Zhang Zhongheng, Xu Xiao, Ni Hongying, Deng Hongsheng
Department of Critical Care Medicine, Jinhua Municipal Central Hospital, Jinhua Hospital of Zhejiang University, Zhejiang, P.R. China.
PLoS One. 2014 Apr 15;9(4):e95204. doi: 10.1371/journal.pone.0095204. eCollection 2014.
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<0.001). In multivariate analysis, moderate hypocalcemia in Ca0 was significantly associated with increased risk of death (OR: 1.943; 95% CI: 1.340-2.817), and mild hypercalcemia was associated with lower mortality (OR: 0.553, 95% CI: 0.400-0.767). While moderate and mild hypocalcemia in Camean is associated with increased risk of death (OR: 1.153, 95% CI: 1.006-1.322 and OR: 2.520, 95% CI: 1.485-4.278), hypercalcemia in Camean is not significantly associated with ICU mortality.
The relationship between Ca0 and clinical outcome follows an "U" shaped curve with the nadir at the normal range, extending slightly to hypercalcemia. Mild hypercalcemia in Ca0 is protective, whereas moderate and mild hypocalcemia in Camean is associated with increased risk of death.
许多研究对重症监护病房（ICU）患者的离子钙（iCa）与死亡率之间的关联进行了调查。然而，这些研究样本量较小且结果相互矛盾。本研究旨在通过使用大型临床数据库来确定iCa与死亡率之间的关联。
使用重症监护多参数智能监测II（MIMIC II）数据库进行分析。纳入年龄大于15岁的患者，排除在ICU住院期间未测量iCa的患者。提取幸存者和非幸存者的人口统计学数据及临床特征并进行比较。将ICU入院时的iCa测量值定义为Ca0；Camax为ICU住院期间的最高iCa值；Camin为ICU住院期间iCa的最小值；Camean为ICU住院期间iCa的算术平均值。
共有15409例ICU入院患者符合纳入标准并纳入分析。ICU入院时低钙血症的患病率为62.06%。非幸存者的Ca0显著低于幸存者（1.11±0.14 vs 1.13±0.10 mmol/l，p<0.001）。在多变量分析中，Ca0中的中度低钙血症与死亡风险增加显著相关（OR：1.943；95%CI：1.340 - 2.817），轻度高钙血症与较低死亡率相关（OR：0.553，95%CI：0.400 - 0.767）。虽然Camean中的中度和轻度低钙血症与死亡风险增加相关（OR：1.153，95%CI：1.006 - 1.322和OR：2.520，95%CI：1.485 - 4.278），但Camean中的高钙血症与ICU死亡率无显著关联。
Ca0与临床结局之间的关系呈“U”形曲线，最低点在正常范围内，略延伸至高钙血症。Ca0中的轻度高钙血症具有保护作用，而Camean中的中度和轻度低钙血症与死亡风险增加相关。
