Simple prediction of mortality in case of readmission to the intensive care unit

Introduction

Mortality of patients readmitted to the ICU is significantly higher than the mortality of patients treated once in the ICU. A simple method to predict mortality of patients readmitted to the ICU could help to select the most seriously ill readmitted patients.

Methods

Adult patients that were admitted to all three ICUs of the same hospital twice or more times during the same stay in the hospital during a 3-year period were retrospectively selected. The sex and age of surviving and nonsurviving readmitted patients were compared. The mortality rate of patients readmitted into the ICU during 24 and 48 hours was compared with the mortality rate of all readmitted ICU patients. The mortality of patients that were readmitted more than once into the ICU was compared with the mortality of patients that were readmitted once. The duration of stay in other departments before readmission into the ICU of survivors was compared with duration of stay in other departments of nonsurvivors.

Results

A total of 13,343 patients were admitted. Eight hundred and fifty-six patients were readmitted, 172 readmitted patients died in the hospital (hospital mortality – 20.09%). The readmission rate of men was higher in comparison with women (550 vs 306 patients). The mortality of readmitted men was lower than the mortality of readmitted woman; 77 men (17.2%) died vs 95 (25.1%) women (P = 0.00001). The age of 565 patients was lower than 70 years. The mortality of readmitted patients with age lower than 70 years was lower than the mortality of patients older than 70 years; 103 (18.2%) patients younger than 70 years died vs 70 (24%) patients older than 70 years (P = 0.00001). Mortality of patients that were readmitted during 24 or 48 hours was bigger than the mortality of all readmitted patients (26.9% and 25.11% vs 20.09%; P = 0.045 and P = 0.097). The mortality of patients that were readmitted more than once (from a total 160 patients, 41 died – 25.6%) was bigger than the mortality of patients readmitted just once (from a total 696 patients, 131 died – 18.96%) (P = 0.12). The length of stay of nonsurviving readmitted patients in other departments before readmission was higher than the length of stay of survivors (mean 7.64 days vs mean 5.71 days).

Conclusion

Sex and age older than 70 years of patients readmitted to the ICU, readmission during 24 hours, and length of stay in other departments before readmission could be used for simple prediction of mortality of patients readmitted into the ICU. The amount of single patient readmissions to the ICU cannot be used as a predictor of death of patients readmitted to the ICU.