Few environmental determinants of Crohn’s disease are well established.
There is some data implicating antibiotic use as a risk factor. However, these data are derived from studies which used questionnaires to assess antibiotic use, making them susceptible to recall bias.
In this study, physicians from England explored the relationship between Crohn's disease and antibiotics using prospectively gathered data.
The team selected incident cases of Crohn’s disease from the General Practice Research database. For each case there was at least 5 years of data prior to diagnosis.
Controls with five years of complete data were randomly selected.
The team also assessed smoking, drug prescriptions, age, sex, and a variety of symptoms and diagnoses that might be indicative of occult Crohn’s disease.
The physicians were able to evaluated 587 cases of Crohn’s disease and 1460 controls.
The team found that antibiotic use 2 to 5 years before Crohn's diagnosis occurred in 71% of cases compared with 58% of controls.
Furthermore, the median number of antibiotic courses was 2 for the cases and 1 for the controls.
Once the physicians adjusted for age, sex, smoking, and use of other drugs, they determined that antibiotic use had an odds ratio of 1.32.
|Antibiotic use had an odds ratio of 1.32.|
However, the team was unable to show specificity to any subgroup of antibacterials.
In addition, associations similar to that with antibiotics were also found with oral contraceptives, cardiovascular, and neurological drugs.
Dr Card's team concluded, "We found a statistically significant association between Crohn’s disease and prior antibiotic use".
"This cannot be explained by recall bias, but due to lack of specificity it is unclear whether it is causal".