Hawke's Bay District Health Board renal recall clinics have identified a data error that affected 301 patients due for appointments.
Robin Whyman, chief medical and dental officer, said the issue involved patients who had their first specialist assessment in clinic and were due for a "recall" (follow-up) appointment.
The error dated back to March 2019.
"These recalls are booked within varying timeframes, depending on the patient's condition ie within 2-4 weeks, 3-6 months, or up to 1 year out," Whyman said.
"The DHB has launched an investigation to determine why patient recall files were not being flagged correctly for follow-up. While that process is ongoing, the extent of the error has been dated back to March 2019."
As of Monday, the DHB had contacted 218 patients and new appointments were made in clinic, 127 patients had been seen and an additional 50 will have been seen by the end of this week.
"High risk patients were prioritised and seen first," Whyman said.
About 83 patients were currently being contacted with appointments scheduled for January/February.
"Patients are being personally phoned to advise of the error, apologise and arrange an appointment as soon as possible."
The DHB has advised GPs, asking them to contact the service if they are aware of, or have clinical concern about any patients waiting longer than expected to be seen in our recall clinics.
"While awaiting follow-up appointments with the renal clinic, patients are routinely seen by their GP if they have concerns about their health.
"Clinicians are manually checking other patient lists of lower risk. These reviews may identify additional patients requiring follow-up."
The issue has been classified as an "adverse event" by the DHB.
"Hawke's Bay DHB apologises to these patients for this error."
Health Minister David Clark was advised of the renal patient recall error at HBDHB under the "no surprises" policy which states, "In their relationship with Ministers, officials should be guided by the 'no surprises' principle."
Clark said it was "not appropriate" for to speculate on the error while the investigation was taking place.
"This will be a distressing situation for those patients involved. My expectation is the DHB will continue to communicate with them and ensure they receive the healthcare they need.
"It's important the DHB establishes what happened and acts to prevent this error from happening again."