Epidemiology and outcomes of septic shock in Japan: a nationwide retrospective cohort study from a medical claims database by the Japan Sepsis Alliance (JaSA) study group.

backgroundSeptic shock is a critical condition associated with high mortality and resource utilization. Although improvements in early recognition and management of sepsis have been reported globally, the trends in clinical outcomes among patients with septic shock in Japan remain unclear.

methodsWe conducted a retrospective cohort study using data from the Japanese Diagnosis Procedure Combination (DPC) nationwide medical claims database from 2010 to 2020. Adult inpatients (aged ≥ 18 years) with sepsis were identified based on the criteria for presumed serious infection (blood culture plus ≥ 4 days of intravenous antibiotics) and acute organ dysfunction, determined using the International Classification of Diseases, 10th Revision codes and treatment procedures. This approach is broadly consistent with the Sepsis-3 definition but adapted for administrative data. Septic shock was defined as the administration of at least one vasopressor, without requiring hypotension or lactate criteria, in line with previous administrative database studies. The primary outcome was in-hospital mortality rate. Secondary outcomes included deaths per 1,000 inpatients, hospital length of stay (LOS), intensive care unit (ICU) admission rates, and ICU LOS. Outcomes among patients with non-shock sepsis were also analyzed for comparison. Trends and subgroup analyses were performed according to age and sex and combinations of ICU admission and shock status.

resultsAmong 4,426,342 patients with sepsis, 649,082 (14.7%) had septic shock. In-hospital mortality was significantly higher in the shock group than in the non-shock group (36.5% vs. 20.0%, P < 0.001), with a longer median LOS (38 vs. 25 days) and higher ICU admission (50.7% vs. 19.2%). From 2010 to 2020, in-hospital mortality decreased from 46.7 to 33.2% in the shock group and from 26.0 to 18.0% in the non-shock group. The number of deaths per 1,000 inpatients only slightly decreased in the shock group (2.8 to 2.4) but increased in the non-shock group (7.0 to 8.2). The proportion of patients with septic shock increased from 0.64 to 0.83%. Meanwhile, the mean LOS decreased from 61.0 to 53.6 days in the shock group and from 45.7 to 34.4 days in the non-shock group. Only about half of the patients with septic shock were admitted to ICUs, and mortality was higher in non-ICU patients throughout most of the study period, although the difference diminished in 2019. Subgroup analyses showed persistently high mortality rates among older patients (≥ 85 years) and males across the study period.

conclusionsDespite improvements in survival and LOS over the past decade, septic shock remains a highly lethal and resource-intensive condition in Japan, with in-hospital mortality rates exceeding 30%. Mortality was particularly high among older patients, with rates consistently exceeding 40% among those aged ≥ 85 years.