Association between colonic polyps and diverticular disease

Abstract

AIM: To evaluate the association between colonic polyps and diverticular disease in Japan.

METHODS: We retrospectively reviewed the medical records of 672 consecutive patients who underwent total colonoscopy between August 2006 and April 2007 at Nishinjo Hospital, Okinawa, Japan. Patients with a history of any of the following were excluded from the study: previous polypectomy, colonic resection, and inflammatory bowel diseases. The association between colonic polyps and diverticular disease was analyzed by logistic regression analysis, adjusted for age and sex.

RESULTS: Prevalence of colonic polyps in all patients with diverticular disease was significantly higher than that in those without diverticular disease (adjusted odds ratio 1.7).

CONCLUSION: Our data showed that patients with diverticular disease have a higher risk of colonic polyps compared to those without.

Key Words: Colonic polyps; Colonic neoplasm; Diverticular disease; Proximal diverticular disease; Colono-scopy

INTRODUCTION

The prevalence of colonic neoplasia and diverticular disease has increased in recent years[1–5]. Both have common risk factors such as age and a lack of dietary fiber[6–10]. Despite common epidemiological trends and risk factors, any association between these diseases has not been clarified. Although some data have been reported regarding the association between these diseases in Western countries[11–14], there has been no study in Japan. There are differences between diverticular disease in Western countries and that seen in Asia, including Japan[15–19]. Diverticular disease of the right colon is rare in Western countries[20–22], whereas in Asia, diverticular disease of the right colon is common and has been increasing in recent years[23–27].

This study evaluated the association between colonic polyps and diverticular disease in Japanese patients undergoing total colonoscopy.

MATERIALS AND METHODS

We retrospectively reviewed the medical records of consecutive patients who underwent total colonoscopy between August 2006 and April 2007 at Nishinjo Hospital, Okinawa, Japan. The major indications for total colonoscopy were screening examination after hemorrhoidectomy and rectal bleeding. Patients with a history of any of the following were excluded from this study: Previous polypectomy, colonic resection, and inflammatory bowel diseases. The location of diverticula and polyps was classified into three groups: Distal, proximal and bilateral colon. The borderline between the distal and proximal colon was set at the splenic flexure. Diverticular disease was defined as the presence of one or more diverticula, and all polyps were diagnosed as adenoma by histological examination.

Statistical analysis

The chi-square test was used to compare sex and prevalence of colonic polyps, and the t test to compare mean age. Logistic regression analysis was used to examine the association between diverticular disease and colonic polyps, adjusting for age and sex. P < 0.05 was considered statistically significant. All statistical analyses were performed with SPSS 15.0 for Windows.

RESULTS

The present study included 672 consecutive patients. Of these, 165 (24.5%) had diverticular disease and 189 (28.1%) had colonic polyps. The most common segment for diverticular disease was the proximal, followed by the bilateral and distal colon. The most common segment for colonic polyps was the distal, followed by the proximal and bilateral colon (Table 1). Among patients with diverticular disease, none had active segmental colitis.

Table 1 Number of patients with diverticular disease and colonic polyps by colon segment n (%).

Colon segment	Patients with diverticular disease (%)	Patients with polyps (%)
Distal colon	20 (3.0)	89 (13.2)
Proximal colon	98 (14.6)	53 (7.9)
Bilateral colon	47 (7.0)	47 (7.0)
Total	165 (24.5)	189 (28.1)

Table 2 summarizes the demographic features of patients with or without diverticular disease. The mean age of patients with diverticular disease was significantly higher than that of patients without diverticular disease (P < 0.001). There were significantly more males in those patients with diverticular disease than those without (P = 0.008). The prevalence of colonic polyps in patients with or without diverticular disease was significantly different at 43% and 23.2%, respectively.

Table 2 Comparison of demographic features between patients with or without diverticular disease.

	Patients with diverticular disease	Patients without diverticular disease
No. of patients	165	508
Mean age (SD)	58.0 (13.6)b	47.3 (14.7)
Sex (female: male)	52:113d	219:289
No. of patients with polyps (%)	71 (43.0)d	118 (23.2)

^bP < 0.01 vs without diverticular disease using the t test;

^dP < 0.01 vs without diverticular disease using the chi-square analysis.

Using logistic regression analysis adjusted for age and sex, we calculated the adjusted odds ratio (OR) for colonic polyps (Table 3). This confirmed that the prevalence of colonic polyps in all patients with diverticular disease or those with diverticular disease in the proximal colon was significantly higher than that in patients without diverticular disease (adjusted OR 1.7 and 1.9, respectively).

Table 3 Association between colonic polyps and diverticular disease adjusted for age and sex by logistic regression analysis.

Segment with diverticular disease	No. of patients with polyps /No. of patients with diverticular disease (%)	OR	95% CI	P values
Distal colon	11/20 (55.0)	2.3	0.9-5.8	0.09
Proximal colon	41/98 (41.8)	1.9	1.2-3.0	0.01
Bilateral colon	19/47 (40.4)	1.2	0.6-2.3	0.60
Total	71/165 (43.0)	1.7	1.1-2.5	0.01

DISCUSSION

Colonic neoplasia and diverticular disease have common epidemiological trends and risk factors such as age and a lack of dietary fiber[67]. However, little is known about any association between these diseases. Morini and others found an increased risk for sigmoid colon adenoma in Italian patients with diverticular disease, in a prospective study[28]. Kieff and others have reported an increased risk for distal neoplasia in women in the USA with extensive distal diverticulosis, in a cross-sectional study[29]. Although the sample size and distribution of patients included in the present study might inadequately reflect the general population of Japan, our data showed a 1.7-fold increased risk for colonic polyps in patients with diverticular disease, as compared to those without. In addition, although the prevalence of colonic polyps in patients with diverticular disease in the proximal colon and that in patients without was significantly different, the prevalence of colonic polyps in patients with diverticular disease in the distal or bilateral colon and that in patients without diverticular disease was not significantly different. This observation may be the result of the limited number of patients with diverticular disease in the distal and bilateral colon. However, this result was similar to a previous study in Korea, in which patients with proximal diverticular disease had a higher risk of any proximal neoplasia than did other patients[30]. Diverticular disease of the proximal colon is rare in Western countries, whereas in Asia including Japan, diverticular disease of the proximal colon is relatively common[16172324]. These results suggest that, regardless of the segment with diverticular disease or race, patients with diverticular disease have a higher risk of colonic neoplasia.

In conclusion, our data showed patients with diverticular disease have a higher risk of colonic polyps compared to those without (OR 1.7). This finding needs to be taken into account in surveillance for colonic neoplasia. However, further research is needed to clarify the mechanism of the association between these diseases.

COMMENTS

Background

Prevalences of colonic neoplasia and diverticular disease have increased in recent years. Both colonic neoplasia and diverticular disease have common risk factors such as age and a lack of dietary fiber. Despite common epidemiological trends and risk factors, any association between these diseases has not been clarified.

Research frontiers

There is an increasing body of epidemiological evidence regarding an association between diverticular disease and colonic polyps.

Innovations and breakthroughs

This study clarified the strong association between diverticular disease and colonic polyps. Moreover, this study suggested that regardless of the segment with diverticular disease or race, patients with diverticular disease have a higher risk of colonic neoplasia.

Applications

These results need to be taken into account in surveillance for colonic neoplasia.

Peer review

It is interesting that in the authors’ series there were similar associations between left and right sided diverticulosis and polyps.