INTRODUCTION
Among respiratory diseases, asthma is one of the most burdensome
disorder both affects in childhood and adulthood. The prevalence was
estimated that there were more than 272 million people had asthma
worldwide in 2017.[1] Asthma not only increases financial, social,
and psychological burdens, but also makes a harmful impact on quality of
life, and is connected with comorbidities.[2] Interestingly, there
is increasing evidence presenting an connection between asthma and
constipation[3], a common condition affecting adults and children
globally and a frequent reason for visits to physicians. The mean global
prevalence of constipation in children is 12% and that in adult is
16%. [4] Even though constipation has few complications of
life-threatening, it can make physical and mental distress for patients
and their families, eventually impairing quality of life. Complications
of constipation included hemorrhoids, rectal prolapse, and fecal or
urine incontinence, which usually increases the frequency of
hospitalizations or outpatient department visits, leading to increased
burdens of health insurance.
Nowadays, constipation is seemed to be a causative factor in intestinal
dysbiosis[5] and therapeutic managements are increasingly
incorporating prebiotics, probiotics[6], or synbiotics with a view
to regulating the intestinal microflora[7, 8]. Moreover, recent
research has demonstrated that the gut microbiota would exert important
regulatory effects via the gut-lung axis.[9-11] For instance, gut
dysbiosis[12] and lower concentration of short-chain fatty acids
(SCFAs) in the bowel are found in patients with asthma. This condition
decreases the production of butyrate and propionate, leading to the
dysregulation of gut inflammation and the defect of the intestinal
epithelial barriers, resulting in leaky gut and allow penetration of
microorganisms and toxins into systemic circulation, thereby activating
Th2 immune responses, eventually contributing to airway inflammation.
Some research have suggested that allergic diseases might be associated
with constipation.[13, 14] Furthermore, previous study has
demonstrated that stool stasis in the long time could influence the
microbiota and environment of gut, resulting in deleterious effects on
mucosal immunity and intestinal motility.[15] Whether if
constipation predisposes susceptible people to asthma is unknown. At
present, there are still scanty data on the connection between
constipation and asthma in the literature. In addition, this association
has never been investigated using a large-scale national longitudinal
database. We hypothesized that constipation might influence the risk of
asthma and assessed this hypothesis by analyzing a real-world,
population-based retrospective cohort from National Health Insurance
Research Database (NHIRD) in Taiwan.