I work for the NHS at the moment and we do as Benchmark does and our sickness levels are dropping. Our sickness level dropped by 1.2% this month. It doesn't sound much, but when you've got 8,500 staff it adds up.
We have a policy that says if they have three or more absences (no matter how long) in a six month period then they're asked to come in for an informal sickness review. They're asked if we can help in any way, e.g. hours of work, counselling, etc. We also monitor people's sickness to see if there is a pattern to their sickness, i.e. always on a monday, always on a bank holiday, etc.
It goes into much more depth than this, but that's the general idea. It goes onto formal review, first formal warning, bla bla bla, but i'd be here all day typing.
Ali