Success and safety of high infliximab trough levels in inflammatory bowel disease

<p><b>Objective:</b> A prospective trial suggests target infliximab trough levels of 3–7 μg/mL, yet data on additional therapeutic benefits and safety of higher trough levels are scarce.</p> <p><b>Aim:</b> To explore whether high infliximab trough levels (≥7 μg/mL) are more effective and still safe.</p> <p><b>Material and methods:</b> In this cohort study of 183 patients (109 Crohn’s disease and 74 ulcerative colitis) on infliximab maintenance treatment at a tertiary referral center we correlated fecal calprotectin and C-reactive protein to trough levels (426 samples) at different time points during treatment. Rates of infections were compared in quadrimesters (four-month periods) with high trough levels to quadrimesters with trough levels <7 μg/mL during 420 patient-years.</p> <p><b>Results:</b> Fecal calprotectin and C-reactive protein (median [interquartile range]) were lower in patients with high trough levels (fecal calprotectin 66 mg/kg [30–257]; C-reactive protein 3 mg/L [3–3]) compared to trough levels below 7 μg/mL (fecal calprotectin 155 mg/kg [72–474]; C-reactive protein 3 mg/L [3–14.5]) (<i>p</i> < .001). High trough levels were superior also after excluding samples with trough levels <3 μg/mL from analysis. No differences in rates of infections were observed in quadrimesters with high trough levels (16/129 [12.4%]) compared to quadrimesters with trough levels <7 μg/mL (32/344 [9.3%]) (<i>p</i> = .32). Maintaining high trough levels resulted in 32% (interquartile range: 2–54%) increase of infliximab consumption.</p> <p><b>Conclusion:</b> High infliximab trough levels provide better control of inflammation in inflammatory bowel disease without increasing the risk of infection.</p