Corticosteroid Monotherapy Is Usually Insufficient Treatment for Idiopathic Inflammatory Myopathy.

Idiopathic inflammatory myopathies (IIM) are a rare group of autoimmune diseases characterized by muscle inflammation. High-dose corticosteroids are conventionally used as the first-line therapy for IIM, but early introduction of noncorticosteroid immunosuppressive agents has become increasingly common in recent years despite a paucity of compelling evidence to support this. Here, we systematically analyze therapeutic practice patterns of IIM in a large municipal safety net medical center. We conducted a retrospective chart review of all adult patients attending rheumatology clinics at the Cook County Health and Hospital Systems from 2006 to 2011 with a diagnosis of IIM. Data collected included patient demographics, diagnosis, immunosuppressive therapies, serial serum creatine kinase (CK) measurements, and serial muscle strength testing. One hundred eight patients fulfilled eligibility criteria. The mean duration of follow-up was 62 months (range, 1-351 months). At presentation, the mean strength in the weakest muscle group was rated as 3.6 out of 5 (range, 1-5; SD 0.9), the mean initial CK was 4720 U/L (range, 23-38, 461; SD 6, 795), and initial mean prednisone dosage was 48 mg/d (range, 0-100, SD 22). At the end of the follow-up period, mean strength in the weakest muscle group was 4.6 out of 5 (range, 2-5; SD 0.7), mean peak CK was 412 (24-7533; SD 875), and the mean prednisone dosage was 12.7 mg (0-80; SD 17.5). Only 15 patients (14%) received exclusively corticosteroid monotherapy during the follow-up period. Ninety-three patients (86%) received additional immunosuppressive agents. Over the course of their illness, only a minority of patients in our cohort of IIM patients was treated with corticosteroids alone. It is unlikely we will determine optimal therapy in the absence of a large controlled study comparing corticosteroids versus a combination regimen, but it seems that rheumatologists favor addition of second-line immunosuppressive agents.

Serum transaminases are frequently elevated at time of diagnosis of idiopathic inflammatory myopathy and normalize with creatine kinase.

INTRODUCTION: Despite multiple reports of elevated transaminases in muscle injury, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) are not always considered indicators of muscle damage. The purpose of this study was to examine the relationship between serum AST, ALT, and creatine kinase (CK) levels at time of diagnosis of idiopathic inflammatory myopathy (IIM) and at the time of CK normalization. METHODS: We conducted a retrospective chart review of all adult patients attending rheumatology clinics at a county hospital with a diagnosis of IIM. Data collected included patient demographics, serial CK measurements, and serial serum transaminase measurements. RESULTS: We identified 85 patients with IIM. At myositis presentation, 75 (88%) had CK above the upper limit of normal (ULN), 72 (85%) had AST above the ULN, and 68 (80%) had ALT above the ULN. The average CK was 5302 U/L (range, 23-38,461 U/L [SD, 7096]), average AST 215 U/L (range, 16-1270 [SD, 227]), and average ALT 137 U/L (range, 10-621 [SD, 137]). The average AST and ALT at first available normalized CK was 26 U/L (range, 9-139 [SD, 18]) and 26 U/L (range, 5-96 [SD, 19]). We found a strong correlation between CK and AST (r= 0.832; P < 0.001) and ALT (r = 0.775; P < 0.001) at initial presentation and also at the time of peak CK levels (r = 0.874 [P < 0.001] and r = 0.842 [P < 0.001], respectively). CONCLUSIONS: In our series, we found a strong correlation between CK and serum transaminases. Serum transaminases were elevated in 80% of patients at the time of presentation and normalized in 85% of the patients at the time of CK normalization. Appropriate recognition of these laboratory changes in IIM may help reduce unnecessary hepatic evaluation, delayed diagnosis, unnecessary avoidance of second line immunosuppressants, and misdiagnosis of primary liver disease.