Constipation disproportionately affects older adults, with a prevalences of 50% in community-dwelling elderly and 74% in nursing-home residents. Loss of mobility, medications, underlying diseases, impaired anorectal sensation, and ignoring calls to defecate are as important as dyssynergic defecation or irritable bowel syndrome in causing constipation. Detailed medical history on medications and co-morbid problems, and meticulous digital rectal examination may help identify causes of constipation. Likewise, blood tests and colonoscopy may identify organic causes such as colon cancer. Physiological tests such as colonic transit study with radio-opaque markers or wireless motility capsule, anorectal manometry, and balloon expulsion tests can identify disorders of colonic and anorectal function. However, in the elderly, there is usually more than one mechanism, requiring an individualized but multifactorial treatment approach. The management of constipation continues to evolve. Although osmotic laxatives such as polyethylene glycol remain mainstay, several new agents that target different mechanisms appear promising such as chloride-channel activator (lubiprostone), guanylate cyclase agonist (linaclotide), 5HT4 agonist (prucalopride), and peripherally acting µ-opioid receptor antagonists (alvimopan and methylnaltrexone) for opioid-induced constipation. Biofeedback therapy is efficacious for treating dyssynergic defecation and fecal impaction with soiling. However, data on efficacy and safety of drugs in elderly are limited and urgently needed.
The management of constipation in the elderly is challenging both for patients and healthcare providers. Multiple reasons contribute to this phenomenon, such as the effects of aging on gut physiology, co-morbid illnesses, medications, loss of mobility, inadequate caloric intake, and anorectal sensory changes. Elderly patients, especially those with advanced dementia in nursing homes and those on opioids for palliative care, require an individualized approach for the treatment of constipation.
Definition and epidemiology
Constipation is not a well defined disease entity, but a general term used to describe the difficulties that a subject experiences with moving their bowels.1 Healthcare providers typically define constipation as stool frequency of less than 3 bowel movements per week.2 In contrast, patients define constipation as any form of “difficult defecation”, such as straining, hard stool, feeling of incomplete evacuation, and nonproductive urge.3,4 Compared to younger patients, the elderly report more frequent straining, self-digitation, and feelings of anal blockage.4,5 In a study of 531 patients in general practice, 50% gave a different definition of constipation compared to their physicians.6 Because of these variable definitions of constipation, an international panel of experts proposed the Rome criteria for constipation. The Rome III criteria used a combination of subjective symptoms to define constipation,7 and are currently used widely for performing clinical research in this field.
It is reported that the prevalence of constipation increases with age, especially those over the age of 65 years.8 In elderly patients living in the community, the prevalence of constipation is 50%.4 This number is even higher in nursing home residents, with 74% using daily laxatives.4,9–11 Likewise, elderly women are 2 to 3 times more likely to report constipation than their male counterparts.4 Constipation is also more commonly seen in patients taking multiple medications.12
Health-related quality of life and constipation
Evidence in both disease-specific and generic quality of life (QOL) instruments has shown that constipation is associated with impaired health-related quality of life (HR-QOL). For example, in one study of 126 community-dwelling older adults, respondents with chronic constipation had lower Short-Form 36 (SF-36) scores for physical functioning, mental health, general health perception, and bodily pain when compared to respondents with no constipation.13 Likewise, using the Psychological General Well-Being (PGWB) index, 84 subjects with constipation has lower PGWB total scores and lower domain scores for anxiety, depression, well-being, self-control and general health subscales, indicating worse HR-QOL.14 Furthermore, improvements with HR-QOL were noted with treatment of constipation.15 After laxatives caused significant increases in weekly bowel movements, patients reported fewer urinary symptoms, better sexual function and improved mood and depression.
In addition, constipation is a significant driver of health care costs, as it is ranked among the top 5 most common physician diagnosis for gastrointestinal outpatient visits.4 Using a community survey, the management of constipation is estimated to average $200 per patient within a large HMO.16 Over $821 million dollars (2000 value) was spent on over-the-counter laxatives in the United States alone.8 Other indirect costs of constipation to society include decrease in work related productivity, absences in school, lower quality of life and higher psychological distress.
Normal continence and defecation
The pelvic floor consists of superficial and deep muscle layers that envelope the rectum, bladder and uterus.17 The superficial muscle layers consist of the internal and external anal sphincters, the perineal body and the transverse perinei muscles. In contrast, the deep pelvic muscles (also known as levator ani) are composed of the pubococcygeus, ileococcygeus and puborectalis muscles.17 These structures are largely innervated by the sacral nerve roots (S2 –S4 ) and the pudendal nerve.
Continence is the ability to retain feces until it is socially conducive to defecate, while defecation is the evacuation of fecal material from the colon. Both functions are regulated by voluntary and involuntary reflex mechanisms, anatomic factors, rectal sensation, and rectal compliance.
Defecation starts when the cerebral cortex receives an awareness and perception of critical level of filling in the rectum. When the individual adopts a sitting or squatting position, the anal sphincters and the puborectalis relax, straightening the anorectal angle. Simultaneously, the voluntary efforts of bearing down increases the intra-abdominal pressure, facilitating the development of a stripping wave, resulting in stool evacuation.