Background: Medical treatment of inflammatory bowel disease (IBD) is becoming more
and more complex, as several classes of immuno-modulating drugs (IMD) are often used
simultaneously. Thus, the probability of adverse effects is greatly increased. Most studies
reporting on adverse effects focus on single therapy, and studies providing a global survey
of side effects for multiple treatments are lacking. Aim: To assess the type and frequency
of adverse events in IBD patients treated with single and multiple IMD therapy. Methods:
Analysis of data from the Swiss IBD Cohort Study (SIBDCS) that collects data on a large
sample of IBD patients from hospitals and private practices across Switzerland. The following
IMD categories were analyzed: 5-ASA, azathioprine (Aza), 6-mercaptopurine (6-MP), methotrexate
(MTX), anti-TNF (infliximab, adalimumab, certolizumab-pegol), cyclosporine, tacrolimus,
and steroids. The following side effects were assessed: hepatitis, pancreatitis, leucopenia,
thrombopenia, nephritis, allergic reaction, pneumonitis, infections (including tuberculosis),
osteoporosis, abdominal pain/diarrhea (unrelated to IBD activity), cataract, diabetes, exanthema,
hirsutism, lupus-like syndrome, myalgias, depression/psychosis, tumor development.
Results: A total of 1,961 patients were analyzed (977 [50%] female, mean age 42.1 ± 14.4
years): 1,119 with Crohn's disease (CD), 800 with ulcerative colitis (UC), and 42 with
indeterminate colitis (IC). Three-hundred eighteen (16.2%) patients were not treated with
any of the above-mentioned medications, while 650 (33.2%), 569 (29%) and 424 (21.6%)
patients had one-, two-, and three- or more- IMD therapy, respectively. Of the 1,643 patients
treated with IMD, 535 (32.6%) patients reported at least one side effect. We found a
significant correlation between the number of drugs used by a patient and the frequency
of side effects (17.4% side effects for one drug, 29% for 2 drugs, and 60.6% for three or
more drugs, p < 0.001). The frequency of side effects for the different IMD classes were as
follows: 5-ASA (n = 980 treated patients) 10.8%, Aza/6-MP (n = 636) 51.9% (pancreatitis
in 57 = 9%, hepatitis in 17 = 2.7% of treated patients), MTX (n = 146) 42.5% (hepatitis
in 4 = 2.7% of treated patients), anti-TNF (n = 255) 23.1%, cyclosporine (n = 49) 10.2%,
tacrolimus (n = 5) 20%, steroids (systemic or topical, n = 1,150) 9.6%. Conclusion: IBD
treatment is associated with a significant number of side effects. A direct correlation between
the number of IMD used simultaneously and the frequency of side effects was observed.
The results of this study indicate that treating physicians should be vigilant for the occurrence
of side effects in IBD patients under single and/or multiple drug therapy.