I can see why people are confused. My DH has just retired, and has been sent a DWP leaflet entitled Notes about State Pension, presumably the one that ethel's friend has. It does state that when you are in receipt of a state pension (no other benefits or allowances are mentioned), there are all sorts of changes of circumstances that you must inform the DWP about. One is going into hospital.
I think that this is just a very badly written leaflet. Apparently he must inform the DWP if his spouse (me) goes into hospital, leaves the UK for more than 3 months, stops living with him, gets any benefit, pension or entitlement, is involved in a trade dispute, starts or stops work, has a change in earnings etc, etc. As his pension is his alone, containing no allowance for me at all, it surely wouldn't be affected by any of these events? I can't see why he should be contacting them every time I blow my nose! 