Research was carried out recently by Southern District Health Board staff to try to find ways to improve productivity at Dunedin and Southland Hospitals.
"Surgical caseweights [the level of complexity of a procedure] pre-Covid were trending upwards," the report said.
"However, they took a large hit with Covid and have not recovered and also look to be trending downwards post-Covid."
SDHB chairman Pete Hodgson said the research was interesting, and that it was frustrating the board had received the information so soon before it was disbanded, meaning it could not ask for more details or act upon it.
"There are some significant and fascinating insights but, as always, they raise more questions than answers," he said.
Mr Hodgson said the numbers suggested Southland Hospital was performing better than Dunedin Hospital, but SDHB chief operating officer Hamish Brown said he believed that reflected the nature of the procedures performed at each hospital, as more complex cases were usually transferred away from smaller hospitals.
Board member Lyndell Kelly said there had been a 6.2% increase in patient throughput since 2014-15 and a 5.6% increase in elective surgery, which should be applauded.
"This is for a hospital which has the same number of beds, if not fewer, and increased frailty of the population, and also a staff cohort that wants a decent lifestyle rather than to sacrifice itself for its patients, so I think this is a decent result and we shoudn’t be fretting about it."
Mr Brown said the research had identified some long-term trends, and also highlighted some issues which had been exacerbated by Covid-19.
"As the acute caseweights have gone up we have seen a reduction in elective caseweights, so therefore there is a finite amount of capacity in the system," he said.
"And as the acutes go up we have to manage it the only way that we can, which is to put less electives through, and that is a challenge I think."
Hospitals now operated at about 90% occupancy, well up from the research starting date.
"Traditionally availability of theatre suites has been a point of constraint but earlier this year it swung around to availability of beds being a constraint.
"Now we are starting to get more beds open and it has swung around to availability of theatres being an issue, and some of that is to do with the physical size of theatres — day surgery procedures which would normally happen in a day surgery suite, such as ophthalmology, now need to occur in a main operating theatre."
Much modern medical equipment cannot fit in the current day surgery suites: in the new Dunedin hospital those rooms are planned to be twice the size.
