A new large-scale medical study has revealed that constipation is far more widespread and serious than previously thought, affecting nearly one in three adults and placing millions of people at risk of long-term health complications. The research, conducted in Japan among more than 8,600 patients who underwent colonoscopy, found that constipation is strongly associated with aging, female gender, diabetes, heart disease, kidney failure, and the use of several commonly prescribed medications. Alarmingly, more than 60 percent of patients continued to experience constipation despite taking laxatives, highlighting a growing challenge of treatment-resistant or “refractory” constipation.
Constipation is often considered a minor digestive inconvenience, but medical experts increasingly view it as a condition that significantly reduces quality of life and may be linked to serious health risks, including cardiovascular disease and increased mortality. This study provides one of the most detailed pictures so far of how common constipation is and why so many patients do not respond adequately to treatment.
Study Design and Patient Population
The research was conducted at the National Center for Global Health and Medicine in Tokyo using an electronic medical database. Data were collected from patients who underwent colonoscopy between October 2015 and March 2020.
Patients with colon cancer, inflammatory bowel disease, or a history of lower gastrointestinal surgery were excluded to ensure that the analysis focused on functional constipation rather than structural disease. All participants completed standardized questionnaires covering demographic characteristics, medical conditions, medication use, and gastrointestinal symptoms.
To assess symptoms, researchers used the Gastrointestinal Symptoms Rating Scale (GSRS), a validated questionnaire that measures digestive discomfort over the previous week on a seven-point scale. Constipation was defined as difficulty emptying the bowels or having hard stools. Refractory constipation was defined as persistent symptoms in patients already taking one or more laxatives.
Prevalence of Constipation Symptoms
The findings showed that constipation is extremely common. Of the 8,621 patients included in the study, 33.3 percent reported constipation symptoms. More than a quarter experienced reduced bowel movements, while about the same proportion reported hard stools.
These figures are consistent with global data suggesting that constipation affects about 16 percent of adults overall and more than 30 percent of people over the age of 60. In Japan, previous surveys have indicated that more than half of adults believe they experience constipation at some point in their lives.
The study also revealed a strong overlap between constipation and irritable bowel syndrome (IBS). Nearly 45 percent of patients with constipation met diagnostic criteria for IBS, including both constipation-predominant IBS and mixed bowel habit IBS. This suggests that constipation is often part of a broader disorder involving abnormal gut sensitivity and bowel motility.
Age and Gender as Key Risk Factors
Age emerged as one of the most important predictors of constipation. Patients aged 65 years and older were significantly more likely to suffer from constipation than younger adults. This finding reflects the natural slowing of intestinal movement with aging as well as the higher burden of chronic disease in older populations.
Gender differences were also striking. Women were nearly 1.7 times more likely to experience constipation than men. Hormonal influences, pelvic floor differences, and lifestyle factors are believed to contribute to this disparity. Interestingly, the proportion of women with constipation decreased with age, suggesting that younger and middle-aged women may be particularly vulnerable.
Body weight played a role as well. Underweight individuals had higher rates of constipation compared with those of normal or higher body mass index, indicating that nutritional status and muscle mass may influence bowel function.
Chronic Diseases Linked to Constipation
The study identified several chronic medical conditions that significantly increased the risk of constipation. These included diabetes, chronic kidney failure, stroke with paralysis, chronic obstructive pulmonary disease (COPD), ischemic heart disease, dementia, and collagen vascular diseases.
Among these, chronic kidney failure showed one of the strongest associations, with patients facing more than double the risk of constipation compared with those without kidney disease. Diabetes also stood out as a major risk factor, reflecting the impact of nerve damage and reduced intestinal movement in diabetic patients.
Patients with COPD were also more likely to experience constipation, possibly because reduced physical activity and medication side effects contribute to slower bowel function. Heart disease patients, many of whom restrict fluid intake and use diuretics, may experience dehydration that worsens constipation.
Medications That Increase Constipation Risk
Medication use was another major contributor to constipation. The study found higher constipation rates among patients taking opioids, benzodiazepines, antiparkinsonian drugs, antidepressants, and antipsychotics. Opioid users had more than twice the risk of constipation compared with non-users.
These medications affect bowel function through their effects on the nervous system and intestinal muscles. Opioids slow gut movement by acting on opioid receptors in the intestines, while benzodiazepines and anticholinergic drugs interfere with nerve signals that stimulate bowel contractions. Calcium channel blockers and common pain relievers such as NSAIDs were also linked to higher constipation rates, though their effects were less pronounced.
After adjusting for multiple factors using statistical models, researchers confirmed that older age, female sex, diabetes, chronic kidney failure, stroke with paralysis, COPD, ischemic heart disease, and the use of opioids, benzodiazepines, and antiparkinsonian medications were independent predictors of constipation.
The Challenge of Refractory Constipation
One of the most concerning findings was that treatment often failed to resolve symptoms. Among more than 1,100 patients who were taking laxatives, 61.3 percent still reported constipation. Even more troubling was the observation that symptom persistence increased as more medications were added.
Patients taking one laxative still had a symptom rate of nearly 58 percent, while those taking two or more drugs had rates approaching 70 percent or higher. This pattern suggests that simply increasing medication does not address the underlying problem for many patients and that refractory constipation represents a major clinical challenge.
The most commonly used treatments included osmotic laxatives, stimulant laxatives, herbal Kampo medicine, bulk-forming agents, and newer secretagogues such as linaclotide and lubiprostone. Despite these options, a large proportion of patients remained symptomatic.
IBS and Diabetes as Predictors of Treatment Failure
Further analysis revealed that irritable bowel syndrome and diabetes were the strongest predictors of refractory constipation. Patients with IBS were three times more likely to experience persistent symptoms despite medication, while those with diabetes had a significantly higher risk as well.
In IBS, abnormal gut sensitivity plays a central role. The intestines overreact to normal stretching and movement, producing discomfort and disrupting coordinated bowel contractions. This visceral hypersensitivity makes standard laxatives less effective because the problem is not simply slow transit but abnormal nerve signaling.
Diabetes contributes to constipation through nerve damage known as diabetic neuropathy. This condition affects the autonomic nerves that control intestinal movement, leading to slower transit time, reduced sensation of rectal fullness, and impaired defecation reflexes. Over time, the colon becomes weak and unresponsive, resulting in chronic and treatment-resistant constipation.
Public Health Implications
Constipation significantly affects quality of life, limiting social activities and daily functioning. Patients with chronic constipation are more likely to experience anxiety and depression and to seek repeated medical care. Healthcare systems also bear a growing burden from long-term constipation management.
There is increasing evidence that constipation is associated with cardiovascular disease and higher overall mortality. This suggests that constipation may serve as a marker of underlying systemic illness rather than merely a digestive complaint.
As populations age and chronic diseases such as diabetes and heart disease become more common, the burden of constipation is expected to rise further.
Strengths and Limitations of the Study
The study’s strengths include its large sample size, use of validated symptom questionnaires, and exclusion of patients with colon cancer or inflammatory bowel disease. It is also one of the few investigations to focus specifically on refractory constipation.
However, the researchers acknowledged limitations. The data came from a single hospital and may not represent the general population. Some conditions known to influence bowel function, such as thyroid disorders, were not included. In addition, patients too ill to complete questionnaires were excluded, which may have introduced selection bias.
Despite these limitations, the findings provide valuable insight into constipation epidemiology and treatment challenges.
Conclusion
This large-scale study confirms that constipation is far more common and complex than many people realize. Approximately one-third of adults suffer from constipation, and more than 60 percent of those treated with medication continue to experience symptoms. Women, older adults, and patients with chronic illnesses such as diabetes and kidney disease are at particularly high risk.
The results underscore the need to treat constipation as a serious medical condition rather than a minor inconvenience. Greater awareness, early diagnosis, and personalized treatment strategies are essential to reduce its long-term impact on health and quality of life.
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