Outcome of Ulcerative Colitis 20 Years after Diagnosis in a Prospective Population-based Inception Cohort from South-Eastern Norway, the IBSEN Study

Abstract

Background and aims: The long-term course of ulcerative colitis [UC] is difficult to predict. Mortality, colectomy, cancer, and hospitalisation represent hard outcomes of disease. Moreover, knowledge on the risk of relapses and need for potent medication add important information about living with UC. We aimed to evaluate the course and prognosis of UC during the first 20 years after diagnosis, and to identify early prognostic risk factors.

Methods: From 1990 to 1994, a population-based inception cohort of patients with inflammatory bowel disease was enrolled in South-Eastern Norway. A systematic follow-up [FU] was conducted at 1,5, 10, and 20 years after diagnosis. Clinical outcomes were recorded continuously, and possible relationships between early disease characteristics and outcomes were analysed using multiple regression analysis.

Results: Among 519 UC patients, 119 died, 60 were lost to FU, and 340 were included in the FU cohort. The 20-year cumulative risk of colectomy was 13.0% (95% confidence interval [CI] [11.4-14.6]). Extensive colitis at diagnosis was independently associated with an increased risk of colectomy compared with proctitis (hazard ratio [HR] = 2].8, 95% CI [1.3-6.1]). In contrast, mucosal healing at 1-year FU was independently associated with reduced risk of colectomy [HR = 0.4, 95% CI [0.2-0.8]), and inversely associated with subsequent risk of relapse [adjusted HR = 0.5, 95% CI [0.3-0.7]).

Conclusions: The overall risk of colectomy in our cohort was lower than expected from previous studies, although considerable for patients with extensive colitis at diagnosis. Early mucosal healing was associated with better disease outcomes 20 years after diagnosis.

Keywords: Ulcerative colitis; clinical outcome; population-based inception cohort.

Figure 1.

Flowchart of the IBSEN cohort from inception to the end of the 20-year follow-up [FU] period.

Figure 2.

Four predefined curves depicting different courses of ulcerative colitis [UC] from diagnosis to the end of the 20-year follow-up [FU] period. Patients’ self-assessment of disease course.

Figure 3.

a. Mortality [%] in UC according to disease extent during the 20-year FU period. b. Observed survival rate for the UC cohort [n = 519] during 20 years of follow-up compared with expected survival rate derived from life tables, and their ratio: the relative survival rate. UC, ulcerative colitis; FU, follow-up.

Figure 4.

Proportion of UC [ulcerative colitis] patients [%] in the total cohort [n = 519] in relapse or remission per year from diagnosis onwards. The patients were followed up until the date of their last visit in the study, their death, or colectomy. The number of patients is shown in parentheses. The median follow-up period was 18.6 years [range: 0–22 years].

Figure 5.

a. Cumulative rate [%] of colectomy during the 20-year FU period according to the extent of UC at diagnosis. b. Cumulative rate [%] of colectomy during the first 20 years after the diagnosis of UC in patients with mucosal healing vs. mucosal inflammation at 1-year FU. UC, ulcerative colitis; FU, follow-up.

Figure 6.

Cumulative drug consumption after initial treatment for ulcerative colitis [UC] during the first 10 years [black bars] versus the last 10 years [patterned bars]. ±Data missing in 17 cases.

Figure 7.

Proportions of UC patients [%] using systemic steroids in the 20-year FU cohort according to disease extent at diagnosis. E1: proctitis, E2: left-sided colitis, E3: extensive colitis. UC, ulcerative colitis; FU, follow-up.