D. J. Carmichael1, D. T. Smelser2, D. J. Carey2, R. L. Hoffman1 1Geisinger, General Surgery, Danville, PA, USA 2Geisinger, Genomic Health, Danville, PA, USA
Introduction:
Variation in the incidence of diverticulitis by season has been described. However, the etiology of this is uncertain. Previous work in our group showed worsening disease severity during the winter (off-season). Independent of that, other work in our group has shown an increased frequency of disease recurrence with those with a higher polygenic risk score (PRS). With this in mind, the aim of this study was to evaluate if genetics was a potential contributor to seasonal variation in diverticulitis. We hypothesized that patients with higher PRS scores may present more frequently in the winter (off-season) months.
Methods:
All patients admitted with diverticulitis between 2013-2021 who were also enrolled in the Geisinger MyCode biobanking program were included. All patients were assigned an overall PRS decile, highest representing increased genetic risk of disease. Incidence and outcomes for quarter of the year (Q1=Jan-Mar, Q4=Oct-Dec) and Summer(May-Aug) vs Winter(Nov-Feb) in northeast US were performed with two cohorts: first, between patients from the 0-2nd deciles (low PRS group) and those in the 7-9th deciles (high PRS group); then, those in the 0th decile and those in the 9th decile were also compared. A multivariate analysis was performed to compare the above outcomes between the previously described groups.
Results:
A total of 3,767 patients were included; 3,512 (93.2%) with uncomplicated diverticulitis. The mean age was 61.8 years (SD 14.0), and 2,284 (60.6%) female. The incidence of presentation was slightly higher in Q3 than Q4 (Q1:24.1%, Q2:25.8%, Q3:26.7%, Q4:23.4%), and significantly higher in the Summer (36.4%) vs Winter (30.5%; p<0.001). There were no significant differences in incidence by quarter or Summer/Winter when patients were categorized as PRS 9vs0 or PRS high vs. low. Patients presenting in Q4 (Oct-Dec) with a high PRS were more likely to have complicated disease (12.7%) versus those with a low PRS (2.2%; p=0.008). This difference was not observed in other quarters. There were no significant differences in length of stay by season when taking into account genetic risk. Readmission within 30 days was significantly greater for high PRS patients in Q2 (April-June; 14.6% vs. 7.4% low PRS; p=0.006).
Conclusion:
While there was no significant seasonal variation in incidence according to genetic risk, there were some differences in outcomes related to disease severity. The higher rates of complicated disease in high genetic risk patients in the late Fall quarter and higher rates of readmission in those patients in the early Spring suggests that perhaps genetic risk may surpass environmental risk of disease in the “off” season. These findings generate more fodder for research into the complex interplay between genetics and environment in this disease process.