwan.
Te-Chun
http://orcid.org/0000-0002-9427-1068
TC
Shen
Management Office for Health Data, China Medical University Hospital, Taichung, Taiwan.
Cheng-Li
CL
Lin
Children's Hospital, China Medical University Hospital, China Medical University, Taichung, Taiwan.
Chang-Ching
CC
Wei
Graduate Institute of Clinical Medicine Science, College of Medicine, China Medical University, Taichung, Taiwan.|Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, China Medical University Hospital, Taichung, Taiwan.
Chia-Hung
CH
Chen
Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, China Medical University Hospital, Taichung, Taiwan.
Chih-Yen
CY
Tu
Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, China Medical University Hospital, Taichung, Taiwan.
Te-Chun
TC
Hsia
Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, China Medical University Hospital, Taichung, Taiwan.
Chuen-Ming
CM
Shih
Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, China Medical University Hospital, Taichung, Taiwan.
Wu-Huei
WH
Hsu
Management Office for Health Data, China Medical University Hospital, Taichung, Taiwan.|Department of Health Services Administration, China Medical University, Taichung, Taiwan.|Faculty of Public Health, Mahidol University, Bangkok, Thailand.
Fung-Chang
FC
Sung
Graduate Institute of Clinical Medicine Science, College of Medicine, China Medical University, Taichung, Taiwan.|Management Office for Health Data, China Medical University Hospital, Taichung, Taiwan.|Department of Nuclear Medicine and PET Center, China Medical University Hospital, Taichung, Taiwan.
Chia-Hung
CH
Kao
D000328:Adult; D000367:Age Factors; D000368:Aged; D001249:Asthma / Q000453:epidemiology* / Q000209:etiology*; D016208:Databases, Factual; D005260:Female; D006801:Humans; D015994:Incidence; D043183:Irritable Bowel Syndrome / Q000453:epidemiology* / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D012107:Research Design; D012189:Retrospective Studies; D012307:Risk Factors; D013624:Taiwan / Q000453:epidemiology; D055815:Young Adult