Segmental Histological Normalisation Occurs in Ulcerative Colitis but Does Not Improve Clinical Outcomes

The evolving understanding of histology as an endpoint in ulcerative colitis

A therapeutic goal for patients with ulcerative colitis (UC) is deep remission including clinical remission and mucosal healing. Mucosal healing was previously defined by endoscopic appearance, but recent studies demonstrate that histological improvements can minimize the risks of experiencing clinical relapse after achieving endoscopic remission, and there is growing interest in the value and feasibility of histological targets of treatment in inflammatory bowel disease, and specifically UC. In this review article, we identify remaining challenges and discuss an evolving role of histology in the management of UC.

Deep mucosal healing in ulcerative colitis: how deep is better?

Ulcerative colitis (UC), characterized by its recurrent nature, imposes a significant disease burden and compromises the quality of life. Emerging evidence suggests that achieving clinical remission is not sufficient for long-term remission. In pursuit of a favorable prognosis, mucosal healing (MH) has been defined as the target of therapies in UC. This paradigm shift has given rise to the formulation of diverse endoscopic and histological scoring systems, providing distinct definitions for MH. Endoscopic remission (ER) has been widely employed in clinical practice, but it is susceptible to subjective factors related to endoscopists. And there's growing evidence that histological remission (HR) might be associated with a lower risk of disease flares, but the incorporation of HR as a routine therapeutic endpoint remains a debate. The integration of advanced technology has further enriched the definition of deep MH. Up to now, a universal standardized definition for deep MH in clinical practice is currently lacking. This review will focus on the definition of deep MH, from different dimensions, and analyze strengths and limitations, respectively. Subsequent multiple large-scale trials are needed to validate the concept of deep MH, offering valuable insights into potential benefits for UC patients.

Histological Disease Activity as Predictor of Clinical Relapse, Hospitalization, and Surgery in Inflammatory Bowel Disease: Systematic Review and Meta-Analysis

BACKGROUND

The clinical impact of histological remission on short- and long-term clinical outcomes in patients with inflammatory bowel disease (IBD) is not well established. We assessed risk of clinical relapse, hospitalization, and need for surgery in patients achieving histological remission in comparison with active histological disease.

METHODS

A systematic review was conducted using MEDLINE, Scopus, Cochrane CENTRAL, EMBASE, and conference abstracts from inception to November 2022. Our main outcome was the rate of clinical relapse in patients with IBD who reached histological remission vs patients with active histological disease. Secondary outcomes were clinical complications of IBD such as hospitalization and need for surgery. The endpoints were investigated at 2 time points, 6 to 12 months (short term) and >12 months (long term).

RESULTS

Short-term outcome analysis showed that the risk of clinical relapse was significantly higher in ulcerative colitis patients with active histological disease in comparison with patients at histological remission (risk ratio [RR], 2.41; 95% confidence interval [CI], 1.69-3.44; P < .01). The risk of hospitalization in ulcerative colitis patients was not significant among the 2 groups (RR, 4.22; 95% CI, 0.91-19.62; P = .07). Long-term outcome analysis demonstrated that the risk of clinical relapse (RR, 2.07; 95% CI, 1.55-2.76; P < .01), need for surgery (RR, 3.14; 95% CI, 1.53-6.45; P < .01), and hospitalization (RR, 2.52; 95% CI, 1.59-4.00; P < .01) was significantly higher in patients with active histological disease.

CONCLUSIONS

Histological remission in IBD represents an important therapeutic goal that is not yet routinely pursued in clinical practice. In our study, patients who achieved histological remission have more favorable outcomes than those with active histological disease in ulcerative colitis.

Histological healing as a predictor of sustained clinical remission in paediatric ulcerative colitis

BACKGROUND

The study aimed to assess the longitudinal impact of endoscopic healing (EH) and histological healing (HH) in a cohort of paediatric patients affected by ulcerative colitis (UC).

METHODS

This was a retrospective single-centre longitudinal study. 86 children with UC who underwent endoscopic re-assessment while in clinical and biochemical remission were included. Partial EH was defined as a Mayo Endoscopic Subscore (MES) of 1 and complete EH was defined as a MES of 0. HH was defined as the absence of active inflammation in all biopsies. The cumulative incidence of clinical relapse was evaluated during follow-up.

RESULTS

At the second endoscopic re-evaluation, 59 (68.6%) patients achieved EH (MES ≤1). Of these patients, 39 (66%) achieved complete EH. 20 of the 39 patients who achieved complete EH attained complete HH. Patients who achieved partial and complete EH showed higher recurrence-free survival rates compared to those who did not (p < 0.01 and p < 0.01, respectively). Amongst patients with complete EH, those who achieved complete HH had lower recurrence rates when compared to patients who still showed microscopic inflammation (p = 0.049).

CONCLUSION

Achievement of EH and HH is associated with fewer disease relapses, with patients achieving HH showing longer relapse-free survival rates.

Intestinal Ultrasound Is Accurate to Determine Endoscopic Response and Remission in Patients With Moderate to Severe Ulcerative Colitis: A Longitudinal Prospective Cohort Study

BACKGROUND & AIMS

Intestinal ultrasound (IUS) is noninvasive, cost-effective, and accurate to determine disease activity in ulcerative colitis (UC). In this study, we prospectively evaluated IUS for treatment response in a longitudinal cohort by using endoscopy and histology as gold standards.

METHODS

Consecutive patients with moderate to severe UC (endoscopic Mayo score [EMS] ≥2) starting tofacitinib treatment were included. Patients were evaluated at baseline and after 8 weeks of tofacitinib induction by means of clinical, biochemical, endoscopic (EMS and UC endoscopic index for severity), histologic (Robarts Histopathologic Index) and IUS assessments. Readers of IUS, endoscopy, and histology were blinded for all other outcomes. The primary outcome was difference in bowel wall thickness (BWT) for endoscopic improvement vs no endoscopic improvement. Endoscopic remission was defined as EMS = 0, improvement as EMS ≤1, and response as a decrease of EMS ≥1.

RESULTS

Thirty patients were included, with 27 patients completing follow-up. BWT correlated with EMS (ρ = 0.68, P < .0001), UC endoscopic index for severity (ρ = 0.73, P < .0001) and Robarts Histopathologic Index (ρ = 0.49, P = .002) at both time points. BWT in the sigmoid was lower in patients with endoscopic remission (1.4 mm vs 4.0 mm, P = .016), endoscopic improvement (1.8 mm vs 4.5 mm, P < .0001) and decrease in BWT was more pronounced in patients with endoscopic response (-58.1% vs -13.4%, P = .018). The most accurate cutoff values for BWT were 2.8 mm (area under the curve [AUC] 0.87) for endoscopic remission, 3.9 mm (AUC 0.92) for improvement, and decrease of 32% (AUC 0.87) for response. The submucosa was the most responsive wall layer.

CONCLUSION

IUS, importantly BWT as the single most important parameter, is highly accurate to detect treatment response when evaluated against endoscopic outcomes.

Characteristics and Outcomes of Left-sided Ulcerative Colitis With a Cecal/Periappendiceal Patch of Inflammation

Ulcerative colitis (UC) is characterized by continuous mucosal inflammation of the rectum, extending uninterrupted to a variable portion of the colon proximally. However, in some patients with distal colitis, a distinct pattern of skip inflammation (so-called patch) involves the cecum and/or appendiceal orifice, but data on this entity are contradictory, and its significance and prognosis are still debated. We identified 102 adult cases of left-sided UC with a cecal/periappendiceal patch and compared them to 102 controls (left-sided UC only) along clinicopathologic characteristics and disease outcomes. In multivariate analysis, patients with a patch were younger (median age: 31 vs. 41 y; P =0.004) and more likely to have rectosigmoid involvement only (58.8% vs. 28.4%; P <0.001), compared with patients without a patch. During follow-up, patients with a patch were more likely to be eventually diagnosed with Crohn disease (CD) (9.8% vs. 1.0%; P =0.022) and to show proximal extension of inflammation (35.6% vs. 10.0%; P =0.021), but showed no differences in rates of neoplasia, colectomy, or pharmacotherapy escalation. Kaplan-Meier analysis confirmed that patients with a biopsy diagnosis of cecal/periappendiceal patch were more likely to show proximal disease extension ( P <0.001) and to be diagnosed with CD ( P =0.008). In conclusion, cecal/periappendiceal skip inflammation in left-sided UC occurs more often in younger patients and in those with rectosigmoid involvement and is associated with proximal disease extension and, in a small fraction of cases, change of diagnosis to CD. However, it does not portend increased risk of neoplasia, pharmacotherapy escalation, or subsequent colectomy, compared with patients with left-sided UC only.

Spatial Evolution of Histologic and Endoscopic Healing in the Left and Right Colon in Patients With Ulcerative Colitis

BACKGROUND AND AIMS

Despite increasing interest in histologic remission as a treatment target in ulcerative colitis (UC), the accuracy of histologic findings in left colon in detecting pancolonic histologic remission is unknown.

METHODS

In a retrospective cohort study of patients with endoscopically active pancolitis undergoing treat-to-target interventions, we evaluated the diagnostic accuracy of left-sided (distal to splenic flexure) histologic and endoscopic findings on colonoscopy for detecting histologic and endoscopic healing elsewhere in the colon.

RESULTS

Of 86 patients with moderate to severely active pancolitis who underwent 2 consecutive colonoscopies during treat-to-target interventions, 38% and 51% achieved histologic and endoscopic remission, respectively. Substantial agreement (kappa, 0.67; 95% confidence interval (CI), 0.51-0.83) was observed in histologic findings between left and right colon on follow-up colonoscopy. Histologic, and endoscopic, findings in left colon showed excellent accuracy in detecting pancolonic histologic remission (area under the curve (AUC), 0.96 [95% CI, 0.93-1.0]; misclassification rate, 5.9%), histologic normalization (AUC, 1.0, 0%), endoscopic improvement (AUC, 0.95 [0.96-1.0], 3.5%) and endoscopic remission (AUC, 0.98 [0.96-1.00], 5.8%), respectively.

CONCLUSIONS

In patients with active pancolitis undergoing treat-to-target interventions, histologic and endoscopic findings in the left colon on colonoscopy have excellent accuracy for detecting pancolonic histologic remission, histologic normalization, endoscopic improvement, and endoscopic remission. Flexible sigmoidoscopy may suffice for monitoring histologic and endoscopic activity in patients with pancolitis.

Endoscopic remission assessed with PICaSSO virtual electronic chromendoscopy accurately predicts clinical outcomes in ulcerative colitis

BACKGROUND AND AIMS

A composite endoscopic-histologic remission is increasingly explored as an important endpoint in ulcerative colitis (UC). We investigated combined endoscopic-histologic remission for predicting clinical outcomes at 12 months compared with endoscopic remission alone using the high definition virtual chromoendoscopy (VCE) Paddington International virtual ChromoendoScopy ScOre (PICaSSO) and histology scores.

METHODS

Ulcerative colitis patients, prospectively enrolled from 11 international centres, underwent VCE with targeted biopsies and followed up for 12 months. Endoscopic activity was assessed by Mayo Endoscopic Score (MES), Ulcerative Colitis Endoscopic Index Severity (UCEIS) followed by VCE-PICaSSO. Robarts Histopathological Index|Robarts Histological index≤3 without neutrophils in mucosa, and Nancy Histological index (NHI)≤ 1 were used to define histologic remission. Combined endoscopic-histologic remission was compared with endoscopic remission alone by Cox proportional hazards model and by two- and three-proportion analysis using pre-specified clinical outcomes.

RESULTS

307 patients were recruited and 302 analysed. There was no difference in survival without specified clinical outcomes between PICaSSO defined endoscopic remission alone and endoscopic plus histologic remission in the rectum (HR 0.42, 95%CI 0.16-1.11 and HR 1.03, 95%CI 0.42-2.52 for Robarts Histological index and NHI respectively) at 12 months. There was however a significant survival advantage without specified clinical outcome events for UCEIS combined with histology compared with UCEIS alone (HR 0.30, 95%CI 0.12-0.75, p = 0.02) at 12 months (but not combined with NHI). For MES there was no advantage for predicting specified clinical outcomes at 12 months for endoscopy alone versus endoscopy plus histology, but there were differences in two and three proportion analysis at 6 months.

CONCLUSION

Endoscopic remission by VCE-PICaSSO alone was similar to combined endoscopic and histologic remission for predicting specified clinical outcomes at 12 months. Larger studies with specific therapeutic interventions are required to further confirm the findings.

Treatment Targets in Ulcerative Colitis: Is It Time for All In, including Histology?

The main therapeutic goal of ulcerative colitis (UC) is to induce and maintain remission to prevent long-term disease progression. Treat-to-target strategies, first introduced by the STRIDE consensus and updated in 2021, have shifted focus from symptomatic control toward more stringent objective endpoints. Today, patient monitoring should be based on a combination of biomarkers and clinical scores, while patient-reported outcomes could be used as short-term targets in monitoring disease activity and therapeutic response. In addition, endoscopic healing was the preferred long-term goal in UC. A Mayo endoscopic score (MES) ≤ 1 can be recommended as a minimum target. However, recent evidence suggests that more stringent endoscopic goals (MES of 0) are associated with superior outcomes. Recently, emerging data support that histological remission (HR) is a superior prognostic factor to endoscopic healing in predicting long-term remission. Despite not yet being recommended as a target, HR may become an important potential therapeutic goal in UC. However, it remains questionable if histological healing should be used as a routine assessment in addition to clinical, biomarker, and endoscopic targets in all patients. Therefore, in this review, our aim was to discuss the current evidence for the different treatment targets and their value in everyday clinical practice.

Treat-to-target approach in the management of inflammatory Bowel disease

With the advent of biologic and small molecule therapies, there has been a substantial change in the treatment of inflammatory bowel disease. These advances have had a great impact in preventing disease progression, intestinal damage and, therefore, have contributed to a better quality of life. Discordance between symptom control and mucosal healing has been demonstrated. This has led to the search for new disease control targets. The treat to target strategy, based on expert recommendations and now a randomized controlled trial, has determined that clinical and endoscopic remission should be the goal of therapy. Biomarkers (fecal calprotectin) can be a surrogate target. Although histological healing has shown benefits, there is inadequate evidence and inadequate therapy for that to be a fixed goal at this time. This review will focus on therapeutic goals, according to the evidence currently available, and evaluate strategies to achieve them.