I'm pretty sure this is generally accepted to be true in the medical/scientific community (and I suspect isn't new, considering how long opium and its derivativ

I'm pretty sure this is generally accepted to be true in the medical/scientific community (and I suspect isn't new, considering how long opium and its derivatives have been in use). Using "opioid long term pain" or "opioid chronic pain" as search terms for Google or Google Scholar should bring up plenty of reviews and meta-studies that elaborate on this concept.