Potential hepatotoxicity associated with disease-modifying antirheumatic drugs (DMARDs) requires laboratory monitoring. In patients with rheumatoid arthritis (RA) or psoriatic arthritis (PsA), the incidence of elevated alanine aminotransferase/aspartate aminotransferase (ALT/AST) enzymes associated with methotrexate (MTX), leflunomide (LEF) and MTX+LEF versus other DMARDs was examined.
Patients with RA and PsA enrolled in the Consortium of Rheumatology Researchers of North America (CORRONA) initiating DMARDs were identified. Abnormalities were identified when either was 1- or 2-fold times above the upper limits of normal (ULN). Odds ratios (OR) between MTX/LEF dose and elevated ALT/AST enzymes were estimated using generalised estimating equations. Interaction terms for use of MTX+LEF quantified the incremental risk of the combination compared with each individually.
Elevated ALT/AST levels (>1x ULN) occurred in 22%, 17%, 31% and 14% of patients with RA receiving MTX, LEF, MTX+LEF or neither, respectively; elevations were 2.76-fold (95% CI 1.84 to 4.15) more likely in patients with PsA. Elevations >2x ULN occurred in 1-2% of patients on MTX or LEF monotherapy compared with 5% with the combination. After multivariable adjustment and compared with either monotherapy, the combination of MTX and LEF was associated with a greater risk according to MTX dose used as part of the combination: MTX 10-17.5 mg/week, OR 2.91 (95% CI 1.23 to 6.90); MTX > or =20 mg/week, OR 3.98 (95% CI 1.72 to 9.24).
Abnormal ALT/AST levels developed in 14-35% of patients with RA or PsA initiating DMARD therapy. The risks were incrementally greater in those with PsA and in those receiving MTX (> or =10 mg/day) + LEF. These findings should help inform monitoring for potential hepatotoxicity in these patient populations.