Background: Both muscle-related complaints and elevated serum creatine kinase (CK) levels have been reported in patients with inflammatory bowel disease (IBD) treated with infliximab (IFX), mainly as case reports. The aim of this study was to investigate the effect of IFX therapy on serum CK levels in a cohort of Greek IBD patients.
Methods: Demographic, clinical and laboratory data of consecutive IBD patients on maintenance treatment with IFX and a matched control group of IBD patients without any use of biological treatment were retrospectively analyzed. All patients and controls had at least 3 CK measurements, with at least 10 days interval among them and we used the mean CK value for the analysis. Data of all patients with elevated mean CK were reviewed for persistent muscle complaints not associated with exercise and for the existence of other causes of persistent hyperCKemia (muscular damage, use of statins or thyroxine, coronary heart disease and kidney disease).
Results: The IFX-treated IBD patient group included 88 individuals [65 Crohn's Disease (CD), 23 ulcerative colitis (UC), mean age 42.5±14.7 years, 62.5% men, median (IQR) duration of IFX treatment 26 (13–71) months]. Eighty-eight patients without treatment with any biological agents formed the control group (54 CD, 34 UC, mean age of 49.7±16.1 years, 61.2% men). Twenty-seven IFX-treated patients (30.7%) had elevated mean serum CK levels (>180 U/L) compared to 9 (10.2%) in the control group (p=0.0002). Other possible causes of persistent hyperCKemia were identified in 7 of the 27 (25.9%) patients of the IFX group compared to 2 of the 9 (22.2%) of the control group. When those patients were excluded, the difference among the two groups remained significant (p=0.01). The median (range) CK value in the IFX group was 123 U/L (40–1145), which was significantly higher than that of the control group (81 U/L, 14–1034, p<0.0001). There were no correlations between elevated CK and the disease type (CD vs UC) or the clinical characteristics of the disease. In the logistic regression analysis the presence of hyperCKemia after adjustment for age, disease type and existence of other causes of elevated CK was independently associated with the use of IFX [OR 2.92 (1.63–9.45) p=0.002]. No patient with hyperCKemia in both groups reported any persistent symptoms of myopathy.
Conclusions: More than 30% of IBD patients under maintenance treatment with IFX present asymptomatic persistent and treatment related hyperCKemia. Serum CK levels are significantly higher in IFX treated patients compared to patients without any biological treatment. Further relevant prospective investigation is needed.