Background/Aim To define practical use and to specify the ideal method for monitoring the liver toxicity of MTX in the management of psoriasis.
Objective To systematically review the literature regarding treatment modalities with methotrexate (MTX) in psoriasis, risk of MTX-mediated liver fibrosis and monitoring of hepatic toxicity.
Methods A systematic literature search was carried out in Medline, Embase and Cochrane Library databases from 1980 to 2010 searching for randomized controlled trials and observational studies on methods of administering MTX in psoriasis and risk factors and assessment of liver toxicity. We limited the literature search to articles on human subjects over 19 years of age, articles in English or French on psoriasis and articles including psoriatic arthritis and original data.
Results Among 949 references identified, 23 published studies were included. There were no studies focusing directly on the question of MTX treatment modalities. Treatment outcome appears to be dose dependent. A single study in rheumatoid arthritis showed the slightly superior efficacy of subcutaneous administration vs. oral dosing with a similar safety profile. Combination with folic acid may decrease the efficacy of MTX while improving tolerability. The extreme variability of the incidence of hepatic fibrosis in the literature does not allow the risk of hepatic fibrosis to be quantified. Type 2 diabetes and obesity, were associated with a significant increased risk of liver fibrosis. Hepatitis B and C and alcohol consumption were associated with a modest and non-significant increased risk of liver fibrosis. Procollagen III for detection of hepatic fibrosis dosing was the most extensively validated method to monitor liver fibrosis showing a sensitivity of 77.3% and a specificity of 91.5%. The Positive Predictive Value and Negative Predictive Value fluctuated depending on the prevalence of hepatic fibrosis. The sensitivities of the FibroTest and the fibroscan were of 83 and 50%, respectively, with specific features amounting to 61 and 88% respectively.
Conclusions Based on expert experience, the starting dose of MTX is between 5 and 10 mg/week for the first week. Fast dose escalation is recommended in order to obtain a therapeutic target dose of 15–25 mg/week. The maximum recommended dose is 25 mg/week. A folic acid supplement is necessary. The initiation of treatment by oral administration is preferred. In cases where inadequate response is obtained or in the event of poor gastrointestinal tolerance, subcutaneous dosing can be proposed at the same dose. Published data do not confirm the incidence of hepatic fibrosis. Type 2 diabetes and obesity appear to be significant risk factors in fibrosis. A combination of FibroTests and fibroscans together with measurement of the type III serum procollagen aminopeptide seem to be ideal method for monitoring liver toxicity.