RESEARCH - Factors associated with toxicity, final dose, and efficacy of MTX in patients with RA

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Factors associated with toxicity, final dose, and efficacy of methotrexate

in patients with rheumatoid arthritis

M Hoekstra1, A E van Ede2, C J Haagsma1, M A F J van de Laar1, T W J

Huizinga3, M W M Kruijsen1 and R F J M Laan2

1 Department of Rheumatology, Medisch Spectrum Twente, Enschede, The

Netherlands

2 Department of Rheumatology, University Medical Centre Nijmegen, The

Netherlands

3 Department of Rheumatology, Leiden University Medical Centre, The

Netherlands

Objective: To study factors associated with toxicity, final dose, and

efficacy of methotrexate (MTX) in patients with rheumatoid arthritis (RA).

Methods: Data were used from a randomised clinical 48 week trial on 411

patients with RA all treated with MTX, comparing folates and placebo.

Logistic regression was used to study the relation between baseline

variables and various dependent factors, including hepatotoxicity (alanine

aminotransferase 3xupper limit of normal), MTX withdrawal, final MTX dose 15

mg/week, and MTX efficacy.

Results: Addition of folates to MTX treatment was strongly related to the

lack of hepatotoxicity. Next to this, high body mass index was related to

the occurrence of hepatotoxicity. Prior gastrointestinal (GI) events and

younger age were related to the adverse event, diarrhoea. Hepatotoxicity and

GI adverse events were the main reason for MTX withdrawal, which in turn was

associated with the absence of folate supplementation, body mass index,

prior GI events, and female sex. Renal function (creatinine clearance 50

ml/min) was not associated with toxicity. Reaching a final dose of MTX of 15

mg/week was related to folate supplementation and the absence of prior GI

events. Efficacy of MTX treatment was associated with low disease activity

at baseline, male sex, use of non-steroidal anti-inflammatory drugs

(NSAIDs), and lower creatinine clearance.

Conclusions: MTX toxicity, final dose, and efficacy are influenced by folate

supplementation. Baseline characteristics predicting the outcome of MTX

treatment are mainly prior GI events, body mass index, sex, use of NSAIDs,

and creatinine clearance.

http://ard.bmjjournals.com/cgi/content/abstract/62/5/423

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