There are a few ‘variables’ you’ve not cited….

1-dosages as in ‘adequate’ dosages were not mentioned. As many here know, some docs are very scroogelike when starting one out on IVIG.
2-Dosage amounts and of the correct brands as well are mitigating factors in whether one IG product might work better than another… I’ve not looked up the reference but I do recall that about 7 years ago, there were more brands available and several incuded more of some IG sub-immune particles that many could not tolerate.
Most important in all this? IS that most docs, hospitals or infusion services never report adverse reactions! It is up to the patients.
Most simply give up as they fear it’s too hard to report the reactions [I HAVE reported, and it’s EASY!] or they fear a ‘retribution’ by either the docs or the providers. I feel it’s essential for safety purposes.
Usually most patients ‘don’t respond’ because the doses they are initially given are simply not adequate loading doses or maintenance doses. Since I’ve started on IVIG that ‘response’ rate # hasn’t really changed at all? At about 30-35%…but why not? Has never been adequately researched nor explained. Unfortunately the available alternatives are very few and far between, all with possible minor and MAJOR consequences for the long term.
I will say, that my initial first doses? I responded to very well! And, unfortunately my doses have had to increase as my immune system has built up a greater ‘rebellion’.
As for getting any right dosage? Read the ‘full prescribing information’ then? Do the math! Not enuf? Ask why not the rite amount? At times a doc’s being stingy at key times is an invitation to prolong the whole issue, which if given in a timely and proactive manner? Could slow or stop things in their tracks!
Unfortunately, most of us get to the IVIG too late to reverse all damages, but they can be restored. I was partially restored [so to speak] until 2 years ago when an accident resulting in other issues sent me backwards big-time. I keep hoping and have faith that I can ‘get back’ more than I have now!
I hope you too will try and have hope and faith as well.