Assessment of 5-Aminosalicylic Acid Prescription Patterns and Treatment Outcomes in Patients With Ulcerative Colitis in Korea

Inclusion Criteria: * Patients who were diagnosed with UC during the index period. * Patients who had at least two claims of 5-ASA (sulfasalazine, balsalazide, mesalamine) during the index period. * Patients who underwent at least one endoscopy within a 3-month period prior to the index date (i.e. the first date of diagnosis with UC). * Defined as a claim with relevant endoscopy procedure code. * Include the upper gastrointestinal endoscopy, colonoscopy, sigmoidoscopy, which are identified using the procedure code. * Patients who were treated with 5-ASA continuously for at least 1-month after the index date. * Defined as those who were treated with 5-ASA for more than 30 days within 6-month after the index date (i.e. the first date of diagnosis with UC). Exclusion Criteria: * Patients less than 15 years old as of the index date (\<15 years old). * Patients who were treated with 5-ASA during the baseline period (i.e. 12-month prior to the index date). * Patients who were diagnosed with UC during the baseline period. * Patients who received steroids, immunosuppressants, or biologics during the baseline period. * Steroid includes both oral medication and intravenous (IV) injection. The analysis will include the moderate- to high-dose of cumulative steroid use, which is defined as \>=30mg of prednisolone, \>= 50mg of methylprednisolone, or \>=50mg of hydrocortisone. * Immunosuppressants is defined as at least one claim with Azathioprine or 6-Mercaptopurine. * Biologics is defined as at least one claim with Infliximab, Adalimumab, Ustekinumab, Vedolizumab, Golimumab, or Tofacitinib. * Patients who were diagnosed with Crohn's disease at any time in the overall study period. * Defined as a claim with relevant Crohn's disease code recorded as primary diagnosis during the baseline period or follow-up period (i.e. entire study period).