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* = Presenting author

P429. Natural history of ulcerative colitis by the age group at diagnosis: a 10-year nationwide retrospective cohort from the Veterans Affairs healthcare system

A. Abbas1, Y. Koleva2, N. Khan2, 1Tulane University, Gastroenterology, New Orleans, United States, 2Southeast Louisiana Veterans Health Care System, Gastroenterology, New Orleans, United States

Background

There is limited data regarding the interaction between age of onset of ulcerative colitis (UC) and the natural history of the disease. Our aim was to assess the potential effect of age at diagnosis on the long term probabilities of steroid and thiopurines utilization as well as the need for colectomy using a nationwide cohort.

Methods

UC patients followed by the Veterans Affairs healthcare system between 2001 and 2011 were identified. We included all the patients who had ICD9 code of UC and pharmacy fillings of 5-ASA compounds to increase the specificity of UC patients' identification. The index date UC code assignment for the patient was considered as the date of diagnosis. Age at diagnosis was identified and the cohort was classified according to that into: young (18–39), middle (40–64) and old (≥65) age. Patients were followed-up from that date by tracking their pharmacy and procedures records. Cumulative probabilities of receiving steroids, thiopurines and colectomy were calculated using Kaplan–Meier survival curves and compared using Log Rank test.

Results

We included 22,760 patients with a median follow-up of 5 years to our analysis. Majority were white males (Caucasians 76%, male 93%). Fourteen percent of the patients were classified as young, 51% middle and 36% old age at diagnosis. Cumulative probabilities of steroids use at 1, 5 and 10 years was 30%, 62% and 91% for young compared to 10%, 20% and 28% for old respectively, p < 0.001, Figure 1.

Cumulative probabilities of thiopurines use at 1, 5 and 10 years was 18%, 35% and 44% for young compared to 5%, 10% and 14% for old respectively, p < 0.001.Cumulative probabilities of colectomy at 1, 5 and 10 was 2%, 6% and 9% for young compared to 1%, 2% and 4% for old respectively, p < 0.001.

Figure 1. Cumulative probability of using steroids by age group at UC diagnosis. Kaplan–Meier analysis, p < 0.001.

Conclusion

In this large nationwide cohort of UC patients, older age at diagnosis was associated with significant reduction in the cumulative probabilities of receiving steroids, thiopurines and colectomy. This might suggest that a milder disease activity for those diagnosed at elderly compared to those diagnosed while in younger age groups.