Antibiotic use may increase the risk of inflammatory bowel illness (Crohn’s disease and ulcerative colitis) in people over 40, according to a study published online in the journal Gut. The risk seems to be cumulative and greatest 1-2 years after use and for those antibiotics targeting gut infections, the findings indicate.

Mounting evidence suggests that environmental factors are likely implicated in the development of inflammatory bowel disease (IBD). Globally, close to 7 million people have the condition, with this number expected to rise over the next decade, say the researchers. One factor associated with IBD risk in younger people is the use of antibiotics, but it’s not clear if this association might also apply to older people. To explore this further, the researchers drew on national medical data from 2000 to 2018 for Danish citizens aged 10 upwards who hadn’t been diagnosed with IBD. They specifically wanted to know if the timing and dose of antibiotic might be important for the development of IBD, and whether this varied by IBD and antibiotic type.

More than 6.1 million people were included in the study, just over half of whom were female. In total, 5.5 million (91%) were prescribed at least one course of antibiotics between 2000 and 2018. During this period, some 36,017 new cases of ulcerative colitis and 16,881 new cases of Crohn’s disease were diagnosed.

Overall, compared with no antibiotic use, use of these drugs was associated with a higher risk of developing IBD, regardless of age. But older age was associated with the highest risk.

Those aged 10-40 were 28% more likely to be diagnosed with IBD; 40-60 year olds were 48% more likely to do so, while the over 60s were 47% more likely to do so.

The risks were slightly higher for Crohn’s disease than they were for ulcerative colitis: 40% among 10-40 year olds; 62% among 40-60 year olds; and 51% among the over 60s.

The risk seemed to be cumulative, with each subsequent course adding an additional 11%, 15%, and 14% heightened risk, according to age band.

The highest risk of all was observed among those prescribed 5 or more courses of antibiotics: 69% heightened risk for 10-40 year olds; a doubling in risk for 40-60 year olds; and a 95% heightened risk for the over 60s. Timing also seemed to be influential, with the highest risk for IBD occurring 1-2 years after antibiotic exposure, with each subsequent year thereafter associated with a lowering in risk.

Specifically, among 10-40 year olds IBD risk was 40% higher 1-2 years after taking antibiotics compared with 13% 4-5 years later. The equivalent figures for 40-60 year olds were 66% vs 21% and for the over 60s 63% vs 22%.

Source: ANI