NZ study links surgical ward nurse shortages to higher death rates, modelling suggests 182 lives could be saved each year
A major New Zealand study involving more than 200,000 surgical patients has found lower nurse staffing on hospital wards is associated with significantly higher rates of death and complications after surgery, with researchers estimating that correcting observed staffing shortages could be associated with around 182 fewer deaths every year.
NEW ZEALAND: New research from the University of Auckland has added significant new evidence to the debate over hospital nurse staffing, finding patients recovering from surgery faced poorer outcomes when wards were understaffed.
The national study examined 202,428 adult patients across 223,415 surgical admissions at 24 New Zealand public hospitals between 2022 and 2024.
Researchers linked individual surgical outcomes with staffing information from 94 surgical wards, allowing them to examine how staffing levels during hospital stays were associated with patients' chances of developing complications or dying.
The study was published in the ANZ Journal of Surgery on 13 August 2026.
Its findings were stark.
Of more than 281,000 surgical ward shifts examined, 43.5% were understaffed, while 28.3% met the researchers' definition of a "shift below target".
One fewer nurse linked to 13% higher odds of death
After adjusting for patient, procedure and hospital factors, researchers found that each reduction equivalent to one nurse per shift was associated with:
13% higher odds of death within 90 days
7% higher odds of postoperative complications
7% higher odds of "failure to rescue"
"Failure to rescue" refers to a patient dying after developing a postoperative complication.
The adjusted association with mortality was an odds ratio of 1.13, with a 95% confidence interval of 1.07 to 1.18.
The corresponding adjusted odds ratios were 1.07 for complications and 1.07 for failure to rescue.
More than 6,000 patients died within 90 days
Among the 223,415 eligible surgical admissions studied, 6,296 resulted in death within 90 days of surgery, representing 2.8%.
Postoperative complications occurred in 41,722 admissions, or 18.7%.
Among patients who developed complications, the failure-to-rescue rate was 15.1%.
General surgery accounted for the largest proportion of procedures at 36.3%, followed by orthopaedic surgery at 30.7%.
Almost 48% of procedures were elective.
Modelling suggests 182 fewer deaths each year
Perhaps the study's most significant finding came from researchers modelling what could happen if the observed staffing deficits on surgical wards were corrected.
They calculated an annual staffing shortfall equivalent to 141.3 full-time equivalent positions, or about 166 additional nurses.
Correcting that observed deficit was modelled to require approximately $18.26 million in additional annual staffing expenditure.
Under that scenario, researchers projected 182.2 fewer postoperative deaths each year, with a 95% confidence interval ranging from 97 to 273.8 fewer deaths.
That would represent approximately 8.7% of the country's total postoperative death burden included in the modelling.
The modelling does not mean researchers have demonstrated that hiring exactly 166 nurses would definitively prevent 182 deaths every year.
Rather, it estimates the potential improvement based on the relationship between staffing levels and patient outcomes observed in the national data.
227,570 hours of staffing shortfall
The scale of the staffing deficit identified by researchers was also significant.
Across surgical wards, the study calculated an annual negative staffing variance of approximately 227,570 nursing care hours.
That was equivalent to the 141.3 full-time equivalent shortfall.
The study also found day shifts were more likely to be understaffed than evening or night shifts.
University of Auckland Professor of Surgery and study co-author Ian Bissett said the research was unusual because it connected individual surgical outcomes with staffing information at shift level.
“What’s unique about this research is that it uses New Zealand data linking three years of individual surgical patient outcomes with the nursing staff ratios for each specific shift that the patients were in hospital,” Bissett said in a statement released by the New Zealand Nurses Organisation.
Why nurses matter after an operation
Surgery itself is only one part of a patient's hospital journey.
The hours and days immediately following an operation can be critical because patients may develop bleeding, infections, respiratory problems, blood clots or other complications.
Ward nurses regularly monitor patients, check vital signs, administer treatment and identify deterioration.
When something changes, recognising the problem and escalating it to the appropriate clinical team can be crucial.
The researchers said lower staffing could potentially affect postoperative outcomes through several mechanisms, including reduced surveillance, delayed recognition of deterioration and delays in clinical tasks or escalation.
However, they also cautioned that the observed relationship should be understood as a hospital system-level association rather than a single proven causal pathway.
NZNO calls for wards to be fully staffed
The New Zealand Nurses Organisation says the research reinforces its longstanding concerns about staffing levels.
NZNO Perioperative Nurses College chair Lucy Middleton said nurses are often the people monitoring patients most closely immediately after surgery.
“Nurses are at the bedside when patients come out of surgery. We raise the alarm if our patients’ condition is deteriorating,” Middleton said.
“But to do this well, we need to be fully staffed so we can monitor vital signs and immediately escalate any concerns.”
NZNO is calling on Health New Zealand Te Whatu Ora to staff postoperative wards according to established safe-staffing tools and patient need.
Study also identifies inequalities
Researchers found another concerning pattern.
Among patients who died, Māori, Pacific peoples and patients living in more socio-economically deprived communities were more likely to have been exposed to poorer ward staffing during their admission.
The authors said this highlighted inequalities in how system-level conditions associated with postoperative safety were distributed.
They concluded that nurse staffing was a modifiable health-system factor that should be considered alongside other measures aimed at preventing patient harm and improving surgical outcomes.
Important limitations
The researchers acknowledged several limitations.
The study was observational, meaning it can identify strong associations but cannot prove that nurse shortages alone caused individual deaths or complications.
Staff shortages can themselves reflect several overlapping problems, including sick leave, vacancies, unexpected increases in patient demand, staff redeployment and financial or workforce constraints.
Researchers also did not have the individual ward location of every patient. Staffing exposure therefore represented a weighted measure across surgical wards within each hospital.
The staffing data also included available care hours from nurses and healthcare assistants because detailed information about staff grades and skill mix was unavailable.
Importantly, the researchers noted that a negative staffing variance did not automatically mean care on an individual shift was unsafe, because factors such as staff experience, skill mix and deployment also matter.
One of New Zealand's largest datasets on the issue
Despite those limitations, the scale of the research makes it significant.
Rather than relying simply on surveys or average hospital staffing levels, researchers linked prospectively collected staffing information with national administrative health datasets covering hundreds of thousands of operations.
The research was supported by the Health Research Council of New Zealand, and the authors declared no conflicts of interest.
Their conclusion was clear: lower nurse staffing on surgical wards was independently associated with increased postoperative mortality, complications and failure to rescue.
For a health system facing continuing workforce pressures, the research provides a measurable indication of what inadequate staffing may mean not only for nurses and hospital workloads, but for the patients recovering in those wards.
Source: “Association of Surgical Ward Nurse Staffing With Postoperative Mortality and Failure to Rescue”, ANZ Journal of Surgery, University of Auckland researchers; New Zealand Nurses Organisation. Reporting and additional context by Webfit News.
