Low infliximab serum trough levels and anti-infliximab antibodies are prevalent in rheumatoid arthritis patients treated with infliximab in daily clinical practice: results of an observational cohort studyReport as inadecuate




Low infliximab serum trough levels and anti-infliximab antibodies are prevalent in rheumatoid arthritis patients treated with infliximab in daily clinical practice: results of an observational cohort study - Download this document for free, or read online. Document in PDF available to download.

BMC Musculoskeletal Disorders

, 13:184

First Online: 24 September 2012Received: 21 October 2011Accepted: 19 September 2012

Abstract

BackgroundTo get insight in the prevalence of high, or low-no serum infliximab trough levels in patients with low disease activity and if serum trough levels are stable and reliable longitudinally we conducted a prospective cohort study

MethodsIn a longitudinal, observational cohort of RA patients treated with infliximab for at least 6 months, treatment interval, DAS28, infliximab trough levels and anti-infliximab antibodies were assessed. Prevalence of low <1 mg-l and high >5 mg-l infliximab serum trough levels and anti-infliximab antibodies was recorded. Relationship of a change in anti-infliximab antibodies and treatment interval was described. Reliability of consecutive infliximab serum trough levels and anti-infliximab antibodies in patients with stable DAS28 and treatment was analysed with Spearman correlation and kappa-analysis.

Results147 patients with a mean disease duration of 11 years sd7 and DAS28 of 3.5 sd1.3 at baseline were followed during 1.5 years. Inter-individual variability in infliximab levels in patients with low DAS28 was high median 1.4 mg-L, IQR 3.35, with 31% 95%CI: 20-42% having low <1 mg-L and 14% 95%CI 5–22 high trough levels >5 mg-L. Interestingly also in RA patients with DAS28 ≤ 3.2, anti-infliximab antibodies were found in one-third of the patients, with half of them having antibodies every visit during a median of more than one year. Agreement for consecutive measurements of serum trough levels and anti-infliximab antibodies was high in stable patients: r = 0.97 p = 0.00001 and kappa = 1.0 SE 0.14 Anti-infliximab antibody appearance was influenced by interval increases relative risk RR 5.2, 2.6-10.7, but patients still showed low infliximab levels.

ConclusionsLow and high infliximab serum trough levels are prevalent, interestingly also in patients with low disease activity. Consecutive measurements of serum trough levels and anti-infliximab antibodies are reliable in stable patients. These test could be used to lower or stop infliximab in selected patients.

KeywordsRheumatoid arthritis Infliximab Therapeutic drug monitoring Serum trough levels Anti-infliximab antibodies Low disease activity AbbreviationsAUCArea under the curve

CIConfidence interval

DAS28Disease activity score of 28 joints

LoALimits of agreement

MICMinimal inhibitory concentration

MRECMedical Research Ethics Committee

MTXMethotrexate

RARheumatoid arthritis

RRRelative risk ratios

SDStandard deviation

SEStandard error.

Electronic supplementary materialThe online version of this article doi:10.1186-1471-2474-13-184 contains supplementary material, which is available to authorized users.

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Author: Aatke van der Maas - Bart JF van den Bemt - Gertjan Wolbink - Frank HJ van den Hoogen - Piet LCM van Riel - Alfons A den

Source: https://link.springer.com/







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