[Temporal trends in characteristics, resource occupation and outcomes of critically ill patients: a single-center study (2014-2021)]

To analyze temporal trends of disease characteristics, resource occupation and prognosis of critically ill patients from 2014 to 2021, so as to provide a basis for further optimizing the allocation of medical resources.

A retrospective analysis was conducted on clinical data from adult patients admitted to the intensive care unit (ICU) of Xuanwu Hospital of Capital Medical University from January 1, 2014 to December 31, 2021. The temporal trends of demographic data, comorbidities, reasons for admission, whether surgery was performed on the day of admission to the ICU, acute physiology and chronic health evaluation II (APACHE II) within 24 hours of admission to the ICU, whether mechanical ventilation, renal replacement therapy, and their duration of treatment were received during ICU stay, as well as whether vasoactive drugs were received and their types, the length of ICU stay and hospitalization time, and ICU mortality and in-hospital mortality were analyzed.

A total of 31 535 patients were ultimately included in the study with complete clinical data. From 2014 to 2021, 3 541, 3 529, 3 583, 3 637, 3 772, 5 241, 3 688, and 4 544 adult ICU patients were enrolled annually. The median age of all patients was 61 (51, 72) years, with 58.9% male, and the median APACHE II score was 9 (6, 14). From 2014 to 2021, the median age of patients admitted to the ICU decreased from 62 (52, 75) years to 61 (49, 70) years, and the patients aged ≥ 70 years decreased by about 10% (gradually decreasing from 35.5% to 25.4%, P < 0.05). The proportion of patients with APACHE II ≥ 15 increased from 19.8% to 30.4% (P < 0.05), the patients < 70 years with APACHE II ≥ 15 increased from 8.2% in 2014 to 20.5% in 2021 (P < 0.05). The proportion of patients transferred to the ICU after elective surgery and emergency surgery increased by about 7% and 10%, respectively (from 42.3% to 49.3%, from 14.5% to 24.4%, both P < 0.05). The proportion of patients receiving mechanical ventilation showed no significant temporal trend, but the proportion of patients receiving invasive mechanical ventilation for more than 48 hours increased (42.3% to 44.9%, P < 0.05). Patients with invasive mechanical ventilation for more than 48 hours had a median duration of mechanical ventilation of 238 (123, 419) hours and a median hospitalization time of 20 (13, 31) days, both of which were significantly larger than those overall [26 (8, 202) hours, 12 (8, 18) days, respectively]. ICU mortality of all patients decreased from 5.6% to 3.3% (P < 0.05), and in-hospital mortality decreased from 6.9% to 3.9% (P < 0.05), and the ICU mortality and in-hospital mortality of patients aged ≥ 70 years decreased by 2.1% and 2.9%, respectively (from 3.8% to 1.7%, and from 4.6% to 1.7%, respectively, both P < 0.05).

During the study period, while the proportion of elderly patients admitted to the ICU decreased, the severity of their illness and the proportion of surgical patients increased, with the most significant increase observed in the severity of illness among patients under the age of 70. The ICU mortality and in-hospital mortality showed a downward trend, with the largest decrease observed in patients ≥ 70 years old. The mechanical ventilation time and hospitalization time of patients with invasive mechanical ventilation for more than 48 hours were significantly prolonged.