A heart procedure performed on the wrong patient is one of a growing list of errors New Zealand hospitals are making in treating patients.
The Health Quality and Safety Commission says there has been a 21% increase in the number of serious injuries, mistakes and near-misses at district health boards.
The commission says 437 "serious adverse events" were recorded at DHBs between July 2012 and June this year - 77 more than in its previous report.
The heart procedure performed at Waikato Hospital was an angiogram; other mistakes included the incorrect prescription of drugs and delays in providing treatment.
The commission says many of the incidents involved people being injured from falls while in hospital. However, it says the increased number of events stems not so much from more accidents happening than from more people reporting them when they do.
New Zealand Nurses Organisation spokesperson Kate Weston says while higher reporting levels play a part, a lack of funds for staffing is also a factor.
She said a 94.6% increase in falls in the past four years suggests that there is a wider problem.
"It's a very direct link that's getting stated in international literature around what we call nurse sensitive indicators like falls, medication that are being missed, delayed monitoring of vital signs - all point really strongly commonly to insufficient nurse numbers."
For the first time, the commission included non-DHB health providers in its survey. Its report highlights 52 serious events reported by non-DHB health providers such as ambulance services, rest homes and private hospitals.