A 64-year-old man is having difficulty getting out of a chair. He has lost 15 lb and feels tired all the time. On examination, there is a blue purple rash on his eyelids and knuckles, and muscle strength in his proximal muscles is rated 4 out of 5. His creatinine kinase (CK) level is elevated and he is started on prednisone. Which of the following is the most important in monitoring response to therapy?
testing of muscle strength sedimentation rates urine transaminase enzymes EMG