Epidemiology and age-related mortality in critically ill patients with intra-abdominal infection or sepsis: an international cohort study

•Older age reduces the odds of survival in intensive care unit patients with intra-abdominal infection/sepsis.•In octogenarians with diffuse peritonitis and sepsis/septic shock, mortality may increase up to 70%.•Underlying conditions such as diabetes, chronic heart failure, liver disease and malnutrition further burden the prognosis.•As these risk factors for death are non-modifiable, it is unclear how to improve survival in older adults with intra-abdominal infection/sepsis.•These data stress the importance of timely patient- and family-centred care conferences discussing realistic goals of care. To describe epidemiology and age-related mortality in critically ill older adults with intra-abdominal infection. A secondary analysis was undertaken of a prospective, multi-national, observational study (Abdominal Sepsis Study, ClinicalTrials.gov #NCT03270345) including patients with intra-abdominal infection from 309 intensive care units (ICUs) in 42 countries between January and December 2016. Mortality was considered as ICU mortality, with a minimum of 28 days of observation when patients were discharged earlier. Relationships with mortality were assessed by logistic regression analysis. The cohort included 2337 patients. Four age groups were defined: middle-aged patients [reference category; 40–59 years; n=659 (28.2%)], young-old patients [60–69 years; n=622 (26.6%)], middle-old patients [70–79 years; n=667 (28.5%)] and very old patients [≥80 years; n=389 (16.6%)]. Secondary peritonitis was the predominant infection (68.7%) and was equally prevalent across age groups. Mortality increased with age: 20.9% in middle-aged patients, 30.5% in young-old patients, 31.2% in middle-old patients, and 44.7% in very old patients (P60 years was associated with mortality; patients aged ≥80 years had the worst prognosis. Comorbidities and overall disease severity further compromised survival. As all of these factors are non-modif