This is a retrospective study. The study subjects were selected from patients in the Endoscopic Center of the Gastroenterology Department at Meizhou People’s Hospital to undergo a complete colonoscopy and first-time removal of colorectal polyps at Jan. 2018 to June 2019. Patient was qualified for analysis if meeting the criteria: (1) histologically diagnosed as colorectal polyps; (2) at least one follow-up colonoscopy was performed six months after polyp removal; (3) has sufficient baseline clinical and laboratory data. Patients were excluded if they had present/previous gastrointestinal tumors, cardiac or pulmonary disease. The study was approved by the Ethics Committee of Meizhou People’s Hospital Affiliated to Sun Yat-Sen University.
A total of 3,980 patients took initial colonoscopy and underwent removal of colorectal polyps during this period. 3,207 patients were excluded for absent of follow-up colonoscopy and left 773 patients chosen in our study. Participants were further filtered for lacking pathology reports (n = 80), and/or lipid data (n = 50), or follow-up colonoscopy performed less than 6 months after removal (n = 30). Finally, there were 435 patients going into analysis (Figure 1).
Polyp classification and definition of polyp recurrence
Pathology characteristics of colorectal polyps were obtained from pathology reports. Polyps were classified into hyperplastic polyp, inflammatory polyp, tubular adenoma, tubulovillous adenoma. Advanced polyp was defined if one or more following conditions were met: a tubular adenoma with 10 mm or larger in diameter, tubulovillous adenoma, or the presence of high-grade dysplasia. The location of polyps was divided into proximal (cecum, ascending colon, hepatic flexure, transverse colon, and splenic flexure) and distal (descending colon, sigmoid colon, and rectum). In patients with multiple polyps, histologic type, size and location counted on the largest and/or most advanced adenoma.
Polyp recurrence was defined if any polyp was found in the follow-up colonoscopy performed at least 6 months after initial removal, including both at the same location and other locations.
Clinical characteristics and laboratory results were obtained from medical records when patients underwent polyp removal. Patients were de-identify before analysis to protect privacy. Baseline characteristics including gender, age, body mass index (BMI), drinking history, smoking history, hypertension, diabetes mellitus (DM) were collected. Lipid profiles were serum total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), apoliprotein A1 (ApoA1) and apoliprotein B(ApoB).
Drinking was defined as positive when consuming alcohol more than 30g/day. Hypertension was defined as blood pressure ≥ 130/85 mmHg and/or current use of anti-hypertensive medication. DM was diagnosed if the patient had either fasting blood glucose of ≥126 mg/dl, a random glucose level of ≥200 mg/dl were taking antidiabetic medication. Dyslipidemia was defined as TC ≥5.17 mmol/L, or TG ≥ 1.7 mmol/L, or HDL-C < 1.04 mmol/L, or LDL-C ≥4.14 mmol/L, or taking anti-dyslipidemic medication.
Statistical analyses were performed using SPSS software version 22.0 (SPSS Inc., Armonk, NY). Continuous variables were expressed as mean ± SD. Categorical variables were expressed as proportions. The normality of the distribution of continuous variables was tested using the Kolmogorov-Smirnov test. Continuous variables were tested by Student’s t test, whereas categorical variables were analyzed by Chi-square (χ2) test or Fisher's exact tests. Univariate and multivariate regression was used to estimate odd ratios (ORs) with 95% CIs. All tests were 2-sided, P value < 0.05 was considered statistically significant.