S269 Smoking out the Relationship Between Ulcerative Colitis and Cigarette Use: Insights from a Propensity Matched Study

Introduction: Ulcerative colitis (UC) is a chronic inflammatory disorder affecting the colon. Previous studies have indicated that smoking can reduce disease activity in UC, and symptoms may worsen upon smoking cessation. In this study, we aimed to analyze smoking trends in UC and investigate the association between smoking and UC-related complications. Methods: We utilized the National Inpatient Sample (NIS) database to create a 1:1 matched cohort of UC patients without a history of smoking. The matching was based on biodemographic and hospital characteristics, as well as 31 Elixhauser comorbidities. We compared UC-related outcomes between the matched cohorts using the Chi-square test for categorical variables and the student's t-test for continuous variables. Univariate and multivariate linear and logistic regression models were constructed, incorporating known confounders, and variables with a P-value of < 0.2 on univariate analysis. A statistically significant threshold was set at P≤0.05. Results: A total of 550,075 patients with UC were identified, of which 59,145 (10.75%) were smokers. After 1:1 matching, we paired 47,975 smoker patients with an equal number of non-smoker patients. Smokers were 13% more likely to have uncomplicated UC. Smoking in UC was associated with a 21% lower mortality rate, a 0.46-day decrease in length of stay (LOS), and a $5,549 reduction in mean inpatient cost (MIC) compared to non-smokers. Smoking was also linked to a 16% lower odds of gastrointestinal (GI) bleeding but a 22% higher odds of intestinal perforation in comparison to non-smokers. Notably, in recent years, there is an increase in all-cause mortality and intestinal perforation related to UC, paralleling the trends in smoking. Conclusion: This study bolsters the idea of a protective effect of smoking on UC, likely because byproducts such as nicotine and carbon monoxide have an immunomodulatory effect on autoantibody production, cytokine formation and leukocyte migration, leading to overall suppressed immunological response. This effect may also be site and tissue specific as some studies show that cigarette smoke may intensify damage in the small intestine but reduce colitis, possibly because caustic components are metabolized earlier in GI tract and specific microbiota and specialized epithelial cells in the colon have differential immune response compared to other parts of GI tract. This may also account for differences in the effect of smoking on UC versus other GI inflammatory diseases like Crohn’s.Figure 1.: National Ulcerative Colitis related Trends in the United States 2016-2020. Table 1. - Ulcerative Colitis Related Hospitalizations in the US 2016-2020 Stratified by Smoking Status Matched cohorts of UC Non-smoker Active smoker P-value Number of hospitalizations (n) 47,975 47,975 Mean age in years (SE) 52.17 (19.07) 52.22 (15.96) 0.670 Gender Male 22,738 (47.40%) 22,705 (47.33%) 0.830 Female 25,237 (52.60%) 25,270 (52.67%) Race White 37,350 (77.85%) 37,495 (78.16%) 0.640 Black 5,525 (11.52%) 5,490 (11.44%) Hispanic 3,285 ( 6.85%) 3,245 ( 6.76%) Asian or Pacific Islander 435 ( 0.91%) 400 ( 0.83%) Others 1,380 ( 2.88%) 1,345 ( 2.80%) Median household income national quartile for patient ZIP Code $1-$43,999 14,656 (30.55%) 14,590 (30.41%) 0.130 $44,000-$55,999 13,284 (27.69%) 13,410 (27.95%) $56,000-$73,999 11,733 (24.46%) 11,480 (23.93%) $74,000 or more 8,302 (17.30%) 8,495 (17.71%) Insurance type Medicare 18,176 (37.89%) 18,370 (38.29%) 0.150 Medicaid 11,519 (24.01%) 11,225 (23.40%) Private including HMO 15,130 (31.54%) 15,240 (31.77%) Others 3,150 ( 6.57%) 3,140 ( 6.55%) Elixhauser Comorbidity Index (ECI) 0 3,388 ( 7.06%) 3,610 ( 7.52%) 0.003 1 7,096 (14.79%) 7,045 (14.68%) 2 9,424 (19.64%) 9,090 (18.95%) ≥ 3 28,067 (58.50%) 28,230 (58.84%) Bed size of hospital Small 10,275 (21.42%) 10,140 (21.14%) 0.370 Medium 14,193 (29.58%) 14,120 (29.43%) Large 23,507 (49.00%) 23,715 (49.43%) Hospital teaching status Non-Teaching Hospital 14,495 (30.21%) 14,250 (29.70%) 0.084 Teaching Hospital 33,480 (69.79%) 33,725 (70.30%) Region of hospital Northeast 10,088 (21.03%) 10,085 (21.02%) 0.660 Midwest 11,808 (24.61%) 11,665 (24.31%) South 17,542 (36.56%) 17,700 (36.89%) West 8,537 (17.79%) 8,525 (17.77%) Inpatient outcomes Unadjusted Outcomes Adjusted Outcomes Non-smoker Active smoker P-value AOR(95% CI),P-value Inpatient mortality (%) 870 ( 1.81%) 670 ( 1.40%) < 0.001 0.79(0.71-0.88), P=0.000 LOS (days) 5.58 (0.03) 5.11 (0.03) < 0.001 -0.46(-0.54- -0.39), P=0.000 MIC (USD) 60691(432) 55069(366) < 0.001 -5549(-6632- -4466), P=0.000 Uncomplicated UC 42,904 (89.43%) 43,505 (90.68%) < 0.001 1.13(1.09-1.18), P=0.000 GI bleeding 4,058 ( 8.46%) 3,410 ( 7.11%) < 0.001 0.84(0.80-0.89), P=0.000 Intestinal perforation 201 ( 0.42%) 245 ( 0.51%) 0.037 1.22(1.01-1.47), P=0.036 Intestinal obstruction 246 ( 0.51%) 265 ( 0.55%) 0.400 1.07(0.90-1.28), P=0.429 Toxic megacolon 10 ( 0.02%) 10 ( 0.02%) 1.000 1.02(0.42-2.46), P=0.961 UC; ulcerative colitis, SE; standard error, AOR; adjusted odds ration, CI; confidence interval, LOS; length of stay, MIC; mean inpatient cost, GI; gastrointestinal.