"OFF-SEASON" DIVERTICULITIS AND DISEASE SEVERITY: WORSE IN THE WINTER?
Kristen L. Wahlen*1, Irene Cho2, Kevin Long1, Sasha Slipak1, James Markman1, Joseph Blansfield1, Rebecca L. Hoffman1
1Geisinger Medical Center, Danville, PA; 2Geisinger Commonwealth School of Medicine, Scranton, PA
Introduction:
The incidence of diverticulitis has a well-documented cyclic variation, with the highest incidence in the summer months (quarter 3: July- September). Previous studies have not evaluated the severity of the disease by season. We hypothesize that there may be differences in severity based on the time of year; that perhaps patients presenting in the "off-season" may have more severe disease. The aim of this study was to identify differences in severity of diverticulitis based on the time of year.
Methods: A retrospective cohort study of patients admitted with CT-confirmation of diverticulitis in one health system (2006-2021) was performed. Outcomes reflecting disease severity, including operation within 24 hours of admission, operation during index admission (>24hrs), length of stay, and 30-day readmission were obtained. Univariate and multivariate analyses were performed to compare outcomes based on the admission months according to quarter of the year: Q1 (Jan 1-March 31), Q2 (April 1-June 30), Q3 (July 1-Sept 30), Q4 (Oct 1-Dec 31). A secondary analysis was performed using just admissions in the summer months (May-Aug) vs winter months (Nov-Feb).
Results:
A total of 8,622 patients were included; 55.4% female (n=4,777), 20.5% smokers (1,768), and 92.2% with uncomplicated disease (7,950), with a mean age of 60.6 years (SD15.4). Rates of admission were highest in Q3 (2497, 29.0%), followed by Q2 (2226, 25.8%), Q4 (2077, 24.1%) and Q1 (1822, 21.1%). Although not significant, admissions for complicated diverticulitis were highest in Q1 (165, 9.1%) and lowest in Q3 (171, 6.9 %; p=0.07), rates of emergent operation were highest in Q1 (180, 2.1%) and lowest in Q3 (42, 1.7%), rates of operative intervention during index admission were highest in Q1 (n=30, 1.7) and lowest in Q3 (n=28, 1.1%; p=0.48), and readmission rates were highest in Q1 (n=220, 12.1%) and lowest in Q3 (n=249, 10.0%; p=0.18). On multivariate regression, patients in Q3 had a significantly decreased odds of presenting with complicated disease (OR 0.73, 95%CI0.59-0.92) compared to Q1, a significantly lower risk of emergent operation (OR0.65; 95%CI 0.42-0.98), and a significantly lower rate of 30 day readmission (OR 0.81, 95%CI 0.67-0.98). When just comparing summer to winter, patients in the winter were significantly more likely to require an emergent operation (OR 1.48, 95%CI 1.03-2.14).
Conclusion:
While diverticulitis admissions have a slightly higher incidence in the summer months, the severity of disease is significantly worse in the winter months with regard to complicated disease, needing an emergent operation, or being readmitted within 30 days. This suggests that disease severity overall might be worse for patients presenting in the "off-season," allowing clinicians to better manage expectations and anticipate possible hospital resource utilization.
Table 1: Comparision of Patient Population and Outcomes in the Winter versus Summer Months
Graph 1: Incidence of Disease-Severity Measures by Season
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