Sepsis incidence and mortality are underestimated in Australian intensive care unit administrative data

TO THE EDITOR: We congratulate Heldens and colleagues1 for their work investigating the prevalence and mortality of sepsis within a tertiary hospital intensive care unit (ICU). As the authors rightly point out in their article and podcast, this requires careful screening, consistent diagnostic criteria, and considerable time and effort.

The Australian and New Zealand Intensive Care Society (ANZICS) registry provides a highly specific, widely applicable, cost‐effective, timely and practical epidemiological measure of the prevalence and outcomes of sepsis and septic shock as a primary cause of ICU admissions throughout Australia and New Zealand.2 Findings from the registry appear consistent with those of Heldens and colleagues.1 However, their article confirms that there are more patients with sepsis within our ICUs than those who enter with this as an admission diagnosis.

Between January 2016 and June 2018, 11.6% (43 529/374 442) of the ICU admissions reported to the ANZICS Adult Patient Database were due to sepsis as defined by the international Sepsis‐3 taskforce.3 In tertiary hospital ICUs, this was slightly higher at 12.1% (19 204/159 067), which is between 14.0% (121/864) by clinical criteria and 11.3% (98/864) by database criteria found within the first 24 hours of ICU admission by Heldens et al. With the recent addition of information about vasopressors and lactate levels, ANZICS can also now confidently identify patients with septic shock. Of 59 069 ICU admissions with available information, 3.3% (1978) had septic shock, again similar to the findings of Heldens et al. ICU admissions in the ANZICS registry due to sepsis or septic shock were associated with mortality of 15.1% and 26.7%, respectively. Heldens et al reported a similar mortality of 24% (8/33) with septic shock identified in the first 24 hours of admission (Appendix, table 4).

The study by Heldens et al and the findings from the ANZICS registry are complementary. Together they highlight how the measurement of sepsis depends on the exact definition applied, and the population under consideration, which may vary between clinical practice, prospective observational and interventional studies, and widespread epidemiological comparisons.