A Matched Case-Control Study Using the Propensity Score on Differences in the Characteristics of Colorectal Polyps between Younger and Older Koreans: Proximal Shift in the Distribution of Colorectal Polyps among Older Koreans

ABSTRACT

BACKGROUND/AIMS: Several studies have found that the frequency of colorectal polyps increases significantly from the age of 50 years. The goal of this study was to determine the differences in the clinical characteristics of colorectal polyps between patients aged 50 years and older, and younger patients. METHODS: The colonoscopy database of 3,304 patients at the Yeungnam University Medical Center between January 2009 and December 2009 was reviewed retrospectively. In total, 679 patients were divided into the younger group (n=170) and the older group (aged > or =50 years) (n=509). A matched case-control study was performed using propensity scores and 117 patients selected from each group. RESULTS: Compared to the younger group, the older group had a significantly higher proportion of female patients, and patients with hypertension, a smoking history, and a history of taking medications. After performing the matched case-control study, 234 patients and 679 colon polyps were included in the analysis. Compared to the younger patients, the older patients had a significantly higher proportion of multiple lesions (57.3% vs 25.6%, p<0.001), left- and right-side distribution (35.9% vs 12.0%, p<0.001), and larger polyps (mean 9.1 mm vs 6.3 mm, p<0.001). A left-sided distribution was less common in the older group than in the younger group (35.0% vs 51.3%, p=0.025). CONCLUSIONS: The methods used to screen for colorectal cancer in older patients should include colonoscopy due to the shift to the right side as a common location for colorectal polyps in that age group.