IBD Disease Activity Assessment: What Should We Do in Clinical Practice?

The goals of therapy for inflammatory bowel disease (IBD) have changed over time, said Bruce Sands, MD, in his session “Disease Activity Assessment: What Should We Do in Clinical Practice?” which opened the Advances in Inflammatory Bowel Disease (AIBD) 2020 virtual meeting on Wednesday, December 9.

Dr Sands is the Dr Burrill B. Crohn Professor of Medicine and chief of the Division of Gastroenterology at Icahn School of Medicine at Mount Sinai in New York City. 

“Years ago we were happy to have clinical response, and then even happier to achieve clinical remission,” Dr. Sands said. “Now we are turning to deeper and deeper definitions of remission all the way to ‘deep remission’,” looking for normalization of not only symptoms but also biomarkers on laboratory tests, and even further to mucosal healing and normal endoscopy. Ultimately what we really want to do is to improve patient outcomes, improve the patient’s quality of life, prevent hospitalizations, and avoid surgery and disabilities.”

Gastroenterologists must distinguish between disease activity and disease severity, Dr Sands said. Disease activity can be simply described as “How is your patient TODAY?” and takes into account cross-sectional assessment of biologic inflammatory impact on symptoms, signs, endoscopy, histology, and biomarkers.

Disease severity, in comparison, can be described as “What has your patient’s disease course been like over their history since diagnosis?” Measures of disease severity include longitudinal and historical factors that provide a more complete picture of the prognosis and burden of the disease.

He noted that scoring systems for assessing disease activity used in randomized clinical trials “are not what we do in clinical practice.” Using the Mayo score as an example, Dr Sands explained the rating of disease activity is used widely in trials but that in everyday practice, clinicians “can use rectal bleeding and frequency of stool”—just 2 of the criteria—to assess disease activity. “The Crohn’s Disease Activity Index is a complex system but if we boil it down to what is most important, what really drives change, it’s actually the top 2 items: number of daily bowel movements and abdominal pain.”

Because Crohn disease (CD) and ulcerative colitis (UC) “are progressive disease and severity reflects progression over time, it is appropriate to look at disease severity among these patients,” Dr Sands said. Disease severity indices for CD include mucosal lesions; fistulae; abscesses; strictures; prior surgery; daily presence of symptoms; biomarkers for C-reactive protein (CRP), albumin, and hemoglobin; experience with biologics; steroid use; and the impact of the disease on patients’ daily activities. For UC, the indicators also include mucosal lesions; CRP, albumin, and hemoglobin; impact on daily activities; and the presence of daily symptoms, but also include hospitalizations and nocturnal bowel movements.

The advent of treat-to-target approaches to treating IBD have led to a focus on “cycles of care, in which you set a target, such as control of intestinal inflammation, and then do periodic assessments against the baseline over a predefined timeline. If the target is reached you can avoid complications. If not, you alter treatment and continue reassessing,” noted Dr Sands.

Regular assessment by biomarkers or imaging is necessary because “there is poor correlation between symptoms and inflammation, especially in CD,” Dr Sands explained. “The STRIDE study developed evidence-based targets for IBD that combine targets for clinical symptoms with endoscopic targets.”

For UC the clinical target is the resolution of rectal bleeding and normalized bowel habit, while the endoscopic target is resolution of friability and ulceration based on results of flexible sigmoidoscopy or colonoscopy. For CD, the clinical target is resolution of abdominal pain and normalized bowel habits; the endoscopic target is resolution of ulceration on ileocolonscopy. When both targets are achieved, the patient may be considered in complete remission.

“Mucosal healing is increasingly recognized as a treatment target,” and if achieved it can decrease flares, surgeries, and hospitalizations, Dr Sands said. However, he pointed out, the definitions of mucosal healing are not uniform, and a significant proportion of patients may not be able to achieve this target. Further, he explained, endoscopic scores in UC may not “perfectly reflect what’s happening histologically; 1 in 5 patients have a normal endoscopy but still have histologic activity” according to one study.

“You can make this easier in practice by understanding with your pathologist whether the following criteria apply: no more than 5% crypts with neutrophils; no erosions; no ulcers. In such a case, basically you know you’re there; the disease is quiescent,” explained Dr Sands.

“Cross-sectional imaging is an important way to monitor CD activity,” he said, explaining that some features may be missed on colonoscopy that can be imaged by computed tomography enterography. Magnetic resonance imaging is also useful in detecting parameters for CD such as thickening, edema, and ulcers.

Biomarkers have become increasingly important in disease severity assessments for IBD, particularly fecal calprotectin. Dr Sands noted that in the CALM study, “patients being treated to target with biomarkers had far superior outcomes” compared with controls.

Perhaps the most important consideration, Dr Sands said, is that “even if you achieve partial response—only 50% improvement from a baseline score—this does improve outcomes over time” for patients with IBD. “Sometimes in pursuit of perfection, we might make a patient worse, so it is really still an art to know when we’re reached ‘good enough’ as a target,” he said.

—Rebecca Mashaw

Reference:

Sands B. Disease activity assessment: What should we do in clinical practice? Talk presented at: Advances in Inflammatory Bowel Disease 2020 annual meeting; December 9, 2020; Virtual.