These records at National Archives can sort out a few research problems. They were important enough to index onto card files for casual people turning up at Auckland archives expecting some quick results. I think they are especially important for those family members who are 'background people' who don't figure much in other records. Hospitals recorded varying amounts of information. This probably had to do with funding, which hospital board was going to pay up for whom, but that's just a personal theory.
I haven't got an example of Thames Hospital records which I should have got to show you, because they are quite comprehensive, however, I have a list of some of the patients on my Coromandel site.
Coromandel Hospital record sample.