The impact of post-operative sepsis on mortality after hospital discharge among elective surgical patients: a population-based cohort study

Lixin Ou, Jack Chen, Ken Hillman, Arthas Flabouris, Michael Parr, Hassan Assareh, Rinaldo Bellomo

Our aim in the present study was to assess the mortality impact of hospital-acquired post-operative sepsis up to 1 year after hospital discharge among adult non-short-stay elective surgical patients. We conducted a population-based, retrospective cohort study of all elective surgical patients admitted to 82 public acute hospitals between 1 January 2007 and 31 December 2012 in New South Wales, Australia. All adult elective surgical admission patients who stayed in hospital for ≥4 days and survived to discharge after post-operative sepsis were identified using the Admitted Patient Data Collection records linked with the Registry of Births, Deaths, and Marriages. We assessed post-discharge mortality rates at 30 days, 60 days, 90 days and 1 year and compared them with those of patients without post-operative sepsis. We studied 144,503 survivors to discharge. Of these, 1857 (1.3%) had experienced post-operative sepsis. Their post-discharge mortality rates at 30 days, 60 days, 90 days and 1 year were 4.6%, 6.7%, 8.1% and 13.5% (vs 0.7%, 1.2%, 1.5% and 3.8% in the non-sepsis cohort), respectively (P < 0.0001 for all). After adjustment for patient and hospital characteristics, post-operative sepsis remained independently associated with a higher mortality risk (30-day mortality HR 2.75, 95% CI 2.14-3.53; 60-day mortality HR 2.45, 95% CI 1.94-3.10; 90-day mortality HR 2.31, 95% CI 1.85-2.87; 1-year mortality HR 1.71, 95% CI 1.46-2.00). Being older than 75 years of age (HR 3.50, 95% CI 1.56-7.87) and presence of severe/very severe co-morbidities as defined by Charlson co-morbidity index (severe vs normal HR 2.05, 95% CI 1.45-2.89; very severe vs normal HR 2.17, 95% CI 1.49-3.17) were the only other significant independent predictors of increased 1-year mortality. Among elective surgical patients, post-operative sepsis is independently associated with increased post-discharge mortality up to 1 year after hospital discharge. This risk is particularly high in the first month, in older age patients and in the presence of severe/very severe co-morbidities. This high-risk population can be targeted for interventions.