Subjects
From January 2009 to December 2011, consecutive asymptomatic subjects aged ≥ 20 years old undergoing a colonoscopy during a health check-up were included into this study. The subjects were excluded if they reported symptoms of lower gastrointestinal tract disease including rectal bleeding, a marked change in bowel habits, or lower abdominal pain that would normally require medical evaluation. Other exclusion criteria were a history of colitis, colorectal polyps or colorectal cancer, prior colonic surgery, undergoing a sigmoidscopy, a colonoscopy, or a barium enema within the previous 10 years. The study protocol was approved by Institutional Review Board at Kaohsiung Veterans General Hospital and all participants provided written informed consent.
Study design
A complete history and physical examination were performed for each subject undergoing the health check-up. All subjects were carefully queried regarding the presence of abdominal symptoms in the previous 1 month. Subjects who responded negatively were classified as asymptomatic subjects and were enrolled into this study. All the participants received anthropometric and blood biochemical tests including fasting plasma glucose, serum triglyceride and high-density lipoprotein (HDL)–cholesterol level, and underwent total colonoscopy. Colonoscopies were performed by three experienced endoscopists (King TM, Wang JH, and Hsu CW) using the Olympus PCF-Q240AL and PCF-Q260AL endoscopy (Olympus Corp., Tokyo, Japan) after the subjects had fasted overnight. Bowel preparation was performed with oral saline lexative following the protocol of diagnostic colonoscopy. The patients were carefully examined for colorectal mucosal lesion. If colorectal diverticula were observed, their location and type was recorded carefully. Distribution type was defined as the following: right-side colon, involving the cecum, ascending colon, or transverse colon; left- side colon, involving the splenic flexure, descending colon, sigmoid colon, or rectum; or bilateral, involving the entire colon. Colorectal polyp was defined as a protuberance into the lumen from the normally flat colonic mucosa. All visible polyps were removed and examined histologically by the pathologist. The pathology types of colorectal polyps were subsequently categorized into hyperplastic polyps and adenomatous polyps.
To assess the relationship between clinical characteristics and asymptomatic colorectal diverticulosis, the following data were recorded for each subject: age; gender; educational status; consumption of tobacco, alcohol, coffee, tea, spicy foods or betel nut, exercise habit, whether vegetarian or not and long-term use of non-steroidal anti-inflammatory drug (NSAID). All variables were categorized for data analyses.
Statistical analysis
The chi-square test or Fisher’s exact test was employed to investigate the relationship between the rate of colorectal diverticulosis and clinical characteristics. These variables included the following: gender; age (<39, 40–49, 50–59, 60–69 or >70 years); education status (<10, 10–12, or >12 years); BMI (<25, 25–30, or >30); regular NSAID use at least 1 year (yes or no); colorectal polyps (hyperplastic polyps or adenomatous polyps); smoking status (no, former smoking, current smoking); consumption of alcohol ,coffee, tea or spicy foods and exercise habit (no, ≤ 3 times per week, or >3 times per week); betel nut habit and vegetarian (yes or no). Metabolic syndrome was defined according to the modified National Cholesterol Education Program Adult Treatment Panel III definition for South Asians and Chinese. A p value less than 0.05 was considered significant. Significant variables revealed by univariate analysis were subsequently assessed by a stepwise logistic regression method to identify independent clinical factors predicting the presence of colorectal diverticulosis. All statistical analyses were performed using SPSS version 17.0 (SPSS Inc. Chicago, II, USA ).