RESEARCH - Risk factors for MTX-induced abnormal lab monitoring results in patients with RA

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Journal of Rheumatology

September 2004

Risk Factors for Methotrexate-Induced Abnormal Laboratory Monitoring Results

in Patients with Rheumatoid Arthritis

PETER D. KENT, HARVINDER S. LUTHRA, and CLEMENT J. MICHET Jr

ABSTRACT.

Objective. To determine risk factors for methotrexate (MTX)-induced hepatic

and hematologic laboratory abnormalities in patients with rheumatoid

arthritis (RA).

Methods. Measurements of aspartate aminotransferase (AST), white blood cell

counts, and platelet counts were collected in a database of patients with RA

receiving MTX from 1991 through 2002. Potential risk factors for toxicity

were recorded on each patient.

Results. Four hundred and eighty-one patients were followed for 2,323

person-years of MTX exposure. MTX was discontinued permanently because of

abnormal laboratory test results in 22 patients (4.6%), the majority of whom

(17/22, 77%) had elevated AST values. The body mass index (BMI) was

significantly higher in those patients where MTX was permanently

discontinued than in those in whom it was not (p < 0.03). Independent

predictors of a significantly higher percentage of abnormal AST values were

lack of folate supplementation (p < 0.001) and untreated hyperlipidemia (p <

0.02). Of the 17 patients in whom MTX was discontinued permanently because

of an elevated AST value, 11/17 (65%) had either lack of folate

supplementation or untreated hyperlipidemia. Hypoalbuminemia correlated

independently with an increased percentage of abnormal platelet counts (p <

0.03).

Conclusion. Lack of folate supplementation, untreated hyperlipidemia, and

elevated BMI identified patients receiving MTX at risk for transaminase

elevation, and low serum albumin was a risk factor for thrombocytopenia.

Nonalcoholic fatty liver disease could be the underlying risk factor for

transaminase elevation in patients with hyperlipidemia and obesity. (J

Rheumatol 2004;31:1727-31)

http://www.jrheum.com/subscribers/04/09/1727.html

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