Temporal trends in sepsis hospitalisations and mortality in Aotearoa New Zealand, 2000-2019: a population-based study

Globally, sepsis remains a substantial public health concern. To inform policy development and interventions for sepsis prevention, treatment, and surveillance in Aotearoa New Zealand (Aotearoa), we describe population-level epidemiological trends in hospitalised sepsis and mortality over two decades by major sociodemographic characteristics.

We undertook a retrospective, population-based descriptive study of all sepsis-associated hospitalisation (SAH) in Aotearoa between 2000 and 2019 using previously published case identification strategies and International Classification of Diseases, Tenth Revision (ICD-10) codes to identify SAHs in the National Minimum Dataset. Incidence and mortality rates, and case fatality risks were calculated along with analyses of trends over the 20-year observation period. Rate estimates were standardised to the age structure of the total population identified in the 2018 New Zealand Census.

We identified 266,105 unique SAH cases and 27,402 associated deaths, with an average age-standardised incidence rate (ASIR) of 320.4 admissions per 100,000 population and an age-standardised mortality rate (ASMR) of 34.2 deaths per 100,000 population. An average annual ASIR increase of 4.5% was observed, from 217.3 admissions in 2000 to 386.9 admissions per 100,000 population in 2019. ASMR decreased annually from 37.1 deaths in 2000 to 31.3 deaths per 100,000 population in 2019. Case fatality risk decreased from 15.9 deaths in 2000 to 8.1 deaths per 100 admissions in 2019, primarily driven by improvements in patient survival in ≥40-year age groups. Significant SAH incidence and mortality disparities were observed between patient populations, particularly by age, ethnicity and socioeconomic deprivation. Māori and Pacific Peoples had SAH incidence rates that were 1.7 and 2.3 times, respectively, higher than those of NMPA ethnicity, and had mortality rates that were 1.6 and 1.7 times higher. Similarly, those living in areas of high socioeconomic deprivation were twice as likely to develop SAH, and their SAH mortality rate was twice as high as that of those living in areas of the least socioeconomic deprivation.

Sepsis is common in Aotearoa and makes a substantial contribution to population mortality. Significant variation in incidence and mortality rate estimates was observed between patient populations, with higher rates in those <1 year and ≥70 years, of Māori or Pacific ethnicity, and those living in areas of high socioeconomic deprivation. Our findings highlight the burden of SAH and the need for targeted interventions to address sepsis prevention, surveillance and support for sepsis survivors in Aotearoa.

Health Research Council of New Zealand.