Abstract

Background: Over the past two decades, the proportion of very old intensive care patients (VIPs; aged ≥ 80 years) admitted to intensive care units has significantly increased. Despite advances in critical care, outcomes for this vulnerable population remain variable and poorly understood across different eras in medical practice.

Objectives: This study aimed to compare the one-year outcomes of VIPs admitted to the ICU between 2005–2009 (05–09) and 2015–2019 (15–19), assess shifts in demographics and case mix, and evaluate outcomes for time-sensitive admission diagnoses.

Design and Setting: Single-center retrospective cohort study conducted in a 12-bed mixed medical-surgical ICU at Sint-Blasius General Hospital, Belgium.

Methods: All ICU admissions of VIPs during the two periods were analyzed. Patients with missing data or non-retrievable patient files were excluded. For patients with repeated ICU admissions within one year, only data from the last admission were considered. Propensity Score Matching (PSM) was applied to adjust for age, sex, SAPS II score, and APACHE IV admission diagnosis. ICU Length of Stay (LOS) was additionally explored as an indirect surrogate for end-of-life decision-making. Kaplan-Meier survival analysis and statistical tests were used to compare outcomes up to 1 year after ICU admission.

Results: A total of 885 VIPs were admitted between 05–09 versus 1267 between 15–19. After exclusion, 747 and 1066 ICU admissions from the 05–09 and 15–19 periods, respectively, were analyzed. ICU admissions of VIPs increased among the 15–19 group, with older patients exhibiting lower SAPS II scores. Over time, the top 25 APACHE IV diagnoses showed significant changes. Medical admissions were predominant, whereas planned surgical admissions decreased in 15–19. Despite these shifts, the overall mortality rate remained unchanged. However, there was a notable improvement in ICU LOS in 15–19. PSM was employed to adjust for biases and create two well-balanced cohorts of 506 patients, revealing no significant differences in overall mortality. For time-sensitive conditions, such as AMI, CVA, and sepsis, ICU mortality and LOS improved significantly in 15–19, whereas outcomes for less time-sensitive conditions, such as CHF, COPD exacerbation, and pneumonia, remained unchanged. The reduction in ICU LOS in the later period was primarily driven by shorter ICU stays among survivors (PSM analysis), as suggested by an exploratory surrogate analysis.

Conclusion: Despite an older and more complex ICU population in 15–19, adjusted survival outcomes remained stable. Improvements in early recognition and standardized treatment protocols have likely contributed to better outcomes for specific acute conditions. However, missing frailty data and residual confounding limit the ability to draw definitive conclusions. Further prospective studies are warranted.