INTRODUCTION: Clostridium difficile infection (CDI) is the most common nosocomial infection in the US. Studies have shown that elderly patients are at increased risk of CDI. We performed an analysis of Nationwide Inpatient Sample (NIS) to assess the outcomes of CDI colitis in hospitalized patients according to age. METHODS: We queried the 2016 and 2017 NIS databases using the ICD-10 codes to identify patients admitted with a primary diagnosis of CDI. Patients were stratified into age categories (18–40 Years, 41–60 years, 61–80 years and >80 years), 18–40 years was taken as reference for analysis. Outcomes measured were all-cause in-hospital mortality, Length of Stay (LOS), Hospitalization charge, shock, ICU admission, Acute Kidney Injury (AKI) and home discharge. A multivariate logistic regression analysis was performed to obtain Odds Ratio (OR) of the association. Statistical analysis was performed using STATA software. RESULTS: A total of 188,070 adult patients with CDI were included in the study. Mean age was 65.9 years, and majority of patients were female (64.66%). When stratified by age, 10.71% patients were aged 18-40 years, 23.45% aged 41–60 years, 41.01% aged 61–80 years and 24.83% more than 80 years. On multivariate analysis, advancing age groups had significantly higher in-hospital mortality [(0.1% vs 0.5% vs 1.28% vs 2.62%; P < 0.01), (aOR 4.98 vs 9.94 vs 23.07; P < 0.01)], mean LOS (4.45 days vs 5.11 days vs 5.65 days vs 5.88 days; P < 0.01), mean hospitalization charges ($35,887 vs $40,787 vs $42,890 vs $40,906; P < 0.01), shock [(0.4% vs 1.08% vs 1.5% vs 1.2%; P < 0.01), (aOR 2.6 vs 3.7 vs 3.2; P < 0.01)], AKI [(7.2% vs 16.7% vs 26.8% vs 31.5%; P < 0.01), (aOR 2.1 vs 3.5 vs 4.7; P < 0.01)], and lower likelihood of home discharge [(89.5% vs 79.2% vs 55.3% vs 29.1%; P < 0.01), (aOR 0.57 vs 0.26 vs 0.08; P < 0.01)]. CONCLUSION: In our study, we found that CDI is more common in elderly population. With advancing age, patients had higher in-hospital all-cause mortality, longer LOS, higher mean hospitalization costs. They were also more likely to have shock and AKI, and less likely to be discharged home. Some of the reasons for this may be higher comorbidities in the elderly population leading to increased hospital admissions and antibiotics use, and age associated physiological changes. Further studies are needed to explore the precise mechanisms and improve outcomes in elderly patients.Figure 1.: Outcomes in patients with Clostridium difficile colitis stratified by age group.