Taking antibiotics is linked to an increased risk of developing inflammatory bowel disease (IBD), a large population-based cohort study of older adults suggests.
Building on previous research linking antibiotic use with IBD onset in younger adults, researchers used data from Danish health registries to review antibiotic exposure among 2.3 million patients aged 60 years and older who had no previous diagnosis of IBD.
Between 2000 and 2018, they recorded 10,773 new cases of ulcerative colitis and 3,825 new cases of Crohn’s disease, according to the research due to be presented at the Digestive Disease Week (DDW) congress in San Diego, US, later this week.
Overall, researchers found any antibiotic exposure was associated with a 65% risk of developing IBD, with researchers also seeing a dose-response relationship.
After one prescription for antibiotics, patients were 27% more likely than those with no antibiotic use to be diagnosed with IBD, rising to a 2.3 fold increased risk among those older adults who had five or more antibiotic prescriptions.
Timing of the exposure affected risk, with the risk of developing IBD highest in those who had received antibiotics one to two years prior to their diagnosis, but the risk persisted even in those who had received antibiotics five to 10 years prior to diagnosis.
To reduce confounding from prescriptions issued for symptoms of as-yet undiagnosed IBD, the researchers did not include antibiotic exposure in the year before a diagnosis.
The association was found for all types of antibiotic classes, except for nitrofurantoin, commonly used for urinary tract infections.
However, researchers noted it was the antibiotics most used for gastrointestinal infections which were the most likely to be associated with a new IBD diagnosis.
Lead author Dr Adam S. Faye, assistant professor of medicine and population health at NYU Grossman School of Medicine, US, said that the incidence of IBD was known to be rising in older adults and environmental factors were thought to be at play.
'When you look at younger patients with new diagnoses of Crohn’s disease and ulcerative colitis, there’s generally a strong family history. But in older adults, it seems that something in the environment is triggering it,' he said.
'These data support the idea that perhaps antibiotics are doing something to the gastrointestinal microbiome. Even antibiotics that aren’t used to treat gastrointestinal pathogens but still impact the microbiome have a risk.'
It was possible that antibiotics were being prescribed for underlying infections that in themselves could be contributing IBD, he noted, but he hoped future microbiome studies could help to distinguish the potential triggers.
While the study findings added to the arguments for antibiotic stewardship, he noted they were not a reason to withhold antibiotics when needed.
'Antibiotic stewardship is important; but avoiding antibiotics at all costs is not the right answer either,' he said.
The study might also help to diagnose IBD in older adults with gastrointestinal symptoms, which could be difficult due to the broad differential.
'If you know that patients have taken courses of antibiotics recently, perhaps IBD moves a bit higher on your differential,' he said.
The study was conducted in partnership with the Danish National Center of Excellence PREDICT program.