Mekanik Ventilatörde Izlenen Hastalarda Farklı Mortalite Skorlarının Karşılaştırılması

Abstract

Mortality scoring systems are widely used in pediatric intensive care units. The most well-known scores are PRISM and PIM scores. These systems are used to identify the patient at risk, determine treatment plan early and ensure quality control of units. In addition, they provide an objective assesment while determining patients in clinical trials and comparing groups with each other. A good scoring system should be reliable and applicable in different patient groups and units. Application of mechanical ventilatory support and treatment are frequent in the pediatric intensive care units. Ventilation parameters are not included in PRISM III score while taking part in PIM2 score. The aim of this study is applying standardized mortality scores in mechanically ventilated patients and determining whether they are appropriate to predict the risk of mortality. For this purpose, PRISM III-24 and PIM2 scores were calculated in mechanically ventilated 150 patients between April 2011 to April 2013. The area under the ROC curve was 0.66 and p-value calculated by goodness-of-fit test was 0.002 for PRISM III-24 score. The discrimination and calibration of score were assesed as poor. Standardized mortality ratio (SMR) was 0.85 at cut-off point (72.5) determined by 51.2 % sensitivity and 75.2 % specificity; SMR was 0.69 at cut-off point (58.65) determined by 61 % sensitivity and 68.9 % specificity. SMR values shows that observed mortality was less than expected mortality. Also according to determined cut-off points, 20 (48.8 %) and 16 (39 %) of patients who died didn’t take place in expected mortality respectively. PRISM III-24 score missed a significant portion of patients in observed mortality. The area under the ROC curve was 0.52, p-value calculated by goodness-of-fit test was 0.68 for PIM2 score. A standart ROC curve couldn’t be obtained for PIM2 score. True positive and false positive points intersects greatly on the curve. SMR could not be evaluated since there was no ideal cut-off point. Although the observed mortality was 27.3 %, the expected mortality was 100 % in 92 % of patients according to PIM2 score. The score was unable to discriminate survivors and non-survivors, the observed and expected mortality was not compatible. It was aimed to find more specific parameters to develop an appropriate scoring system for ventilated patients. For this purpose oxygenation index (OI) was calculated at 0, 12, 24, 72 hours of ventilation to asses oxygenation. OI-12 and OI-72 were found to be higher in non-survivors than survivors. In addition, high mortality rate in patients who need HFO was associated to higher value of OI-72. As a result, the PRISM III-24 and PIM2 scores were failed to predict mortality risk in ventilated patients. Standard scoring systems should be reconsidered in this respect. Especially the severity of respiratory failure should be evaluated properly to determine mortality risk for ventilated patients. OI can be used to predict degree of respiratory failure and mortality risk. Therefore, future studies can be done with larger groups of ventilated patients to asses whether OI estimates mortality risk independently. Thus OI may be included in standart mortality and organ failure scoring systems and validity can be evaluated.