Do Muscle Enzyme Changes Forecast Liver Injury in Polymyositis/Dermatomyositis Patients Treated with Methylprednisolone and Methotrexate?

Background: Long-term use of hormones and immunosuppressive agents is necessary for treating polymyositis (PM)/dermatomyositis (DM) but may cause liver damage. At what point do the costs of treatment outweigh the benefits, and how will the breakeven point be determined?

Methods: Serum muscle enzyme changes in 93 PM/DM patients were analyzed over the course of hormone and immunosuppressive agent treatment. From the analysis, a forecasting method was developed to help anticipate possible drug-induced liver injury.

Results: Before treatment, CK levels were frequently elevated and showed correlation with ALT,AST,LDH and CK-MB levels (r=0.682, 0.766, 0.739 and 0.784, respectively). After treatment, all muscle enzyme levels were decreased except ALT (p>0.05). ALT level was positively correlated with CK level (r=0.681) in those patients whose CK level remained abnormal after treatment. Linear regression analysis yielded an equation(CK Level=12.66*ALT Level-136.23) that could predict potential liver damage.

Conclusions: CK level was the most sensitive index of PM/DM and was highly correlated with other serum muscle enzyme levels. An equation capable of predicting potential liver damage according to the correlation of CK and ALT was produced.