Predictive value of ionized calcium in critically ill patients: an analysis of a large clinical database MIMIC II

Ionized calcium (iCa) has been investigated for its association with mortality in intensive care unit (ICU) patients in many studies. However, these studies are small in sample size and the results are conflicting. The present study aimed to establish the association of iCa with mortality by using a large clinical database. Multiparameter Intelligent Monitoring in Intensive Care II (MIMIC II) database was used for analysis. Patients older than 15 years were eligible, and patients without iCa measured during their ICU stay were excluded. Demographic data and clinical characteristics were extracted and compared between survivors and non-survivors. iCa measure on ICU admission was defined as Ca0; Camax was the maximum iCa during ICU stay; Camin was the minimum value of iCa during the ICU stay; Camean was the arithmetic mean iCa during ICU stay. A total of 15409 ICU admissions satisfied our inclusion criteria and were included in our analysis. The prevalence of hypocalcemia on ICU entry was 62.06%. Ca0 was significantly lower in non-survivors than in survivors (1.11 ± 0.14 vs 1.13 ± 0.10 mmol/l, p