Immune-mediated necrotizing myopathy (IMNM) is a kind of myositis with a refractory pattern and a dismal prognosis. For a study, researchers sought to offer a single large center experience of intravenous immunoglobulin (IVIg) outcomes for patients with IMNM utilizing longitudinally collected data. From 2014 to 2019, the University of Pittsburgh longitudinally investigated 4 of the 6 myositis core set assessments at baseline, 3 and 6 months following IVIg on 20 adult IMNM patients. They looked at core set measurements, prednisone dosage, side effects, and the “restricted” ACR/EULAR 2016 myositis response criteria. A paired t-test was used to evaluate the mean differences in CK and manual muscle testing (MMT-8). At 6 months of IVIg, a clinically meaningful response was defined as a greater than 10% absolute improvement in MMT-8 and a greater than 50% absolute reduction in serum CK.
In IMNM patients, intravenous immunoglobulin therapy was linked with considerable improvement, with 85% of patients fulfilling clinically meaningful response criteria. At 6 months, the median (interquartile range) relative percent improvement in CK level was 96%(85% –98%) and in MMT was 29% (14% –36%).
At 6 months, there was a considerable reduction in the mean (SD) dosage of prednisone with few side effects. Furthermore, according to the ACR/EULAR 2016 myositis response criteria, the majority (13/14) of patients improved with IVIg.
Early use of IVIg in adult IMNM should be explored based on objective, meaningful improvement in MMT-8 and CK, as well as a significant reduction in prednisone dosages with tolerable tolerability.