Spotlight on IBD's associations with other diseases

Two new studies highlighted elevated risks of other diseases among patients with inflammatory bowel disease (IBD).

One study, published by the American Journal of Gastroenterology on Aug. 4, used a nationwide cohort of 85,705 patients with IBD in Sweden who were diagnosed between 1969 to 2019 and followed until 2021 to look at their risk for interstitial lung disease (ILD). Each IBD patient was matched with up to five healthy controls (n=412,677). Over a median follow-up of 14 years, 0.51% of the IBD group were diagnosed with ILD compared to 0.30% of healthy controls, for a 48% greater relative risk. Findings were consistent in ulcerative colitis and Crohn's disease. In a secondary analysis, patients with IBD were matched with their own siblings who did not have IBD, and the risk of ILD with IBD was even higher (adjusted hazard ratio [HR], 1.81; 95% CI, 1.43 to 2.27).

“While it is well established that IBD can be co-morbid with other immune-mediated inflammatory disorders, such as spondyloarthritis, this is the largest study to our knowledge to establish a relationship between IBD and ILD,” said the study authors. They highlighted the finding that older age and female sex were associated with greater risk of ILD in IBD patients. The authors also noted that ILD is often diagnosed late and said it is possible that earlier diagnosis and treatment of the disease could reduce morbidity and mortality. “These data also support clinicians maintaining a higher index of suspicion for ILD in their IBD patients with pulmonary symptoms,” they wrote.

The other study, published by Clinical Gastroenterology and Hepatology on July 22, investigated the associations among IBD, colorectal cancer (CRC), and primary sclerosing cholangitis (PSC). It also used the Swedish registry of IBD patients, this time those diagnosed from 1969 to 2014, again each matched with five controls. Patients with IBD were found to have a significantly higher risk of CRC (HR, 1.83 [95% CI, 1.72 to 1.96]; P<0.001). Risk was highest in patients who also had PSC, but it decreased over the study period. Patients who had PSC and were diagnosed with IBD by 20 years of age had a particularly high incidence of CRC (rate ratio, 74.97 [95% CI, 44.7 to 126.1]; P<0.001). In patients with PSC and IBD, CRC was more commonly in the cecum/ascending, transverse, and descending colon; synchronous cancer was also more common.

“This corroborates previous studies reporting an increased risk of gastrointestinal cancers and death in patients with childhood and adolescent onset IBD, emphasizing the need for awareness of the risks,” especially in young patients with PSC, the study authors said. They suggested that the findings be considered in monitoring and counseling of IBD patients, including “regarding type of resection for cancer and choice of restorative surgery.”