Long-term survival after intensive care: A retrospective cohort study

Background Limited data exist on long-term survival of patients requiring admission to intensive care units (ICUs). The aim of this study was to investigate long-term survival of ICU patients in Iceland and assess changes over a 15-year period. Methods Data were collected on age, gender, admission cause, length of stay, comorbidities, mechanical ventilation and survival of patients 18 years and older admitted to the ICUs in Landspitali during 2002-2016. Long-term survival of patients surviving more than 30 days from admission was estimated and its predictors assessed with Cox regression analysis. Long-term survival was compared to the survival of an age- and gender-matched reference group from the general population. Results Of 15 832 ICU admissions, 55% was medical, 38% was surgical and 7% was due to trauma. The 5-year survival of medical, surgical and trauma patients was 66%, 76% and 92% respectively. Significant survival differences were found between admission subgroups. Higher age and comorbidity burden was related to decreased survival in all patient groups. After correcting for age, gender, comorbidities, length of ICU stay and mechanical ventilation, patient survival improved during the study period only for patients admitted for infections. There was a high variability in the estimated time point where the ICU admission had no residual effect on survival. Conclusions Long-term survival of ICU patients is substantially decreased compared to the general population, but varies based on admission causes. Improved long-term survival of patients admitted with infections could be explained by earlier detection and improved treatment of septic shock.