Severity scoring systems and different biochemical markers as predictors of mortality in the respiratory ICU

Background
Predicting mortality and outcome of critically ill patients is an interesting point for research, so different acuity scores, such as Acute Physiology and Chronic Health Evaluation II, Simplified Acute Physiology Score II (SAPS II), Mortality Probability Model II (MPM II), and Sequential Organ Failure Assessment (SOFA), and biochemical markers are under investigation for its assessment.


Aim
The aim of this study were to compare between different ICU scores, for predicting mortality and to assess validity of some biochemical markers such as C-reactive protein (CRP), neutrophil–lymphocytic ratio (NLR), platelet to lymphocyte ratio, red cell distribution width, and mean platelet volume in the assessment of ICU outcome.


Patients and methods
This prospective cross-sectional study included 104 patients. The patients were subdivided into survivor and nonsurvivor groups. Acute Physiology and Chronic Health Evaluation II and SAPS II scores of the patients were recorded on the first day of admission to respiratory ICU, while SOFA and MPM II scores were recorded on the first and third (SOFA72, MPM72) days of ICU admission, where both groups were compared in terms of different ICU acuity scores as well as some biochemical markers. Sensitivity and specificity of each parameter for predicting mortality were calculated.


Results
The nonsurvivor group included 41 (39.4%) patients. All model scores as well as CRP and NLR were significantly higher in the nonsurvivor group; SOFA72 score had the highest sensitivity of 94.8% with an area under the roc curve (AUR) of 0.94 while the MPM72 score had the highest specificity of 91% with an AUR of 0.81 with a cutoff value of 5 and16, respectively.


Conclusion
While SOFA72 score has the highest sensitivity, MPM72 score has the highest specificity for predicting ICU mortality. NLR and CRP values are independent prognostic factor for hospital mortality in critically ill patient.