Is the efficacy and dose same for subcutaneous vs intravenous IVIGs being used for dermatomyositis?

Thank you for the very interesting question:

When considering the best answer, there is a bit of background I think is important to keep in mind. (I'll put my final thoughts about dosing at the end of this background)

• First and foremost, although IVIG has been used as a de facto treatment for multiple subtypes and manifestations of autoimmune myositis for over 30 years, it is only recently that IVIG has been formally robustly evaluated enough to gain FDA-approval for a particular formulation of IVIG for dermatomyositis (on the basis of the ProDERM trial).
• As such, the typically dosing of IVIG for myositis in usual practice is based principally on the legacy of the doses used in the sentinel reports of IVIG for PM by Roifman et al., PMID 2883...