Final answer:
The adverse effect that occurs at a higher rate in patients receiving the combination of infliximab and azathioprine is hepatitis.
Step-by-step explanation:
In patients receiving the combination of infliximab and azathioprine, the adverse effect that occurs at a higher rate is hepatitis. Hepatitis refers to inflammation of the liver, and it can have various causes, including viral infections. Other systemic disorders such as diabetes mellitus, malnutrition, and HIV infection can also lead to hepatitis. Immunossuppressive treatments and prolonged critical illness can be contributing factors as well.