Impact of Oral Mesalamine on Clinical Remission and Mucosal Response in Mild to Moderate Ulcerative Colitis: A Prospective Observational Study

Background Ulcerative colitis (UC) is one of the two main types of inflammatory bowel disease (IBD)--the other being Crohn's disease--in which achieving both clinical remission and mucosal healing is essential for optimal long-term outcomes. Objective The objective of this study is to evaluate the impact of oral mesalamine on achieving clinical remission and mucosal healing in patients with mild to moderate UC in a real-world clinical setting. Methodology This prospective observational study was conducted from April 2023 to March 2024 at two tertiary care hospitals in Pakistan: Abbas Institute of Medical Sciences, Muzaffarabad, and HBS Medical and Dental College, Islamabad. A total of 404 adult patients (222 males, 54.95%; 182 females, 45.05%) diagnosed with mild to moderate UC were enrolled. For mild conditions, the doctor recommended 2.4 g of oral mesalamine per day, and for moderate disease, 4.8 g per day. Patients were assessed at 8, 12, and 24 weeks to determine clinical remission, defined as the absence of rectal bleeding and normalization of stool frequency, and mucosal healing, defined as a Mayo endoscopic subscore of 0 or 1. Data were analyzed using SPSS version 25 (IBM Corp., Armonk, NY, US). Chi-square tests and independent t-tests were applied, with a p-value of <0.05 considered statistically significant. Results Of the 404 patients, 367 (90.84%) completed the 24-week follow-up. Clinical remission was achieved in 238 (60.71%) at 8 weeks, 288 (76.39%) at 12 weeks, and 328 (89.37%) at 24 weeks. Mucosal healing was observed in 211 (54.10%) at 8 weeks, 265 (70.29%) at 12 weeks, and 282 (78.12%) at 24 weeks. Among those receiving 2.4 g/day (n=194), 172 (88.66%) achieved remission; in the 4.8 g/day group (n=173), 156 (90.17%) achieved remission. Conclusion Oral mesalamine is highly effective in inducing clinical and mucosal response in mild to moderate UC in routine practice.