Original article
Alimentary tract
Long-term Risk of Acute Diverticulitis Among Patients With Incidental Diverticulosis Found During Colonoscopy

https://doi.org/10.1016/j.cgh.2013.06.020Get rights and content

Background & Aims

Colonic diverticulosis is the most common finding during routine colonoscopy, and patients often question the significance of these lesions. Guidelines state that these patients have a 10% to 25% lifetime risk of developing acute diverticulitis. However, this value was determined based on limited data, collected before population-based colonoscopy, so the true number of cases of diverticulosis was not known. We measured the long-term risk of acute diverticulitis among patients with confirmed diverticulosis discovered incidentally on colonoscopy.

Methods

We performed a retrospective study using administrative and clinical data from the Veterans Affairs Greater Los Angeles Healthcare System, collecting data on patients who underwent colonoscopies from January 1996 through January 2011. We identified patients diagnosed with diverticulosis, determined incidence rates per 1000 patient-years, and analyzed a subgroup of patients with rigorously defined events confirmed by imaging or surgery. We used a Cox proportional hazards model to identify factors associated with the development of diverticulitis.

Results

We identified 2222 patients with baseline diverticulosis. Over an 11-year follow-up period, 95 patients developed diverticulitis (4.3%; 6 per 1000 patient-years); of these, 23 met the rigorous definition of diverticulitis (1%; 1.5 per 1000 patient-years). The median time-to-event was 7.1 years. Each additional decade of age at time of diagnosis reduced the risk for diverticulitis by 24% (hazard ratio, 0.76; 95% confidence interval, 0.6–0.9).

Conclusions

Based on a study of the Veterans Affairs Greater Los Angeles Healthcare System, only about 4% of patients with diverticulosis develop acute diverticulitis, contradicting the common belief that diverticulosis has a high rate of progression. We also found that younger patients have a higher risk of diverticulitis, with risk increasing per year of life. These results can help inform patients with diverticulosis about their risk of developing acute diverticulitis.

Section snippets

Data Source

We performed a retrospective survival analysis using administrative and clinical data from the Veteran's Affairs (VA) Greater Los Angeles Healthcare System (VAGLAHS) collected between January 1996 and August 2011. VAGLAHS maintains electronic medical records from 14 community clinics and 1 inpatient academic medical center: the West Los Angeles VA. The VAGLAHS database includes patient demographics, inpatient and outpatient treatment files, and laboratory, imaging, pathology, and pharmacy data.

Patient Characteristics and Descriptive Statistics

Over the 15-year study period, we identified 2222 subjects with chart-confirmed colonic diverticulosis. Table 1 presents the patient characteristics and procedure indications stratified by diverticulitis status. The median follow-up period was 6.75 years (interquartile range, 3.75–9.66 y; maximum, 15 y; minimum, 1 mo; mean ± SD, 6.75 ± 3.6 y).

Incidence Rates of Diverticulitis

We identified 95 patients (4.3%) who developed acute diverticulitis based on any of the defined criteria as discussed earlier, whereas 23 (1%) had

Discussion

The natural history of diverticulosis is poorly understood. Published guidelines and reviews state that 10% to 25% of patients with colonic diverticulosis ultimately will develop diverticulitis over the course of their lifetime.5, 6, 23, 31, 32 However, this widely cited figure is based on data predating population-based screening colonoscopy.5 Therefore, the true denominator of individuals harboring diverticulosis was not accounted for in these calculations.

To calculate the true incidence of

Acknowledgments

This article was presented at the American Gastroenterological Association Distinguished Abstracts Plenary Session at Digestive Disease Week 2012, May 19-22, San Diego, California.

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    The opinions and assertions contained herein are the sole views of the authors and are not to be construed as official or as reflecting the views of the Department of Veteran Affairs.

    Conflicts of interest These authors disclose the following: Brennan Spiegel has served as an advisor for Ironwood Pharmaceuticals and has received research support from Amgen, Ironwood Pharmaceuticals, and Shire Pharmaceuticals; and Linnette Yen, Paul Hodgkins, and M. Haim Erder are employees of Shire Pharmaceuticals. The remaining authors disclose no conflicts.

    Funding This study was supported by a research grant from Shire Development, LLC.

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