36: Constipation

Chronic constipation is one of the most frequent gastrointestinal disorders encountered among older adults in clinical practice. Constipation is often associated with other abdominal complaints (pain, bloating, and gas), as well as decreased overall well-being. It may involve infrequent defecation, difficulty in passing stool, or incomplete evacuation of stool. Physicians often define constipation as infrequent passage of stool; however, patients often define it as straining to defecate or sensation of incomplete evacuation. For chronic constipation to be diagnosed, symptoms should be present for at least 12 weeks.

Chronic constipation disproportionately affects older individuals with an estimated prevalence of 40% among people older than age 65 years. Women are also at increased risk, having 2–3 times more constipation than men. African Americans also exhibit increased risk. Many community-dwelling older adults commonly use nonprescription preparations, such as stimulant and bulking laxatives. Nearly 85% of physician visits for constipation result in a prescription for laxatives and more than $820 million are spent per year on nonprescription agents. Few resources are available to health care providers to guide them in an evidence-based approach to this common problem.

Symptoms & Signs

Symptoms of constipation reported by patients often differ from definitions and classification from clinical criteria. Patients often report symptoms related to bloating, fullness, and incomplete evacuation. However, clinicians often focus on stool frequency and consistency to define constipation. The Rome III criteria, published in 2006, define chronic constipation as symptoms that have persisted for the past 3 months with an onset at least 6 months prior to diagnosis, with the following 3 criteria being met:

1. Must include 2 or more of the following:

   1. Hard or lumpy stool in ≥25% of defecations

   2. Straining during ≥25% defecations

   3. Sensation of incomplete evacuation for at least 25% of defecations

   4. Sensation of anorectal obstruction or blockage for ≥25% of defecations

   5. Manual maneuvers to facilitate ≥25% of defecations (eg, digital evacuation, support of the pelvic floor)

   6. Fewer than 3 defecations per week

2. Loose stools are rarely present without use of laxatives

3. Insufficient criteria for irritable bowel syndrome (IBS)

Differentiating symptoms of chronic constipation from IBS with constipation (IBS-C) may not be as important in older adults, as age ≥50 years is associated with lower rates of IBS. However, management can differ between the 2 diagnoses. IBS-C is defined by recurrent abdominal pain or discomfort for at least 3 days per month in the previous 3 months (onset ≥6 months prior to the diagnosis) that is associated with at least 2 of the following:

1. Improvement of pain or discomfort upon defecation

2. Onset associated with change in frequency of stool

3. Onset associated with a change in form or appearance of stool

Symptoms of hematochezia, family history of colon cancer/inflammatory bowel disease, anemia, positive fecal occult blood test, unexplained weight loss ≥10 pounds, constipation that is refractory to treatment, and new-onset constipation without evidence of potential primary cause are all considered “alarm” symptoms and may necessitate further evaluation with more invasive testing, if indicated.

Diagnostic Studies

In most cases, patients with chronic constipation do not warrant extensive diagnostic evaluation. Older patients who have “alarm” symptoms should consider the benefits and risks of doing further evaluation with colonoscopy or other invasive testing.

The clinical evaluation should consist of a thorough history containing the above questions and an appropriate physical examination and laboratory testing. Physical examination should be performed, including a rectal exam, palpating for hard stool, assessing for masses, anal fissures, sphincter tone, prostatic hypertrophy in males, hemorrhoids, push effort during attempted defecation, and posterior vaginal masses in women. Laboratory testing should include a complete blood count, serum calcium, thyroid function tests, and fecal occult blood testing. It is also important to ask about stool frequency, consistency, and other associated symptoms, such as straining and fecal incontinence (see “Fecal Impaction” below). Radiologic examination with abdominal plain films may also detect significant stool retention in the colon and suggest the diagnosis of megacolon. Marker studies or colonic transit studies can be used in patients with infrequent defecation. A marker study involves ingestion of radiopaque markers with a subsequent abdominal radiograph to detect the markers in the right, left, or rectosigmoid colon. Other forms of transit time evaluation with radioactive tracers and wireless motility capsule technologies (that record data after ingestion) are also available.

The causes of constipation can be categorized as primary (types of constipation) or secondary (eg, caused by a medical diagnosis or use of medications) in nature. Table 36–1 lists primary causes of constipation and Table 36–2 lists secondary causes.

Many prescription drugs have constipation and slowed colonic motility as side effects. Constipation-inducing medications in older adults include opioids, anabolic steroids, anticonvulsants, anticholinergic agents, antihypertensive agents, tricyclic antidepressants, antiparkinsonian agents, antipsychotics, diuretics, and sympathomimetic drugs. Nonprescription agents also implicated in causing constipation include antihistamines, calcium supplements, iron supplements, antidiarrheal agents, nonsteroidal antiinflammatory drugs (NSAIDs), and calcium- and aluminum-containing antacids.

Once secondary causes of constipation have been evaluated and addressed as possible, the management of constipation varies according to type. The treatment and prevention of slow-transit constipation includes patient education about bowel habits, dietary changes, and drug therapies. Management of dyssynergic defecation involves biofeedback, relaxation exercises, and suppository programs. Patients with slow-transit and dyssynergic defecation should receive treatment for the dyssynergia first before other measures are started.

Nonpharmacologic Therapy

Nonpharmacologic treatment options or lifestyle modifications involve diet, exercise, and biofeedback (if dyssynergic defecation is diagnosed). Very little clinical trial evidence exists to support dietary and exercise recommendations that are recommended to prevent or treat constipation, especially in older adults.

Dietary options include increasing fluid and fiber. In one study of 883 people >70 years of age, there was no association between estimated fluid intake and constipation; however, in 21,000 nursing home residents a weak association was found between decreased fluid intake and constipation. Adequate fluid intake may be an important general health recommendation and may also impact treatment of constipation, especially with fiber supplementation. The daily recommended amount of fiber is 20–35 g/day, but most Americans only consume 5–10 g/day. Increasing daily fiber intake through dietary measures is recommended. Information should be given on the fiber contained in common foods. Patients should increase fiber intake slowly—5 g/day at 1-week intervals—until the recommended intake is attained. Patients should be informed that an immediate response is not expected, and that flatus and bloating may occur, but are usually temporary. Increasing fiber intake gradually may help with some of these unwanted side effects.

Probiotics have also been tested for the treatment of constipation. Lactobacillus and Bifidobacterium are symbiotics flora in the large intestine that may promote colonic mucosal health. Low levels of both have been reported in individuals with chronic constipation. Although properly controlled trials are lacking, some prospective evidence does report efficacy of probiotics (Lactobacillus) improving constipation in nursing home residents. Survival and viability of these probiotic bacteria in a commercial form has not been standardized for these treatments to have high levels of evidence for clinical use.

Increased physical activity is associated with lower rates of constipation in older adults. Physical inactivity may also be associated with reduced colonic transit time. Exercise should be encouraged in older adults, when appropriate.

Biofeedback is an effective treatment for dyssynergic defecation, which is characterized by paradoxical contraction or failure to relax the pelvic floor muscles during defecation. Biofeedback can involve both sensory training and muscle contraction/relaxation techniques. In patients with dyssynergic defecation, biofeedback was consistently found to be more effective than continuous use of polyethylene glycol (PEG, MiraLAX), standard therapy (other types of stool softners and laxatives), sham therapy (therapy aimed at overall body relaxation), or the use of diazepam in 4 randomized controlled trials. However, trials are needed to determine the efficacy of biofeedback in older adults.

Many people will have already tried fluids, fiber, and fitness, but often not in a sustained manner. Most Americans do not consume enough dietary fiber and increasing the intake of fiber and fluids may be enough to help prevent constipation in healthy older adults. Consideration may also involve nutritional expertise, physical therapy (when appropriate), and family/caregivers in making dietary and exercise changes for the treatment of constipation. Preventing and treating constipation with nonpharmacologic and pharmacologic treatments may be needed for older adults in specific situations—that is, in the postoperative period, during hospitalization, or other health care environments when decreased mobility is anticipated—and when using acute or chronic opioid medications.

Pharmacologic Therapy (Including Nonprescription Preparations)

The main categories of medications for prevention of constipation (nonprescription preparations) are bulking agents, stool softeners/emollients, and osmotic agents. The main categories for the treatment of chronic constipation are bulking agents, stool softners/emollients, osmotic agents, stimulants, chloride change activators, 5-HT₄ receptor agonists, and guanylate cyclase-c receptor agonists. Table 36–3 lists the pharmacologic treatments for constipation based on existing evidence from the American College of Gastroenterology Chronic Constipation Task Force.

Bulking agents—

Bulking agents expand with water to increase the bulk of the stool with the result of having softer stool. Patients may need to try different types of fiber to achieve the desired outcome, including minimization of side effects. Some patients may better tolerate soluble and synthetic bulking agents than insoluble agents. Adequate hydration with bulking agents may be necessary for the desired outcome. Patients taking fiber need to increase their fluid intake to 30 mL/kg of body weight daily to avoid worsening of constipation or impaction. Fiber may also inhibit the absorption of other drugs and should be taken 1 hour before or 2 hours after other medications. Bulking agents should also be increased slowly over weekly periods to avoid side effects, similar to increasing dietary fiber consumption. Bulking agents are considered to be first-line agents for constipation. However, many older adults may not be good candidates for using a bulking agent. Some examples of when bulking agents may not be the first-line agent for older adults with constipation include when taking high doses of narcotic medications, difficulty with swallowing or dysphagia (because of the consistency of certain types of fiber when mixed with water), anyone with surgical resection of the majority of the colon, patients who have a suspected rectal mass or possible bowel obstruction, and older adults who do not consume adequate amounts of fluid.

Stool softeners and emollients—

Stool softeners and emollients are effective by having a detergent effect on the stool consistency. This class of medications for constipation is well tolerated and does not interfere with other medications. Although no placebo-controlled trials exist for the use of these medications, in a study in 170 patients, psyllium husk was as effective for softening stools and had similar overall efficacy as docusate. Mineral oil is also an emollient and may help lubricate the stool through the colon. Aspiration and lipoid pneumonia are known risks of using mineral oil in older adults. Stool softeners are often used when bulking agents do not work or are not preferred. Because of their mechanism of action as a detergent, stool softeners can also be used in combination with bulking agents. Like bulking agents, stool softeners alone are not good treatments for older adults on narcotic medications who have constipation.

Osmotic laxatives—

Osmotic laxatives promote the secretion of water into the intestinal lumen by osmotic activity and the hyperosmolar nature of these medications. PEG has the best evidence of use and is now available over-the-counter as a treatment for occasional constipation. It improves stool frequency and consistency in patients with chronic constipation. Studies suggest that PEG can be dose adjusted or used every other day with efficacy. An open-label study with 117 participants, ≥65 years of age, using PEG over 12 months reported relatively few side effects and no serious adverse events related to the medication. A recent evidence-based review article concluded that PEG may be better for constipation symptoms than lactulose. Common use of PEG or magnesium hydroxide-containing preparations (milk of magnesia) in patients with congestive heart failure or chronic renal disease should be done with extreme caution as they can cause electrolyte imbalances, such as hypokalemia and diarrhea, further worsening fluid–electrolyte balances. Osmotic agents are useful when first-line bulking agents and/or stool softners are not effective.

Stimulants—

Stimulants, such as senna and bisacodyl-containing compounds, increase intestinal motility by increasing peristaltic contractions. Stimulants also decrease water absorption from the lumen. Patients usually report more unfavorable side effects from these medications: abdominal discomfort and cramping. Evidence exists for using bisacodyl given placebo-controlled studies. Evidence also exists for senna, although fewer clinical trials exist comparing senna to placebo than that for bisacodyl. There is no evidence to support that long-term use of stimulant laxatives damages the enteric nervous system. Stimulant laxatives have been associated with melanosis coli. The presence of melanosis coli (which may be seen on colonscopy) is a marker of chronic laxative use and may not indicate any other clinical consequences.

5-HT4 (serotonin) agonists—

5-Hydroxytryptamine receptor subtype 4 (5-HT₄) receptors are found in the colon and mediate the release of other neurotransmitters that may initiate peristaltic action. These prokinetic agents enhance gastrointestinal motility by increasing intestinal contractions. These drugs are no longer marketed in the United States, and little data exist for use in older adults. Other prokinetic agents, such as metoclopramide and erythromycin, have not been formally evaluated for the treatment of constipation. Because of the side-effect profile in older adults, metoclopramide should not be used for chronic constipation.

Colonic secretagogues (increases intestinal fluid secretion)

Chloride channel activators—

Lubiprostone is a chloride channel activator that improves motility in the intestine by increasing intestinal fluid secretion without altering serum electrolyte concentrations. Retrospective data from 3 pooled clinical trials of lubiprostone in older patients (n = 57) without significant comorbidities showed improvement in stool frequency, stool consistency, and decreased straining compared to patients taking placebo. The side effects of this medication include nausea, diarrhea, headache, abdominal distention, and abdominal pain, and are generally well-tolerated.

Guanylate cyclase C receptor antagonists—

Linaclotide is another colonic secretagogue that stimulates intestinal fluid secretion and transit. Two large phase 3 trials have been performed in patients with chronic constipation, and the linaclotide-treated groups had significantly higher rates of 3 or more complete spontaneous bowel movements per week and in increase in 1 or more complete spontaneous bowel movements from baseline during at least 9 of 12 weeks compared with placebo. The most common adverse event was diarrhea, which led to discontinuation of treatment in approximately 4% of patients. The long-term risks and benefits of linaclotide in treating chronic constipation remain unknown.

Opioid antagonists—

Two peripherally acting mu opioid receptor antagonists exist that may have some role in the treatment of opiate-induced constipation and paralytic ileus (alvimopan and methylnaltrexone). Data are lacking currently in older adults. These medications act peripherally and do not cross the blood brain barrier, thus not affecting the analgesic properties of opioids.

Constipation is an important factor in the development of fecal impaction in older adults, especially in those who have limited mobility in the community and in long-term care settings. Fecal impaction results from an individual’s lack of ability to sense and respond to the presence of stool in the rectum. Mobility and decreased rectal sensation contribute to fecal impaction in older adults.

To diagnosis fecal impaction, a digital rectal examination is very important. Although impacted stool may not be a hard consistency, the key to diagnosis is finding a large amount of stool in the rectum. Fecal impaction can also occur in the proximal rectum or sigmoid colon, which would not be detected on digital rectal examination. If fecal impaction is suspected, obtaining an abdominal radiograph may help identify the area of impaction.

The management of fecal impaction involves disimpaction and colon evacuation, followed by a maintenance bowel regimen. Digital disimpaction can be used to fragment a large amount fecal material in the rectum. Following digital disimpaction, a warm-water enema with mineral oil may be used to soften the impaction and assist with emptying the stool from the impacted area. Very little evidence exists for guiding the treatment of fecal impaction. However, if conservative measures with digital disimpaction and enemas fail, local anesthesia to relax the anal canal along with abdominal massage may be useful. In rare cases, using a colonoscopy with a snare to fragment the fecal material in the distal colon may be needed. If at any time, abdominal tenderness or bleeding occurs, which may indicate bowel perforation or ischemia, surgery may be necessary.

National Digestive Diseases Information Clearinghouse. Constipation; http://digestive.niddk.nih.gov/ddiseases/pubs/constipation/

National Institute on Aging. AgePage: Concerned About Constipation? http://www.nia.nih.gov/health/publication/concerned-about-constipation

The Rome Foundation. http://romecriteria.org/