Does anyone know what studies have been done to determine how long a lapband can last? I have been banded for almost 4 years and have been relatively complication free(knock on wood) and was just wondering how long I can expect it to last?

I don't have the answer although I bet there's research on it but I have a friend who's had hers 4 years and still going strong. Her mother was banded in the 90s and still has hers... so I'd guess quite a long time? I guess I figured forever myself.

Suppose to be forever according to my doctor

Theoretically a lifetime but in practice some parts may need replacing before then. It is possible that the "balloon" part may become less effective from constantly be stretched, a bit like a balloon that has been blown up a couple of times. If that happens then not a major problem they can replace it or if a newer better surgery is available at that point you may choose to revise to that. Most prosthetics whether they be knees,hips or heart valves do seem to eventually need to be replaced.