Epidemiology
The prevalence of diverticular disease increases with age, being <10% in those younger than 40 years of age, approximately 50% at 50 years of age, and 50% to 66% at over 80 years of age in developed countries.[11][12] However, while more common in older people, it is increasingly occurring in younger age groups; the incidence of diverticulitis in patients aged 40 to 49 years increased by 137% between 1980 and 2007.[12]
There is geographical variation in the prevalence of diverticular disease. One study reported diverticular disease prevalence of 2.5% to 51.4% in Europe.[13] Although earlier studies describe diverticular disease as being rare in rural Africa and Asia (with highest prevalence in the US, Europe, and Australia), data indicate an overall increased prevalence in these regions.[13]
Vegetarians have been shown to have a lower incidence of diverticular disease.[14][15][16] Right-sided diverticular disease, which is more common in Asia and specifically in younger people in Asia, is shown to be associated with meat consumption in Asian populations.[7][8][10]
The prevalence of diverticular disease in men is approximately equal to that of women. However, in a recent study from the US, diverticulosis was less prevalent in women compared with men in the same age groups, indicating that sex hormones might affect pathogenesis.[17] Another study reported that diverticular bleeding occurs more commonly in men, and strictures and obstructions due to diverticulitis occur more often in women.[18]
Rarely, a more aggressive form of diverticular disease manifests in younger obese males (<40 years of age).[19]
Risk factors
This is the strongest risk factor. Incidence of diverticular disease increases in older people, and it is extremely rare in children.[11] This may be due to decreasing mechanical strength of the colonic walls. Changes in collagen structure may cause age-associated decreases in the colonic wall strength.[34]
Low-fibre consumption results in low stool weight and increased transit time, which in turn results in increased segmental pressure in the colon leading to diverticula formation.[31][32] High-fibre intake may reduce the risk of diverticular disease (intake more than 30 g/day) compared with people with low-fibre intake.[21][35]
Obesity is a predisposing factor.[22]
Modest increases in body mass index (BMI) may increase the risk of diverticular disease, as well as the risk of diverticular disease complications.[23] Complications of diverticular disease, such as perforations and recurrent diverticulitis, are more common in people with a BMI greater than 30, and these people are also at increased risk of diverticular bleeding.[35][36][37]
Several studies, including a meta-analysis, have suggested an increased risk of colonic diverticulosis among current smokers compared with non-smokers.[25]
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