District health board figures show hospitals are not on track to complete the same amount of elective surgeries as they did last year, the National Party says.
The National Party collated discharge figures for elective surgery patients to March - nine months into the financial year - which show levels are at 70 percent, but should be at 75 percent.
National leader Simon Bridges said it was the lowest rate of completed elective surgeries in a decade and by the end of June there would have been 10,000 fewer than last year.
"This isn't low-level stuff. It's cancer, cardiac, things like prostate cancer which can be incredibly uncomfortable, incredibly stressful and there's risk of infection and the like if they're not dealt with in good time."
Mr Bridges said that figure was made up of a 6500 shortfall from the same time last year, another 1500 delayed in April due to the strikes and an extrapolation of data which estimated there would be around 1900 less completed in the final quarter.
"We've seen less new money going into the system to keep up. I think it also has to be true that when the health targets around elective surgeries and other things were cancelled.
"It means there's no measurement and no ability to hold DHBs accountable and drive performance."
Acute surgeries were more or less static this time last year.
Health Minister David Clark said some operations carried out under the elective surgery branch last year were now being completed under a different system, so may not be reflected in the data.
"We've set the expectation that more procedures like Avastin injections and skin lesion removals are performed in more appropriate settings like outpatients and in primary care rather than in surgical environments.
"I'm advised there are also data collection delays ... It's simply too early to say where we'll end up with these numbers."
Mr Bridges said he would be "vigourously pursuing" Mr Clark on this topic, in the coming weeks.