RESEARCH - Long term safety of MTX: discontinuation is unusual and rarely the result of laboratory abnormalities

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ls of the Rheumatic Diseases 2005;64:207-211

© 2005 by BMJ Publishing Group Ltd & European League Against Rheumatism

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EXTENDED REPORT

Long term safety of methotrexate in routine clinical care:

discontinuation is unusual and rarely the result of laboratory

abnormalities

Y Yazici 1, T Sokka 2, H Kautiainen 3, C Swearingen 4, I Kulman 5, T Pincus 4

1 Brooklyn Heights Arthritis Associates, Long Island College Hospital,

Brooklyn, New York, USA

2 Vanderbilt University, Nashville, Tennessee, and Jyväskylä Central

Hospital, Jyväskylä, Finland

3 Rheumatism Foundation Hospital, Heinola, Finland

4 Vanderbilt University, Nashville, Tennessee

5 Mount Sinai School of Medicine, New York

Accepted 9 May 2004

ABSTRACT

Objective: To analyse patients with rheumatoid arthritis, treated with

methotrexate in a weekly academic rheumatology clinic over 13 years,

for continuation of courses and reasons for discontinuation.

Methods: All 248 patients with an analysable longitudinal course who

took methotrexate in standard care between 1990 and 2003 were studied.

Continuation of courses was analysed using life tables. All abnormal

and severely abnormal values for aspartate aminotransferase (AST) >40

U/l, >80 U/l, albumin <35 g/l, <30 g/l, white blood cell (WBC) count

<4.0x109/l, <3.0x109/l, and platelet count <150x109/l, <100x109/l,

were identified. Responses of the clinician and subsequent laboratory

values were reviewed.

Results: Over 1007 person-years, the probability of continuing

methotrexate over five years was 79% (95% confidence interval, 72% to

84%). Severe laboratory abnormalities occurred in 2.9 per 100

person-years, specifically 0.9 for AST >80 U/l, 1.1 for albumin <30

g/l, 0.7 for WBC <3.0x109/l, and 0.3 for platelets <100x109/l. No

severe laboratory abnormality progressed to further severity or

clinical disease. Permanent discontinuations of methotrexate occurred

in 46 patients (19%), 26 (10% of all patients) for adverse effects, 15

(32.6%) for inefficacy; only two discontinuations resulted from

laboratory abnormalities, both of WBC, possibly from other sources.

Conclusions: Methotrexate was associated with a high rate of

continuation, and few clinically significant laboratory abnormalities.

Discontinuation primarily reflected clinical rather than laboratory

findings. Vigilance for methotrexate toxicity is required but

methotrexate appears among the safest treatments for rheumatoid

arthritis.

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