Medicine in 1945 to the mid 1985's depended on blood transfusions to get patients through serious operations for accidents, cancer, blood disease's, open heart surgery etc.
There's virtually no way to tell how many JW's died in those years and continue to die . While medicine has improved there is often no other way to pull someone through serious operations and treatments.
Since there is no real reason to believe that god doesn't want us to get a blood transfusion I have always felt that it was very risky behavior demanded by the WTBTS. That a blood card was a suicide note you carried around with you at all times.
That minors are not in a position to resist the mind control that goes on in the JW world.
My best guess would be that the JW's lose at least as many people needlessly as Jonestown did accept they lose them each and every year since 1945. I can't prove it and it might be a much higher number but that would be, say 1000 people a year for the last 69 years...... Thats what I call a reckless and dangerous belief.