Ulcerative colitis is usually thought of as a disease of the bowel. Yet a large study from the United States has found that people with the condition may also be more likely to have a form of lung disease than people with Crohn’s disease.
The finding highlights how illnesses that begin in the digestive system can sometimes affect the whole body.
Ulcerative colitis and Crohn’s disease are the two major forms of inflammatory bowel disease, or IBD. They are long-lasting conditions in which the body’s defense system drives repeated inflammation in the digestive tract. Symptoms can improve for a time and then return during periods when the disease becomes more active.
Ulcerative colitis mainly damages the inner lining of the colon and rectum. Crohn’s disease can affect deeper layers of the bowel and can appear in different areas of the digestive tract. Both conditions can cause diarrhea, abdominal pain, bleeding, tiredness and weight loss.
But IBD is not simply a gut problem. Some patients develop painful joints, skin conditions, eye inflammation or liver problems. Scientists have also reported lung problems in people with IBD, although the size of that risk and the people most likely to be affected have remained unclear.
Researchers led by Sneh Parekh, D.O., at the University of Florida College of Medicine in Jacksonville examined one particular problem called interstitial lung disease. ILD affects the tissue that supports the tiny air sacs inside the lungs. Inflammation or scarring in this tissue can make the lungs less flexible and interfere with the movement of oxygen into the bloodstream.
Some people with ILD develop a persistent dry cough or become breathless during activities that once felt easy. Others may have only mild symptoms at first. Because breathing problems are common in many illnesses, the underlying lung disease may not always be recognized quickly.
The research team analyzed records from 8,865 patients with inflammatory bowel disease. These patients received care at two major specialist medical centers in the southeastern United States from 2012 through 2022. The researchers examined how often ILD appeared and whether the pattern differed between Crohn’s disease and ulcerative colitis.
They found that 4.6% of the patients had both IBD and interstitial lung disease. The rate of ILD was significantly higher among patients with ulcerative colitis than among those with Crohn’s disease. Age, sex and other basic demographic features were generally similar when the researchers compared the ulcerative colitis-lung disease group with the Crohn’s-lung disease group.
The patients with both bowel and lung disease stood out in other ways. Compared with people who had IBD alone, they were older and used hospital services more often. They had more emergency department visits and hospital admissions, suggesting that the combination of illnesses may be linked to more complicated health needs.
Steroid use was also more common among people with both conditions. These medicines can be valuable because they quickly reduce inflammation during an IBD flare, but doctors try to avoid unnecessary long-term use because steroids can weaken bones, increase infection risk and cause other problems. The study also found lower use of mesalamine among patients with IBD and ILD.
Another result involved patients from minority groups. The researchers found a higher level of other health conditions among minority patients with IBD and ILD than among White patients. This finding raises questions about differences in health, treatment and access to medical care that cannot be answered by this study alone.
Why might a bowel disease be connected to the lungs? One possibility is that the same abnormal immune activity that causes inflammation in the intestines may sometimes affect lung tissue. The digestive tract and airways also share some biological features, but researchers are still working to understand the exact connection.
There are other explanations that doctors must consider. Some medicines used for IBD can occasionally affect the lungs, while infections and unrelated lung diseases can produce similar symptoms. This means that a cough or breathing difficulty in someone with IBD needs careful assessment rather than an automatic assumption about its cause.
The study was published online July 24 in the journal Crohn’s & Colitis 360. The authors said the greater health care burden seen among patients with both conditions supports considering earlier recognition of lung disease in people with IBD. They suggested that ulcerative colitis patients could receive particular attention if health systems do not have enough resources to screen everyone.
There are good reasons to take the findings seriously. The researchers studied a large number of patients and used a decade of information from real clinical practice. The clear difference between ulcerative colitis and Crohn’s disease gives researchers a useful question to investigate in future studies.
At the same time, the study cannot tell us whether ulcerative colitis itself causes ILD. Because the researchers looked at existing patient information rather than randomly assigning treatments or exposures, other factors may partly explain the association. Patients at large specialist centers may also be sicker than the average person living with IBD.
More research is needed to learn which patients are truly at greatest risk and whether routine lung screening improves health outcomes. Researchers also need to separate lung problems caused by IBD itself from those related to medicines, infections, smoking or other diseases. That information would help doctors avoid unnecessary testing while finding serious lung disease earlier.
For now, the study broadens the way people can think about inflammatory bowel disease. A person with ulcerative colitis or Crohn’s disease should not assume that every cough is connected to IBD, but ongoing breathlessness or a persistent dry cough deserves medical attention. Recognizing that IBD can affect organs beyond the intestines may help patients and doctors spot important problems sooner.
Source: University of Florida.
