Visceral Obesity as a Risk Factor for Left-Sided Diverticulitis in Japan: A Multicenter Retrospective Study

BACKGROUND/AIMS Left-sided diverticulitis is increasing in Japan, and many studies report that left-sided diverticulitis is more likely to be severe. Therefore, it is important to identify the features and risk factors for left-sided diverticulitis. We hypothesized that left-sided diverticulitis in Japan is related to obesity and conducted a study of the features and risk factors for this disorder in Japan. METHODS Right-sided diverticulitis and left-sided diverticulitis patients (total of 215) were compared with respect to background, particularly obesity-related factors to identify risk factors for diverticulitis. RESULTS There were 166 (77.2%) right-sided diverticulitis patients and 49 (22.8%) left-sided diverticulitis patients. The proportions of obese patients (body mass index ≥25 kg/m(2), p=0.0349), viscerally obese patients (visceral fat area ≥100 cm(2), p=0.0019), patients of mean age (p=0.0003), and elderly patients (age ≥65 years, p=0.0177) were significantly higher in the left-sided-diverticulitis group than in the right-sided-diverticulitis group. The proportion of viscerally obese patients was significantly higher in the left-sided-diverticulitis group than in the left-sided-diverticulosis group (p=0.0390). CONCLUSIONS This study showed that obesity, particularly visceral obesity, was a risk factor for left-sided diverticulitis in Japan.