I don't know about the validity of your claim. Cancer was a death sentence. Many folks with heart attacks didn't make it. Many of today's manageable conditions didn't have such happy results, and people died. When you were hospitalized, there wasn't much that could be done, either diagnostics or treatments. Many of the the pharmaceuticals we have now didn't exist. Life expectancy was a decade shorter. Medicare and Medicaid didn't even exist until the mid 60's. I'm not sure Kennedy's time was this nirvana you think it was, particularly for the poor.
Here's an interesting article I found about that:
https://www.ssa.gov/history/pdf/Heal...Early1960s.pdf