Increasing perioperative age and comorbidity: a 16-year cohort study at two University hospital sites in Sweden

Background: Increasing life expectancy affects all aspects of healthcare. During surgery, elderly patients are prone to complications and have a higher risk of death. The authors aimed to investigate if adult patients undergoing surgery at a large Swedish university hospital were getting older and sicker over time and if this potential shift in age and illness severity was associated with higher patient mortality rates. Materials and methods: This was a 16-year cohort study on all surgical procedures performed in adult patients 2006-2021 at two sites of Karolinska University Hospital. Study data was obtained from the surgical system, electronic medical records, and cause-of-death register. Information on age, sex, American Society of Anesthesiologists (ASA) classification, date, type, acuity and duration of surgery was collected. ICD codes were used to calculate the Charlson comorbidity index (CCI). Short-term, medium-term and long-term mortality rates were assessed. Logistic regression models were used to evaluate changes over time. Results: There were 622 814 surgical procedures 2006-2021. Age, ASA classification, and CCI increased over time (P<0.0001). The proportions of age older than or equal to 60 years increased from 41.8 to 52.8% and of ASA class greater than or equal to 3 from 22.5 to 47.6%. Comparing 2018-2021 with 2006-2009, odds ratios (95% CIs) of 30-day, 90-day and 365-day mortality, adjusted for age, sex, non-elective surgery and ASA classification, decreased significantly to 0.75 (0.71-0.79), 0.72 (0.69-0.76), and 0.76 (0.74-0.79), respectively. Conclusion: Although the surgical population got older and sicker during the 16-year study period, short-term, medium-term and long-term mortality rates decreased significantly. These demographic shifts must be taken into account when planning for future healthcare needs to preserve patient safety.