S207 There is No Difference in Frequency or Outcome of Colon Ischemia Based Upon the Season of Presentation

Introduction: Colon Ischemia (CI) is the most common ischemic injury to the gastrointestinal tract. Studies from Asia have shown a seasonal variation of CI with an increased incidence in the summer months. Our study hypothesizes that in a United States population focusing within a northeastern group of hospitals, where there is a significant variation in the seasonal climate, there is a seasonal variation in the incidence and outcome for CI. Methods: We conducted a multicenter retrospective cohort study of pts admitted with biopsy-proven CI admitted to Yale-New Haven Hospital, Montefiore Medical Center, Weiler Medical Center, and SUNY-Upstate Medical Center from 2005 through 2017. For each patient, demographics, medical co-morbidities, treatments, and outcomes were recorded. Using a meteorological definition of seasons, we subdivided the population into the onset of CI during the spring (SP-CI; March to May), summer (SU-CI; June to Aug), fall (FA-CI; Sept to Nov), and winter (WI-CI; Dec to Feb). We then compared the seasonal cohorts. Our primary outcome was incidence of CI based upon the season. The secondary outcomes included combination of 30-day colectomy and mortality (i.e., poor outcome), segmental involvement, intensive care unit (ICU) requirements, length of the hospital stay (LOS), 30-day readmission and recurrence. Results: A total of 685 pts met inclusion criteria. There were no differences in incidence based upon season: CI-SP (27%), CI-SU ( 24.5%), CI-FA ( 22%) and CI-WI ( 26.4%). There were also no differences with regards to age, gender or BMI. No differences were observed in the presentation, medical comorbidities, Charlson Comorbidity Index or treatment patterns among the four groups. When considering outcomes, 30-day colectomy was observed 10.3%, 8.2%, 9.2% and 11.1% in the CI-SP, CI-SU, CI-FA and CI-WI group, respectively (p=0.84). There were also no significant differences when considering 30-day mortality or poor-outcome. LOS, ICU requirements, segmental involvement, 30-day readmission and 30- day recurrence were not significantly different between the four groups (Table). Conclusion: Our study showed no difference in the distribution of biopsy-proven cases of CI based upon seasonal change. This is in contrast to Asian based studies. It is possible that the severity of the cases considered in our study are different than the Asian studies and that mild cases might have a seasonal variation that are less likely to undergo a colonoscopy to confirm the diagnosis. Table 1. - Baseline characteristics and outcomes Outcomes Spring Summer Fall Winter p value (SP-CI) (SU-CI) (FA-CI) (WI-CI) 27.0% (185) 24.5% (168) 22.0% (151) 26.4% (181) Demographics Age (years), median (IQR) 70 (63 - 80) 69 (61 - 79) 72 (64 - 80) 70 (60 - 80) 0.988 Female 135 (72.9%) 125 (74.4%) 114 (75.5%) 133 (73.4) 0.957 BMI, median (IQR) 27.68 (23.83-32.14) 26.78 (22.86-30.67) 28.22 (24.80-31.7) 27.06 (23.39-32.11) 0.935 Presentation Tachycardia 17.8% (33) 17.8% (30) 20.5% (31) 20.4% (37) 0.857 Hypotension 6.4% (12) 8.3% (14) 5.3% (8) 9.4% (17) 0.485 Peritoneal signs 7.6% (14) 6.6% (11) 7.2% (11) 11.6% (21) 0.316 Medical comorbidities Chronic pulmonary disease 19.4% (36) 24.4% (41) 22.5% (34) 21.5% (39) 0.727 Colon cancer 2.1% (4) 1.1% (2) 1.3% (2) 2.2% (4) 0.837 Coronary artery disease 30.8% (57) 26.3% (44) 32% (48) 27.2% (49) 0.616 Diabetes mellitus 30.2% (56) 32.7% (55) 34.4% (52) 29.2% (53) 0.738 Hypertension 73.5% (136) 78.5% (132) 81.4% (123) 76.8% (139) 0.364 Hemodialysis 10.1% (9) 10.3% (10) 5.8% (5) 12.6% (11) 0.510 Hypercoagulable state 0.5% (1) 0.6% (1) 0.7% (1) 1.1% (2) 0.915 Malignancy (any) 14% (26) 18.4% (31) 14% (21) 17.7% (32) 0.557 Malignancy with metastasis 3.8% (1) 6.4% (2) 9.5% (2) 9.3% (3) 0.837 Peripheral vascular disease 10.3% (19) 5.3% (9) 6.6% (10) 7.2% (13) 0.324 Stroke 8.1% (15) 8.3% (14) 11.9% (18) 13.8% (25) 0.226 Calculated Charlson Score, mean (SD) 5 (2.7) 5 (2.8) 5.2 (2.8) 5.1 (3.0) 0.979 Bowel Segment Involvement Small bowel involvement 6.8% (8) 7.2% (7) 4% (4) 7.3% (8) 0.732 Pancolitis 5.6% (10) 2.5% (4) 4.8% (7) 8.3% (15) 0.122 Any right colon involvement 24.8% (40) 27.3% (41) 21.8% (29) 28.6% (45) 0.564 Right colon only 13.5% (23) 16.6% (26) 10.6% (15) 14.7% (25) 0.500 CI Severity Mild CI 0.5% (1) 0% (0) 0% (0) 1.12% (2) 0.390 Moderate CI 46.9% (86) 49.1% (82) 56.3% (84) 49.1% (88) Severe CI 52.4% (96) 50.9% (85) 43.6% (65) 49.7% (89) Presence of necrosis on colonoscopy 9.8% (16) 10.4% (16) 8.2% (11) 5.4% (9) 0.372 ICU requirement 22.5% (41) 24.2% (39) 18.2% (27) 25.9% (46) 0.400 Outcomes 30-day colectomy 10.3% (19) 8.3% (14) 9.2% (14) 11.1% (20) 0.842 30- day mortality 5.4% (10) 3.5% (6) 4% (6) 6.6% (12) 0.546 Combined poor outcome (30- day colectomy and/or 30-day mortality) 13.5% (25) 9.5% (16) 11.3% (17) 15% (27) 0.437 Length of stay (mean, (SD)) 6.2 (16.9) 10.3 (56.6) 8.4 (31.2) 10.1(55.2) 0.137 C Difficile as a complication 3.4% (6) 2.5% (4) 2.8% (4) 3.1% (5) 0.97 30-day Readmission 13.5% (25) 10.7% (18) 7.3% (11) 9.9% (18) 0.328 30-day Recurrence 3.7% (7) 1.7% (3) 0% (0) 2.2% (4) 0.112 Abbreviations: BMI, Body mass index; CI, colon Ischemia; ICU, Intensive Care Unit.