University of Otago Researchers Uncover Ethnicity's Direct Link to Preventable Deaths

A groundbreaking study published in the New Zealand Medical Journal (NZMJ) has demonstrated that ethnicity independently influences health outcomes in New Zealand, even when accounting for factors like deprivation, income, and pre-existing morbidity. Led by researchers from the University of Otago, the analysis reveals stark disparities in amenable mortality—deaths that could be prevented or treated through timely healthcare interventions. This finding challenges recent government policies and underscores the need for ethnicity-aware health strategies to achieve equity, particularly for Māori and Pacific populations.

The study, titled "Is ethnicity an independent predictor of health need? Linked cohort logistic regression analysis to predict amenable mortality," tracked nearly 42 million person-years of data from 2009 to 2018 for individuals under 75 years old. It identified 52,371 amenable deaths, with a crude rate of 124 per 100,000 person-years. After rigorous adjustments, Māori faced 46% higher odds of such deaths (odds ratio [OR] 1.46, 95% CI 1.43–1.50), Pacific peoples 18% higher (OR 1.18, 95% CI 1.14–1.23), and Asians lower odds (OR 0.54, 95% CI 0.52–0.57) compared to Europeans.

Understanding Amenable Mortality: A Key Metric for Health System Performance

Amenable mortality refers to deaths from causes where effective and timely healthcare can intervene to prevent or substantially reduce fatalities. Examples include treatable infections, certain cancers if detected early, cardiovascular events with prompt care, and vaccine-preventable diseases. In New Zealand (Aotearoa), this metric highlights systemic gaps, as rates climb with age (peaking in 55–74 year-olds), male sex, rural residence, high deprivation quintiles, low income, and elevated morbidity scores via the M3 index—a validated measure of multi-morbidity from hospital data.

The M3 index categorizes risk: zero prior conditions yield baseline risk, while scores over 2 signal nearly 7% annual amenable mortality probability. This study's use of Stats NZ's Integrated Data Infrastructure (IDI)—linking census, mortality, hospital discharges, tax, and address data—ensures robust, population-level insights, minimizing biases common in smaller surveys.

Methodology: Isolating Ethnicity's Independent Effect

Researchers employed logistic regression on annual cohorts from 30 June 2009 to 2018, each followed for 12 months. Univariate models first assessed individual predictors, followed by multivariate stepwise inclusion: age, sex, rurality, deprivation (NZDep quintiles), income (past 5-year quintiles, age-stratified), and M3 morbidity. Likelihood ratio tests confirmed ethnicity's additive value (p<0.001).

• Crude Māori OR: 2.46 vs European, attenuating to 1.46 fully adjusted—deprivation and morbidity explain some but not all excess.
• Pacific OR: From crude ~1.8 to 1.18 adjusted.
• Inclusion of ethnicity improved prediction beyond socio-economic or health status alone.

This stepwise approach reveals ethnicity captures unmeasured factors like racism, cultural barriers, or biological differences, vital for Te Tiriti o Waitangi obligations to Māori health equity.

Authors from University of Otago: Pioneering Public Health Equity Research

The study team hails from the University of Otago, New Zealand's premier institution for health sciences. Lead author Andrea Teng is a Senior Research Fellow at the Department of Public Health, Wellington; Melissa McLeod an Associate Professor there; and senior author Professor Sue Crengle from the Division of Health Sciences, Dunedin. Crengle, a Māori health expert, emphasized: "Even after taking into account all other variables, ethnicity still makes a difference to amenable mortality."

Otago's contributions extend prior work on rural Māori mortality inequities and multimorbidity. Aspiring researchers can explore research jobs at NZ universities or career advice for public health roles.

Government Policy Backdrop: 2024 Cabinet Directive Sparks Debate

In 2024, the Aotearoa New Zealand Cabinet directed restricting ethnicity as a 'need' proxy for services, demanding strong evidence, alternatives like deprivation, and evaluations. This study counters: excluding ethnicity underfunds Māori primary care (per Waitangi Tribunal WAI 2575) and ignores 2026 capitation formula revisions omitting it despite multimorbidity inclusion.

Authors argue ethnicity proxies racism's health impacts, unmet needs from earlier disease onset in Māori, and service access barriers. "Failure to include ethnicity... will negatively impact our ability to deliver equal health outcomes," they warn.

Persistent Ethnic Disparities: Māori and Pacific Health Gaps

Life expectancy gaps endure: Māori ~7 years behind Europeans, Pacific ~6 years, despite gains. Māori mortality 1.7x non-Māori in 2022; amenable deaths 3x higher unadjusted. Lung cancer drives much absolute inequality (44-50% Māori excess 2006-11).

Cultural context: Colonization legacies, urban migration disrupt whānau support; Pacific overcrowding exacerbates communicable risks. University-led interventions, like Otago's youth health programs, offer models.

Implications for Healthcare Delivery and Equity

Incorporating ethnicity in funding prioritizes high-need groups, enabling targeted screening (e.g., earlier for Māori CVD/diabetes), culturally safe services, and bias training. Without it, universal approaches perpetuate gaps—e.g., same-age hypertension checks miss Māori's decade-earlier onset.

• Benefits: Reduced amenable deaths, Treaty compliance.
• Challenges: Data accuracy (prioritized ethnicity used), political resistance.
• Solutions: Combine ethnicity + deprivation + M3 in formulas.

For health professionals, this highlights clinical research jobs addressing disparities.

Broader Context: Historical and Recent Trends

Decades of data show Māori all-cause mortality highest, declining slowest pre-COVID. Avoidable deaths: 53% Māori, 47% Pacific (2019 study). 2025 Health NZ reports confirm gaps; smoking, multimorbidity key drivers. University of Otago's longitudinal work informs policy.

Future Directions: Research, Policy, and Actionable Steps

Extend to post-2019 data (COVID impacts); trial ethnicity-adjusted funding. Stakeholders: Health NZ integrate findings; unis expand Māori/Pacific researchers.

Professionals: Advocate equity; students pursue university jobs in epidemiology. Explore Rate My Professor for Otago faculty insights.

Photo by Nappy on Unsplash

Conclusion: Towards Health Equity Through Evidence-Based Reform

This Otago-NZMJ study proves ethnicity's irreplaceable role in predicting health needs. Policymakers must heed it for equitable outcomes. Discover opportunities at higher ed jobs, career advice, or post a job to attract talent tackling these issues.