Age distribution and clinical results of critically ill patients above 65-year-old in an aging society: A retrospective cohort study.

Background:Increasing age has been observed among patients admitted to the intensive care unit(ICU). Age traditionally considered a risk factor for ICU mortality. We investigated how the epidemiology and clinical outcomes of older ICU patients have changed over a decade. Methods:We analyzed patients admitted to the ICU at a university hospital in Seoul, South Korea. We defined patients aged 65 and older as older patients. Changes in age groups and mortality risk factors over the study period were analyzed. Results:A total of 32,322 patients were enrolled who aged ≥ 65 years admitted to the ICUs between January 1, 2007, and December 31, 2017. Patients aged 65 years accounted for 35% and of these, the older(O: 65-74 yrs) comprised 19,630(66.5%), very older(VO: 75-84 yrs) group 8,573(29.1%), and very very older(VVO: 85 years) group 1,300(4.4 %). The mean age of ICU patients over the study period increased(71.9±5.6yrs in 2007 vs. 73.2±6.1yrs in 2017) and the proportions of the VO and VVO group both increased. Over the period, the proportion of female increased(37.9% in 2007 vs. 43.3% in 2017), and increased ICU admissions for medical reasons(39.7% in 2007 vs. 40.2% in 2017). In-hospital mortality declined across all older age groups, from 10.3% in 2007 to 7.6% in 2017. Hospital length of stay(LOS) decreased in all groups, but ICU LOS decreased only in the O and VO groups. Conclusion:The study indicates a changing demographic in ICUs with an increase in older patients, and suggests a need for customized ICU treatment strategies and resources.