Prevalence and Outcomes of No Treatment Versus 5-ASA in Ulcerative Colitis: A Nationwide Analysis From the epi-IIRN

Background: Data regarding patients with ulcerative colitis (UC) not receiving maintenance treatment are scarce. In this nationwide study, we aimed to explore the frequency and long-term outcomes of untreated patients with UC vs treated patients. Methods: We retrieved data from Israel's Health Maintenance Organizations, covering 98% of the population. No maintenance treatment (NMT) was defined as lack of treatment during the period from 3 to 6 months from diagnosis, allowing at most 3 months for induction treatment. Results: A total of 15 111 patients have been diagnosed with UC since 2005, of whom 4410 (29%) have had NMT, with 36 794 person-years of follow-up. NMT was more likely in adults (31%) and in elderly-onset UC (29%) than in pediatric-onset UC (20%; P <. 001) and decreased from 38% in 2005 to 18% in 2019 (P <. 001). The probability of remaining without treatment was 78%, 49%, and 37% after 1, 3, and 5 years from diagnosis, respectively. In propensity score-matched analysis of 1080 pairs of treated (93% with 5-aminosalicylic acid) and untreated patients, outcomes were comparable for time to biologics (P =. 6), surgery (P =. 8), steroid dependency (P =. 09), and hospitalizations (P =. 2). Multivariable modeling indicated that failing NMT was less likely in adults or elderly-onset patients who received at most rectal therapy or antibiotics as induction therapy. Conclusions: Nowadays, 18% of patients with UC do not receive maintenance therapy, of whom half remain without treatment after 3 years. Matched pairs of patients on NMT and 5-aminosalicylic acid, representing the mildest patients of the latter, had similar outcomes. Prospective studies are needed to further explore the role of NMT in UC.