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Constipation prevalence (strangers to the lavatory)

Systematic review
Results
Comment

What is common? Apparently, back in 1965 around 99% of factory workers in the UK had a bowel frequency of between three times a week and three times a day (3-21 movements a week), and this has been a rule-of-thumb standard definition. A systematic review of laxative treatments in Bandolier 46 had the number of weekly bowel movements with placebo in the range of 1-7, mostly below five a week, which fits with that. But straining, hard stools, incomplete evacuation and other aspects of impaired defecation are important.

A systematic review of the prevalence of constipation in a North America [1] takes not just definition into account, but also issues around sex, race, age, and other factors, to try and tease apart how these might influence constipation prevalence estimate.

Systematic review

The search was for studies published up to about the end of 2002, and used three electronic databases and manual searches of reference lists. Selection criteria included population-based studies of North American populations, in adults, reporting prevalence of constipation, in full English-language publications.

Definitions of constipation allowed were self-report by subjects, physician or coded diagnosis, or standardised definitions. One, for instance, included 12 weeks or more of the following:

Results

Ten reports were included (USA and Canada), over the years 1964 to 2000. Populations studied ranged from about 700 to nearly 900,000. Self-report of constipation was the most commonly used definition, with self-reported answers to defined questions next most common, with two studies using face-to-face questions as part of a census.

The overall average percentage of people with constipation was about 15% (1 in 7 adults). The range was 1.9% to 27%, shown in Figure 1 according to how constipation was ascertained. Most reports were in the range of 12% to 19%, with some self-reported prevalences being higher, and both face-to-face questioning reports below 4%.



Figure 1: Constipation population prevalence in adults, according to method of ascertainment





There was a distinctly higher prevalence in women compared with men in almost every study, irrespective of method of ascertainment (Figure 2). Prevalence of constipation in women was on average about twice as high as in men. There was also a consistent finding of higher constipation prevalence in non-Caucasian people, by a factor of about 1.4 to 1, though non-white racial groups were not subdivided.



Figure 2: Constipation prevalence in men and women





Other trends were for decreased prevalence in people with highest income and highest educational attainment or years of education, though these may well be measuring different aspects of the same phenomenon. Older age, especially age over 70 years, was also associated with higher constipation rates. Because different age ranges were reported the results were not consistent between studies, but an example from a study using face-to-face questioning is shown in Figure 3.



Figure 3: Constipation by age in one study





Comment

How many adults in industrialised countries have constipation? The answer is about 1 in 7. Though this review looked only for North American studies, the results are probably much the same in any industrialised country with western diets and behaviour patterns. What is interesting is a general consistency of result in terms of overall population, and effects of sex, race, and age, despite studies using different ascertainment methods and criteria, different study size, and sampling over about 35 years.

Constipation is not fun. Diet, especially fibre, and exercise can promote better bowel habit, and perhaps the finding of lower constipation prevalence with income and years of education reflects better adherence to healthy lifestyles by the more educated and better off. Lots of people must spend money on products from the pharmacist, or see their doctor for a prescription for a laxative.

Perhaps constipation avoidance should be yet another topic that goes onto the healthy living list, associated with good diet and moderate exercise. Bandolier will look for more evidence of that.

Reference:

  1. PD Higgins, JF Johanson. Epidemiology of constipation in North America: a systematic review. American Journal of Gastroenterology 2004 99: 750-759.

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