Spotlight: constipation in the older patient

Constipation is a widespread problem in the older population that can significantly affect patients’ quality of life.^1-3 It is typically characterised by reduced stool frequency and/or difficulty passing stool.^1-5 Estimates regarding prevalence vary, but it appears that around 20% of patients over the age of 65 suffer from constipation,^1-4 with this figure rising to 30% amongst those older than 85 years old (and up to 80% in nursing home residents).^1,3,5-9

A recent American study found that between 1997 and 2010, the number of patients being discharged with a primary or secondary diagnosis of constipation has quadrupled, with a similar rise in the cost of inpatient treatment.⁴ However, despite the high prevalence and significant complications caused by constipation, it is often underdiagnosed and undertreated in older patients, and there are significant gaps in the literature regarding which treatments are most effective in the elderly. This article summarises the approach to dealing with older patients suffering from constipation and the evidence behind commonly prescribed treatments.

Defecation

Normal defecation involves a number of actions, and understanding the sequence of events can help target therapy when treating constipation.^7,9 Stool is propelled through the colon by peristalsis. Normal defecation begins when the cerebral cortex becomes aware of rectal filling and the patient adopts a sitting/squatting position. The puborectalis muscle then relaxes, the pelvic floor descends and the anorectal angle straightens. Colonic peristalsis is inhibited and the abdominal wall contracts to raise intrabdominal pressure. The external anal sphincter then relaxes allowing faeces to be expelled.

Defining constipation

Constipation can be defined as unsatisfactory defecation due to a reduction in stool frequency and/or difficult stool passage. Symptoms vary between patients, although many are included in the Rome III criteria (Box 1). A diagnosis of chronic constipation can be made if at least two of these criteria are met for at least three months (with symptom onset at least six months prior to diagnosis).¹

 

Causes of constipation

Constipation can be subdivided into primary constipation (caused by primary bowel disorders) and secondary constipation (caused by systemic factors).

Primary constipation can be further subdivided into slow-transit constipation, defecation disorders and constipation-predominant irritable bowel syndrome. Constipation-predominant IBS will not be discussed in detail within this article, but is characterised by symptomatic relief post-defecation.

Slow-transit constipation is where there is primary dysfunction affecting the bowel smooth muscle and/or its innervation. In the elderly population, this may be caused by neuronal loss and impaired response to stimulation (myenteric dysfunction), reduced inhibitory nerve input, collagen deposition within the bowel and reduced endorphin binding to intestinal receptors.

Defecation disorders encompass conditions where there are failures to coordinate abdominal and pelvic muscles, impaired perineal descent or structural abnormalities. In older patients, causes include reduced muscle mass and squeeze pressure, pelvic floor dysfunction (particularly in post-partum women) and painful anorectal conditions (haemorrhoids, anal fissures, fistulae, prolapse etc).⁹

Some secondary causes of constipation are listed in Box 2.

 

Complications of constipation

Untreated constipation can lead to faecal impaction, where hard stool accumulates in the rectum and cannot be passed easily.⁶  This may lead to overflow incontinence, and hence skin breakdown and social isolation.^3,7 Over 50% of older patients presenting with “diarrhoea,” are subsequently diagnosed with faecal impaction, which is also a common cause of urinary retention.⁶ Impacted faeces can also compress on the bowel wall lading to ischaemic ulceration (stercoral ulceration).⁵ Less commonly, volvulus or perforation can also occur.⁷ In addition, excessive straining makes anal fissuring five times more likely, doubles the risk of rectal prolapse (as well as increasing the risk of uterine, bladder and vaginal prolapse) and quadruples the risk of haemorrhoids.^1,7

Assessment of constipated patients

As with any patient, a detailed history should be taken, including screening patients for alarm features (Box 3). Other relevant parts of the history include symptom duration, stool frequency, the patient’s definition of constipation (straining being far more common than reduced stool frequency¹), symptoms suggestive of IBS (pain, bloating, malaise etc), drug history, laxative usage and lifestyle factors (including dietary fibre, fluid intake and physical activity).

 

 

Important features in the physical examination include looking for surgical scars, abdominal distension, palpable faeces and the character of the patient’s bowel sounds. Rectal examination is essential to check for faecal impaction, as well as rectal masses and complications like haemorrhoids and anal fissures.

The American College of Gastroenterology Chronic Constipation Taskforce does not advocate the use of multiple investigations in constipated patients.¹¹ Despite this, basic blood tests may be indicated in older patients (full blood count, haematinics, electrolytes, bone profile, blood glucose and thyroid function), as well as colonoscopy or virtual colonoscopy in patients with alarm symptoms.⁷

Colonic transit time studies and anal manometry may be performed in selected cases, although both tests have their limitations. The first of these techniques involves administrating radiopaque markers and monitoring their passage through the bowel on serial abdominal X-rays.^2,9 The test is relatively inexpensive, but technically measures oro-anal rather than colonic transit, and findings have not been found to be reproducible. Anal manometry can be used to assess neuromuscular coordination and power, and can be combined with a balloon expulsion test (expulsion of a 50ml balloon within one minute).^2,7. These tests are not standardised however, and the latter test requires the patient to lie in the left-lateral position, so does not accurately reflect normal defecation.

Non-pharmacological treatments of constipation

Constipated patients are often advised to make lifestyle modifications, although the evidence behind these recommendations is variable.^2,5 It is often recommended that patients should have 20-35g of dietary fibre per day, and although one cohort study showed improvement in self-reported constipation,⁷ a systematic review of 264 patients in 8 small studies showed inconsistent results.¹²

There are some cohort studies (one of which monitored over 21 000 nursing home residents) that show a link between reduced fluid intake and constipation,⁷ but no randomised controlled trials have shown that increased fluid intake reduces the incidence of constipation.^5,7. There is a similar lack of good-quality trial evidence to prove the beneficial effect of exercise on constipation symptoms, with two RCTs (246 older patients) showing no improvement in bowel symptoms, although some cohort studies have shown a reduction in symptoms with exercise.^7,12 However, increasing fluid intake, dietary fibre and exercise has not been shown to result in harm, and may be beneficial in appropriate cases.

A newer technique that has proven efficacy is biofeedback training, which is of benefit in patients with dyssynergic defecation, where there is impaired coordination between pelvic floor muscle relaxation and abdominal wall effort during defecation.⁷ This technique involves inserting a rectal catheter, so that the sphincter muscles straddle four sensors, and a balloon is then inflated to allow measurement of abdominal effort. The patient is then taught breathing techniques to increase abdominal push effort and synchronise it with anal relaxation.⁹

Sessions typically happen on a weekly basis for a six-week period. Although there is proven efficacy when compared to sham, placebo and certain laxatives, biofeedback training is not widely available and is not likely to be well-tolerated by frail elderly patients (only one small trial has specifically looked into efficacy in the older population).^5,9,13

Other techniques for refractory constipation include sacral neuromodulation and subtotal colectomy, although there is limited evidence of their efficacy, and in addition, many elderly patients would not be good candidates for surgical intervention.^2,7

Pharmacological treatments of constipation

Laxative prescription in the elderly should ideally be targeted to address patients’ specific problems (i.e. using bulking agents in patients with low fibre intake, stool softeners for hard stool, stimulants for patients with reduced mobility etc).² Laxative prescription is widespread in the elderly, with one recent study of nursing home residents showing that 50-74% of patients require laxatives on a daily basis.^1,6

Fibre/bulking agents

Bulking agents are organic polymers, which work by increasing water adsorbence, and as a result, stool bulk and consistency is improved. Examples include bran, psyllium (isphagua husk), methylcellulose and calcium carbophil. Side-effects include flatulence (due to fermentation by bowel flora), bloating and bowel obstruction (rarely),^5,10 There is some moderate quality evidence for the use of psyllium,^2,5,7 but overall, there is little evidence supporting the use of this drug class in constipated patients.⁵

Stool softeners

Stool softeners work as detergents, leading to increased interaction between water and solid stool. Examples include sodium docusate and diodyl sodium sulfosuccinate. There is very little trial evidence to support the use of stool softeners in the elderly,^1,2,14, with only one small trial from 1968 showing efficacy over placebo, and this was not replicated in later studie.⁵ Additionally, a trial has indicated that in non-elderly patients, sodium docusate is inferior to bulking agents.^7,15 Despite this, sodium docusate remains widely prescribed in older patients.

Stimulants

Stimulant laxatives work by stimulating the myenteric plexus and inhibiting reabsorption of water.⁷ Examples include senna, sodium picosulfate and bisacodyl. There is some evidence that all of these drugs are more effective than placebo, and four trials have shown superiority of senna/bisacodyl over other laxatives.^1,5,7,15 For example, a senna-fibre combination was compared to lactulose in two trials.^7,18 Both studies found that in older patients, there was in improvement in stool frequency and consistency. Potential side-effects include abdominal cramps, protein-losing enteropathies and electrolyte disturbances.^5,10 Stimulants should also be avoided in younger patients, as they can trigger denervation of the gut.

Osmotic laxatives and constipation

Osmotic laxatives contain molecules that are poorly-absorbed from the bowel, and thus increase luminal water content through osmosis. Examples include lactulose, milk of magnesia and polyethylene glycol (PEG- the active ingredient of Movicol/Laxido). There is moderate trial evidence supporting the use of lactulose, with multiple RCTs showing superiority over placebo.^2,5,7,14,19 For example, in a double-blind trial of lactulose in 47 older patients, patients in the treatment arm had significantly increased stool frequency and a significantly lower incidence of faecal impaction. There is also good trial evidence for the use of PEG,^{2,5,7,9,20-22} with several trials showing efficacy over placebo (including in subgroup analysis of elderly patients) and other laxatives including lactulose (with meta-analysis of RCTs involving roughly 200 patients showing superiority in terms of stool frequency & consistency).^14,20,22,23 Potential side-effects include diarrhoea, flatulence and nausea.^1,5,10,21

Enemas and suppositories

Although both of these are widely used in clinical practice, there have been few trials to demonstrate their efficacy. One small trial investigated the use of regular enemas compared to lactulose in 123 elderly patients.⁵ It was found that there was no noticeable difference in the treatment groups in terms of reducing incidence of overflow diarrhoea. However, anecdotally, enemas and suppositories are considered highly effective treatments for acute constipation (especially in elderly patients with reduced anal sphincter tone).

Linaclotide is a guanylate cyclase agonist, which works by increasing luminal chloride & bicarbonate, and thus stool fluid content.⁷ Three RCTs involving over 1500 patients have shown that linaclotide improves stool consistency and straining symptoms, with the NNT being approximately 6.^1,5 The drug is tolerated well, but dose-dependent diarrhoea may occur.

A newer drug is prucalopride, which is a 5-HT4 receptor agonist. It is supported by data from three double-blinded placebo-controlled trials,²⁴ with over 300 patients in the elderly subgroup. In older patients, it was found that there was a significant increase in stool frequency when compared to placebo, and this efficacy was maintained when drugs were used long-term (over two years).^9,25 Prucalopride is also well-tolerated, but may trigger headache, nausea and diarrhoea.^24,25

Summary

Constipation is a problem that is highly prevalent in the older population, and can present with a variety of symptoms. Thorough history and clinical examination is often all that is needed following presentation, although patients should be referred for further investigations to rule out treatable secondary causes or malignancy.

Having determined the likely cause(s), therapies should ideally be individualised to correct the underlying problem. There is little evidence to support lifestyle modifications in the elderly, although these have not been shown to be harmful, and may be beneficial in selected cases. Overall, there are few large, well-designed trials to help guide optimal pharmacological management of elderly patients.^5,12. However, certain commonly prescribed laxatives have been shown to be effective at improving constipation symptoms, with good evidence for the use of laxatives like senna, lactulose and PEG (which can also be used in combination), although other widely-used laxatives like sodium docusate have not been proven to be effective in clinical trials.

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Dr Gemunu Cooray, Consultant Geriatrician, Watford General Hospital

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Article first published in 2015; updated 2024. A section on lubiprostone for people with chronic constipation has been removed as the product has been discontinued. 

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