Life expectancy rise in rich countries slows down: took 30 years to prove

I wonder how much impact there will be on average life expectancy uncovering that a lot of the super-long-lived population examples have been pension fraud.

Probably not much because you can find long-lived populations that don't follow the administrative boundaries of pensions.

King County in Washington State, which contains the Seattle metro area, has a life expectancy of 86.3 years. This is higher than any country in the world. If you move one county south (Pierce), it is 75.7 years, slightly worse than the US average currently. Not surprisingly, there are many obvious factors that may contribute to this e.g. the obesity rate in Pierce County is 50% higher and the obesity rate in King County is roughly half the US obesity rate. The Seattle metro is a relatively walkable city and people do, Pierce County is not. As a matter of demographics, King County is significantly more Asian than Pierce County. And so on.

Both counties are geographically large and contain many municipalities. It is difficult to come up with a theory where pension fraud in King County is so high relative to Pierce County that it explains a >10 year difference in life expectancy.