Evidence-Based Reviews

5-step plan to treat constipation in psychiatric patients

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Algorithm can individualize treatment when drugs or other factors are binding.


 

References

Mr. W, age 50, presents to the psychiatry clinic with obsessive-compulsive disorder (OCD) symptoms. At his first interview, he says he spends every waking hour obsessing over whether or not he does things “right.” These thoughts force him to compulsively check and recheck everything he does, from simple body movements to complex computer tasks.

He has a history of OCD since age 8, with intermittent episodes of major depression. He reports that several years ago, he had a “miraculous” response to clomipramine for several weeks but has not responded to any other medication. Nevertheless, he continues taking clomipramine, 50 mg/d, hoping that it “might eventually do some good.” He adds that when he tried to increase the dose, he suffered from “terrible constipation” despite regular use of a methylcellulose fiber supplement.

The psychiatrist discontinues clomipramine and starts Mr. W on duloxetine, 90 mg/d. At the next visit, Mr. W complains that his constipation is much worse, so the psychiatrist decreases duloxetine to 60 mg/d, which eventually provides some relief. Because Mr. W has minimal response to duloxetine after 6 months, the psychiatrist adds olanzapine. Although this agent is anticholinergic, the patient had responded to a previous trial of this antipsychotic. Soon after, Mr. W experiences severe constipation.

Psychiatric patients face a host of potential causes of constipation, including:

  • use of psychotropics and other medications
  • decreased eating or physical activity as a result of depression or another psychiatric disorder
  • medical comorbidities that decrease gastrointestinal (GI) motility.

Constipation carries a tremendous cost in terms of resources and quality of life.1-7 This condition also can make patients stop taking medications. You can help patients avoid the discomfort and quality-of-life consequences by promptly diagnosing constipation and following a 5-step treatment algorithm that has shown value in our clinical practice.

Box 1

Diagnostic criteria for functional constipation
  1. 2 or more of the following
  2. Loose stools are rarely present unless the patient takes a laxative
  3. Patient does not meet criteria for irritable bowel syndrome

* Must be present during ≥25% of defecations
Source: Reference 8

What to look for

When evaluating a patient who complains of constipation, first determine what he or she means by “constipation.” Do not rely on frequency of bowel movements as the only criterion for diagnosis. Under Rome Committee for Functional Gastrointestinal Disorders guidelines for diagnosis of chronic (or functional) constipation, patients who move their bowels daily may meet criteria for chronic constipation if they experience straining, incomplete evacuation, or other symptoms (Box 1).8

Many patients who complain of constipation have daily, regular bowel movements that produce hard, difficult-to-pass stool or require straining or manual maneuvers. Take a careful history including:

  • stool frequency and quality
  • straining
  • manual maneuvers (disimpaction or manual pelvic floor support)
  • sensation of blockage or incomplete evacuation.
In women, take a history of childbirth and obstetric or gynecologic surgery. Also determine the timing of symptom onset related to any new prescription or over-the-counter medications or supplements.
‘Alarm’ symptoms. For psychiatrists, the most important part of the Rome guidelines are the “alarm” symptoms:
  • age ≥50 years
  • family history of colon cancer or polyps
  • family history of inflammatory bowel disease (ulcerative colitis or Crohn’s disease)
  • rectal bleeding, anemia
  • weight loss >10 pounds
  • new onset of chronic constipation without apparent cause in an elderly patient
  • severe, persistent constipation refractory to conservative management.9
Refer a patient with any of these symptoms to a specialist for endoscopic or clinical evaluation. Follow United States Preventative Services Task Force recommendations for colorectal cancer screening of all patients age ≥50 (Table 1).10

Table 1

Colorectal cancer screening recommendations*

TestFrequency
Fecal occult blood testing (FOBT)Annually
SigmoidoscopyEvery 5 years
FOBT and sigmoidoscopyEvery 5 years
Double contrast barium enemaEvery 5 years
ColonoscopyEvery 10 years
* For patients age=50. For higher-risk patients, it is reasonable to begin screening at a younger age
Source: Reference 10

Determining the cause

Common causes of constipation include altered visceral sensitivity, decreased GI motility, alterations in pelvic and anorectal musculature, and alterations in the enteric nervous system. Systemic causes are less common and include electrolyte abnormalities (hypercalcemia and hypokalemia) and endocrine disorders (hypothyroidism and diabetes mellitus).

Some patients’ constipation is caused by involuntarily contracting the pelvic floor muscles or suppressing the urge to defecate (Box 2).1,11,12 Suspect this in patients who strain repeatedly to pass soft or liquid stool.

Medication side effects are probably the most common constipation cause psychiatrists will encounter. Many psychotropics have anticholinergic effects that decrease GI motility and cause constipation. The most commonly implicated drugs are:

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