Both the epidemiology and pathophysiology of constipation in older people point to the enormous importance of identifying predisposing causes for the condition in each affected individual. One prospective study examined baseline characteristics predictive of new-onset constipation in older nursing home residents, using the US Minimum Data Set. Seven percent (n = 1291) developed constipation over a 3-month period. Independent predictors were white race, poor consumption of fluids, pneumonia, Parkinson disease, allergies, decreased bed mobility, arthritis, more than five medications, dementia, hypothyroidism, and hypertension. The authors postulated that allergies, arthritis, and hypertension were associated primarily because of the constipating effect of drugs used to treat these conditions. Other studies have shown that institutionalization itself is an independent risk factor for symptom-based constipation in older people. Table 95-5 summarizes evidence-based risk factors of constipation in the older population.
TABLE 95-5RISK FACTORS FOR CONSTIPATION IN OLDER PEOPLE |Favorite Table|Download (.pdf) TABLE 95-5 RISK FACTORS FOR CONSTIPATION IN OLDER PEOPLE
| Polypharmacy (≥ 5 medications)  |
| Anticholinergic drugs (tricyclics, antipsychotics, antihistamines, antiemetics, drugs for detrusor hyperactivity)  |
| Opiates  |
| Iron supplements  |
| Calcium channel antagonists (nifedipine and verapamil)  |
| Calcium supplements  |
| Nonsteroidal anti-inflammatory drugs  |
|Impaired mobility  |
|Nursing home residency  |
|Neurological conditions |
| Dementia  |
| Parkinson disease  |
| Diabetes  |
| Autonomic neuropathy  |
| Stroke  |
| Spinal cord injury or disease  |
|Depression  |
|Dehydration  |
|Low dietary fiber  |
|Metabolic disturbances |
| Hypothyroidism |
| Hypercalcemia |
| Hypokalemia |
| Uremia |
| Patients receiving renal dialysis  |
|Mechanical obstruction (eg, tumor, rectocele) |
|Lack of privacy or comfort |
|Poor toilet access  |
Impaired mobility is a common risk factor for constipation in older people. Greater physical activity (including regular walking) is associated with less self-reported and symptom-specific constipation in older people living both at home and in long-term care. Reduced mobility was found to be the strongest independent correlate of heavy laxative use among nursing home residents, following adjustment for age, comorbidity, and other relevant clinical factors. Gut transit time in older subjects was measured independently as 3 days in ambulant, and 3 weeks in bedridden patients, although comorbid factors were likely to be contributory. A study of healthy young male volunteers showed that after only 1 week of bed rest, both transit through the sigmoid colon and stool frequency were reduced. It is well documented that exercise increases colonic propulsive activity (“jogger’s diarrhea”), especially when measured postprandially. In a population survey of younger women (36–61 years), daily physical activity was associated with less constipation (defined as two or fewer bowel movements per week), and the association strengthened with increased frequency of physical activity. This suggests that increasing physical activity in adulthood may reduce the likelihood of constipation problems in older age.
Polypharmacy increases the risk of constipation in older patients, particularly in nursing homes where each individual takes an average of six prescribed medications per day. Anticholinergic medications reduce contractility of the smooth muscle of the gut via an antimuscarinic effect at acetylcholine receptor sites, and in some cases (eg, patients with schizophrenia taking neuroleptics), long-term use may result in chronic megacolon. In two cross-sectional studies of nursing home residents, anticholinergic antidepressants were independently associated with daily laxative use following adjustment for age, gender, function, and cognition. Anticholinergic neuroleptics and antihistamines were also independently associated in one of the studies; nonanticholinergic sedatives, however, were not found to be constipating. A study of 532 community-dwelling older US veterans found that among the 27% using anticholinergic drugs, the rate of constipation (42%) was significantly greater than those not using the drugs.
While older people are very susceptible to the constipating effects of opiate analgesia, a study of nursing home residents with persistent nonmalignant pain found that there was no increased rate of constipation in chronic opiate users over a 6-month period compared to those not taking opiates. They also observed a general improvement in functional status and social engagement. Constipation in chronic opiate users can be effectively managed (by laxative or suppository coprescription where needed)—an important finding as chronic pain is often undertreated in older people perhaps owing to fear of the adverse effects of analgesic drugs. Community-based studies of adults receiving opiates for chronic pain have shown equal constipation risk for all sustained-release oral preparations. Transdermal patches (eg, fentanyl), however, are associated with lower risk of constipation than oral preparations.
All types of iron supplements (sulphate, fumarate, and gluconate) cause constipation, the constipating factor being the amount of elemental iron absorbed. Slow-release preparations have a lesser impact on the large bowel, but this is because they tend to carry the iron past the first part of the duodenum into an area of the gut where elemental iron absorption is poorer. Administration of iron sulfate in doses greater than 325 mg/day does not substantially increase iron absorption in older persons and may significantly increase gastrointestinal side effects. Intravenous iron does not cause constipation and may be an alternative in patients with chronic anemia (eg, chronic kidney disease) who have symptomatic constipation on oral iron.
In a 5-year study of calcium supplementation in older women, the only side effect was constipation (treatment 13.4% vs placebo 9.1%). The study showed that calcium supplementation reduced bone loss and turnover and fracture rates in older women who took it, but long-term compliance was poor, and constipation may have contributed to this.
Calcium channel antagonists impair lower gut motility, particularly in the rectosigmoid, by inhibiting calcium uptake into smooth muscle cells and altering intraluminal electrolyte and water transportation. Severe constipation has been reported in older patients taking calcium channel antagonists, with nifedipine and verapamil being the most potent inhibitors of gut motility in this class of drugs.
Nonsteroidal anti-inflammatory drugs (NSAIDs) increase the risk of constipation in older people, most likely through prostaglandin inhibition. In a large case-controlled primary care study, constipation and straining was a more common reason for stopping NSAIDs than dyspepsia. NSAIDs have also been implicated in causing stercoral perforation in patients with chronic constipation.
Aluminium antacids have been associated with constipation in older people living in both nursing homes and in the community.
Low consumption of wheat bran, fiber, vegetables, fruit, rice, and calories can all predispose toward constipation. A UK survey showed that consumption of fruit, vegetables, and bread decreases with advancing age. It has been suggested that the prevalence of constipation is rising because modern food processing produces refined food with low roughage. Community studies of older Europeans who eat a Mediterranean diet rich in fruit, vegetables, and olive oil show a low prevalence of constipation (4.4% in people aged > 50). Conversely, a German questionnaire survey of adults with and without constipation reported that chocolate, white bread, and bananas were the foodstuffs most strongly perceived to harden stools.
Low-calorie intake in older people (adjusted for fiber intake) has been linked to constipation. One study looked at nutritional factors across all nursing homes in Finland and found that malnutrition and constipation were associated. This may be a two-way association in that marked constipation or fecal impaction can cause anorexia, while low-calorie intake can promote constipation.
Constipation is a recognized problem in patients receiving enteral nutrition. A prospective survey from Spain of hospitalized patients (mean age 76) receiving nasogastric tube feeding identified constipation as a complication of treatment in 30%. Enteric feeding products containing fiber are available, though there are no data on whether constipation is any less of a problem with their use.
Low-fluid intake in older adults has been related to symptomatic constipation in epidemiologic surveys and to slow colonic transit. In patients with Parkinson disease, low water intake is correlated with severity of constipation. Withholding fluids over a 1-week period in young male volunteers significantly reduced stool output. Older people are at greater risk of dehydration and resulting constipation because of
Impaired thirst sensation
Less effective hormonal responses to hypertonicity
Limited access to drinks because of coexisting physical or cognitive impairments
Voluntary fluid restriction in an attempt to control urinary incontinence
A large Japanese survey of constipation symptoms found that alcohol consumption was a preventive factor in men. A population survey of middle-aged women in the United States showed that daily alcohol consumption (exceeding 12 g/day) and low-moderate caffeine intake were independently inversely related to infrequent bowel movements. Black coffee has been shown to increase colonic motility specifically in the rectosigmoid within 4 minutes of ingestion in young healthy volunteers (a reaction not observed with ingestion of hot water), implying that caffeine triggers the gastrocolic reflex.
Patients with Parkinson disease suffer from three primary pathologies that lead to constipation:
Primary degeneration of dopaminergic neurons in the myenteric plexus resulting in prolonged colorectal transit
Pelvic dyssynergia causing rectal outlet delay and prolonged straining
Small increases in intra-abdominal pressures on straining (compared with age-matched controls)
Constipation can become prominent early in the course of the disease, even 10 to 20 years prior to motor symptoms. In a 24-year longitudinal study in Honolulu, less than one bowel movement a day was associated with a threefold elevated risk of future Parkinson disease in men. A study of patients at a Parkinson disease clinic found that 59% were constipated according to the Rome criteria (vs 21% in age-matched control group without neurological disease), and 33% were very concerned by their bowel problem. Antiparkinsonian drugs can further exacerbate constipation. Pelvic dyssynergia affects 60% of people with Parkinson disease and may be hard to treat. Botulinum toxin injected into the puborectalis muscle has been used to improve rectal emptying in Parkinson disease patients with good effect, though repeat injections every 3 months are required to maintain clinical benefit.
Dementia predisposes individuals to rectal dysmotility, partly through ignoring the urge to defecate. A study in which young men deliberately suppressed defecation resulted in prolonged transit through the rectosigmoid with a marked reduction in frequency of bowel movements. Epidemiological studies show a significant association between cognitive impairment and nurse-documented constipation in nursing home residents. Patients with non-Alzheimer dementias (Parkinson disease, Lewy body, vascular dementia) compared to those with Alzheimer dementia are more likely to suffer from autonomic symptoms, including constipation.
Depression, psychological distress, and anxiety are all associated with increased self-reporting of constipation in older persons. In certain cases, the symptom of constipation is a somatic manifestation of psychiatric illness. A careful assessment is required to differentiate subjective complaints from clinical constipation in depressed or anxious patients.
Constipation affects 60% of those recovering from stroke while undergoing rehabilitation, and a high number of these have combined rectal outlet delay and slow transit constipation. For stroke survivors living in the community, problems relating to bowel evacuation are greatly worsened by difficulties accessing the toilet owing to functional impairment. Weakness of abdominal and pelvic muscles following stroke also contribute to problems with evacuation.
Spinal Cord Injury/Disease
Constipation affects the majority of people with spinal cord disease or injury. Age and duration of injury interact to promote complications of chronic constipation such as acquired megacolon, which affects more than half of patients with spinal cord injury. Lumbar stenosis in older people caused by degenerative joint disease may lead to cauda equina problems with severe rectal outlet delay. One study in younger people showed that an average of 27 of rectosigmoid emptying was achieved with each defecation in patients with cauda equina syndromes, versus 81% in healthy controls.
A Turkish study of outpatients with type 2 diabetes showed that 56% complained of constipation (vs 30% of controls). Neuropathy symptom scores correlated with laxative usage and straining. Diabetic patients with autonomic neuropathy are more likely to be constipated because of markedly slowed transit throughout the colon and impairment of the gastrocolic reflex. However, one-third of diabetic patients with constipation do not have neuropathic symptoms, so additional potentially reversible factors should be considered particularly in older people (eg, drugs, mobility, fluids). Indeed, a US community study found that constipation and/or laxative use was increased in type 1 versus type 2 diabetic men, but this difference was associated with use of calcium channel blockers rather than with neuropathy symptoms. Acute hyperglycemia inhibits the gastrocolic reflex and colonic peristalsis, so glycemic control is important. Colonic transit time in immobile older people with diabetes is extremely prolonged at 200 ± 144 hours. An Israeli study showed that this very long transit time in long-term care residents with diabetes can be significantly reduced by administering acarbose, an α-glucosidase inhibitor with a potential adverse effect of causing diarrhea. Overall, gut dysmotility can lead to bacterial overgrowth and the clinical problem of explosive diarrhea; treatment with erythromycin and long-term motility agents such as metoclopramide should be considered in these individuals.
Hypokalemia produces neuronal dysfunction that minimizes acetylcholine stimulation of gut smooth muscle and so prolongs transit through the gut. It should be excluded in cases of colonic pseudo-obstruction and sigmoid volvulus. Hypercalcemia causes conduction delay within the extrinsic and intrinsic innervation of the gut. Surgical treatment of hyperparathyroidism reverses the neuromuscular bowel dysfunction seen with this condition. Patients with myxedema have been observed to have edema of the gut wall with mucopolysaccharide deposition, although whether this contributes to the colonic hypomotility seen commonly in clinical hypothyroidism is uncertain. Patients on long-term renal dialysis have prolonged age-adjusted transit time, more so in hemo- than peritoneal dialysis. In a questionnaire study in Japan, 63% of hemodialysis patients complained of constipation. Important contributors to this problem were thought to be high (49%) use of resin to avoid hyperkalemia, suppression of the defecation urge while undergoing dialysis, and low-fiber intake. Resin administration also places older inpatients at risk of fecal impaction.
Colorectal cancer has been linked with both constipation and use of laxatives, although this risk association is likely to be confounded by the influence of underlying habits. One study, adjusted for age and potential confounders, found that having fewer than three reported bowel movements a week was associated with a greater than twofold risk of colon cancer, with the association being most strong in black women. As the prevalence of colorectal cancer increases with age, index of suspicion should be higher in older adults. Constipation alone, however, is not an indication for proceeding to colonoscopy (see below).
Posterior vaginal wall prolapse and rectocele are common in older multiparous women. These individuals have an increased risk of rectal outlet delay, particularly incomplete emptying and need for digital evacuation. This is presumably caused by mechanical obstruction, as this association is not seen in women with anterior pelvic prolapse.