There are a lot of threads on interventions. Just do a search and you'll find them all. Results, and opinions, regarding interventions vary widely here, as do the definitions around what constitutes "working."
I did one on my wife because I thought I was qualified to plan an intervention because I'm not an alcoholic (and didn't think anything was wrong with me-- just her). The hubris of that version of me was mind boggling.
Through one filter it was a disaster, though I was able to force her into a recovery center by threatening to divorce her. Through another filter it was the first step towards her finding recovery several years later using some of the tools she learned there, and for me finding Alanon (thank God). I'd do it again, but I'd do it again with the assistance and guidance of a professional interventionist (money be damned).
My two cents. Your results may vary.
Cyranoak
P.s. She also learned, in recovery, new ways to hide her drinking and the proper things to say to doctors and loved ones so it sounds like they are getting better. Already an excellent liar and manipulator, she got even better.