Effectiveness of Sulfasalazine Therapy Following Mesalazine Treatment Failure in Children with Ulcerative Colitis.

Purpose: This study aimed to assess the effectiveness of sulfasalazine therapy in children with ulcerative colitis (UC) after mesalazine treatment failure and to compare its effectiveness with that of mesalazine and azathioprine used after the first relapse. Methods: Data from all children newly diagnosed with UC between January 2010 and December 2021 who had at least 12 months of follow-up were retrospectively analyzed. Results: Of 189 children newly diagnosed with UC, 99 (52.4%) were treated with mesalazine alone, experienced a relapse, and were included in the study. The mean age was 12.8 years (standard deviation, 0.45), and 56 patients (56.6%) were male. After relapse, 35 children (35.4%) switched to sulfasalazine. Sulfasalazine treatment was effective in 28 patients (80.0%), and 19 patients (54.3%) remained relapse-free at 12 months. Patients who switched to sulfasalazine had more extensive disease and a higher Pediatric Ulcerative Colitis Activity Index than those who continued mesalamine treatment, but both disease extent and the index were lower than in patients who received azathioprine. Relapse-free survival did not differ among mesalazine, sulfasalazine, and azathioprine treatments ( Conclusion: Switching from mesalazine to sulfasalazine may be a viable therapeutic option for carefully selected children with mild to moderate UC, even after mesalazine treatment failure.