Landmark Intensive Care Study Shows Significant Disparities In Health Outcomes For Māori Patients

The first large-scale national study to compare health outcomes for Māori and European patients admitted to New Zealand intensive care units (ICU) has been published today in the New Zealand Medical Journal.

The Medical Research Institute of New Zealand (MRINZ) compared and analysed data from more than 50,000 patients admitted to all major hospital ICUs over a 10-year period, finding that Māori patients were more likely than European patients to die within 180 days of ICU admission.

The study, Outcomes for Māori and European patients admitted to New Zealand intensive care units between 2009 and 2018, was led by the MRINZ, on behalf of the Australian and New Zealand Intensive Care Society (ANZIC) CORE Management Committee, a leading advocate in critical care.

The study found that Māori are 13 years younger on average when admitted to ICU than European patients. Despite this, Māori patients have more chronic underlying conditions when they are admitted to ICU, including diabetes and kidney disease, and are, on average, more severely unwell and have a higher risk of dying.

Professor Paul Young, MRINZ Deputy Director, Intensive Care Specialist, and study senior author says, “Importantly, when we accounted for underlying conditions and how unwell patients were on hospital arrival, there was no difference in survival rates between Māori and European patients. This implies that differences in health outcomes are unlikely to be related to the care being delivered after patients get to the ICU.”

The observation that Māori ICU patients are much younger than European ICU patients and still have more underlying diseases or medical conditions than their European counterparts implies that an unequal burden of chronic conditions is a major contributor to inequality in ICU outcomes. Another potential factor is that barriers to accessing prompt care for Māori might potentially contribute to higher illness severity by the time of ICU admission.

“Health inequalities are an ongoing major public health concern and a strong focus for the Medical Research Institute of New Zealand." says Professor Young. "Māori are likely to be ill far more frequently, suffer disproportionately high levels of disease, and die younger than non-Māori of the same socioeconomic status. There are also differences in broader societal issues that significantly affect health, including housing, education, employment, and socioeconomic deprivation.”

Dr James Moore, MRINZ Clinical Research Fellow and Intensive Care Specialist, says. “Given Māori are much more likely than European patients to be admitted to the ICU with life-threatening infections, after major trauma, and following a cardiac arrest, these study findings are hugely important in identifying priorities for future research that has the potential to lead to change in clinical practice, and support equitable Māori health outcomes.”

KEY POINTS AT A GLANCE

1. The first large-scale national study to compare outcomes for Māori and European patients admitted to New Zealand intensive care units (ICU) shows that Māori patients were more likely than European patients to die within 180 days of ICU admission.

2. Māori are 13 years younger on average when admitted to ICU than European patients. Despite this, Māori patients have more chronic conditions when they are admitted to ICU (including diabetes and kidney disease), and are, on average, more severely unwell and have a higher chance of dying.

3. When underlying conditions and severity of illness were accounted for, there was no difference in survival rates between Māori and European patients. This implies that differences in health outcomes are unlikely to be related to the care being delivered after patients arrive at an ICU.

4. Outcomes for Māori and European patients admitted to New Zealand intensive care units between 2009 and 2018 was authored by Dr Alice Reid, Professor Michael Bailey, Professor Matire Harwood, Dr James Moore, and Professor Paul Young, on behalf of the ANZICS CORE Management Committee.

5. Given Māori are more likely than European patients to be admitted to the ICU with life-threatening infections, after major trauma, and following a cardiac arrest, continuing to investigate these conditions in Māori patients should be a priority and focus for ongoing critical care research in Aotearoa.

6. The Medical Research Institute of New Zealand (MRINZ) is committed to improving the collection, monitoring, analysis, and reporting of quality ethnicity data, actively supporting more equitable health outcomes for Māori and Pasifika patients in Aotearoa New Zealand.

BACKGROUND TRIAL DETAIL 

This cohort study describes characteristics and outcomes of Māori and European patients admitted to New Zealand intensive care units (ICUs) between June 2009 and 2018.

New Zealand Ministry of Health National Minimum Dataset matched to the Australia New Zealand Intensive Care Society Centre for Outcome and Resource Evaluation Adult Patient Database. The primary outcome was day-180 mortality. Secondary outcomes were ICU mortality, hospital mortality, discharge to home, ICU length of stay, hospital length of stay and survival time. We report associations between Māori ethnicity and each outcome, with European as the reference category, using regression analyses to adjust sequentially for site, deprivation status, gender, year of admission, the Charlson comorbidity index, age, admission source and type, ICU admission diagnosis, ventilation status and illness severity based on physiological parameters.

A total of 52,552 patients from 17 ICUs were included in this study.

Māori admitted to ICU were on average 13 years younger than European patients. A total of 968 of 9,681 (10%) Māori and 2,732 of 42,871 (5.2%) European were admitted after trauma, and 740 of 9,681 (7.6%) and 2,318 of 42,871 (4.4%) were admitted with sepsis, respectively. A total of 1,550 of 9,681 (16.0%) Māori and 6,407 of 42,871 (14.9%) European patients died within 180 days of ICU admission; odds ratio (OR) 1.08; 95% CI, 1.02 to 1.15. When adjusted for age, the OR for day-180 mortality for Māori versus European patients increased substantially. The OR decreased after adjustment for admission source and type, and after accounting for Māori having a higher comorbidity index and more severe illness than European patients. In the final model, incorporating adjustment for all specified variables, Māori ethnicity was not associated with day-180 mortality (adjusted OR 1.01; 95%CI, 0.92 to 1.10). Findings were similar for all secondary outcomes.

Compared to European patients, Māori were markedly more likely to be admitted to the ICU after trauma or with sepsis. Despite Māori being on average 13 years younger at ICU admission than their European counterparts, they had more co-morbidities, higher illness severity and a higher risk of dying within 180 days (about 6 months).

Medical Research Institute of New Zealand 
Rangahautia Te Ora

The Medical Research Institute of New Zealand (MRINZ) is Aotearoa New Zealand’s leading independent medical research institute. MRINZ research is guided by a simple philosophy: it must challenge dogma, increase knowledge, and have the potential to improve clinical practice and outcomes, both in Aotearoa New Zealand, and internationally.

The MRINZ’s research teams are dedicated to investigating important public health problems, delivering high quality evidence on which to improve the management of disease and patient care. An internationally recognised academic institution, the MRINZ operates under a charitable trust pursuing advances in clinical practice and providing a base for specialist training in medical research. The MRINZ is committed to contributing toward a more equitable society that celebrates Te Ao Māori and upholds Te Tiriti o Waitangi.

Professor Paul Young, MRINZ Deputy Director 
Deputy Director, MRINZ; Co-clinical leader and Intensive Care Specialist, Wellington Hospital Intensive Care Unit; Medical Director, Wakefield Hospital Intensive Care Unit, Wakefield Hospital, BSc (Hons), MBChB, PhD, Grad Cert Crit Care Echo, Clinical Associate Professor, University of Melbourne, Adjunct Professor, Monash University. 

Professor Young is a member of the Australian and New Zealand Intensive Care Society Clinical Trials Group (ANZICS CTG) and leading member of the New Zealand ICU research community. His primary interest is in the design and conduct of large-scale multicentre randomised controlled trials in the field of Intensive Care Medicine. He has published over 150 peer-reviewed journal articles including numerous high impact publications in the New England Journal of Medicine, the Lancet, and the Journal of the American Medical Association. He is involved in research collaborations with scientists from Australia, the UK, Canada, the USA, Italy, Scandinavia, Saudi Arabia, and Brazil. He is the Associate Editor for Critical Care and Resuscitation. 

Dr James Moore, MRINZ Clinical Research Fellow

Rangitāne, Te Whānau-a-Apanui, Ngāti Kahungunu

StJ MB ChB FANZCA FCICM — Medical Advisor 

James is an Consultant Anaesthetist & Intensive Care Physician based in Wellington with specialist interests in trauma, cardiothoracic anaesthesia & intensive care, and pre-hospital medicine. He is currently the head of Trauma Services at Wellington Hospital, Clinical Leader for the Central Regional Trauma Network and is a Clinical Senior Lecturer at the University of Otago's Wellington School of Medicine. A graduate of the University of Otago Medical School, James completed his specialist medical training in Aotearoa New Zealand with further subspecialty training in cardiac anaesthesia & intensive care at Royal Papworth Hospital, Cambridge, United Kingdom.

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