Mortality Trends Across Key Diagnostic Groups in Australian and New Zealand ICUs Over the Past 30 Years.

Abstract

Objectives: The Australia and New Zealand Intensive Care Society (ANZICS) Adult Patient Database (APD) has been operational for 3 decades. It is important to understand how mortality outcomes have changed across diagnostic groups over time to facilitate the planning of future healthcare resources. We evaluated the trends in risk-adjusted mortality for ICU patients over the last 30 years.

Design: A retrospective cohort study.

Setting: All ICUs in Australia and New Zealand that contributed data to the ANZICS APD from January 1993 to December 2022.

Patients: Adult patients (≥ 16 yr) admitted to Australian and New Zealand ICUs.

Interventions: None.

Measurements and main results: The final cohort included 2,838,654 patients from 209 ICUs. Compared with the first decade patients admitted during the final decade of the study were older (60.0 yr [18.2 yr] vs. 62.0 yr [17.8 yr]), more often had a least one major comorbidity (23.2% vs. 25.2%), and had higher Acute Physiology and Chronic Health Evaluation III scores (45.6 [28.1] vs. 50.9 [24.1]). The five diagnostic groups with the highest mortality rates were cardiac arrest (53.6%), stroke and intracranial hemorrhage (34.8%), subarachnoid hemorrhage (21.2%), pneumonia (19.2%), and sepsis (19%). Risk-adjusted mortality decreased until 2010 but then plateaued. Cardiac arrest saw the greatest improvement in risk-adjusted mortality between the third vs. first study decades (odds ratio [OR], 0.82 [0.81-0.83]), while pneumonia saw the least (OR, 0.87 [0.87-0.88]). The pattern of improvement for most diagnostic groups were similar; however, mortality from stroke and intracranial hemorrhage continued to improve, whereas mortality from cardiac arrest appears to have increased over the past 10 years.

Conclusions: There have been substantial improvements in risk-adjusted mortality among ICU patients over the past 30 years; however, this improvement has plateaued recently. The reasons for this plateau warrant further investigation.