ObjectiveTo evaluate the predictive value of critical illness scores for hospital mortality of severe respiratory diseases in respiratory intensive care unit (ICU).MethodsThe clinical data of the patients who needed intensive care and primary diagnosed with respiratory diseases from June, 2001 to Octomber, 2012 were extracted from MIMIC-Ⅲ database. The Acute Physiology Score (APS) Ⅲ, Simplified Acute Physiology Score (SAPS) Ⅱ, Oxford Acute Severity of Illness Score (OASIS), Logistic Organ Dysfunction System (LODS), Systemic Inflammatory Response Syndrome (SIRS) and Sequential Organ Failure Assessment (SOFA) were calculated according to the requirements of each scoring system. ICU mortality was set up as primary outcome and receiver operating characteristic (ROC) analysis was performed to evaluate the predictive performances by comparing the areas under ROC curve (AUC). According to whether they received invasive mechanical ventilation during ICU, the patients were divided into two groups (group A: without invasive mechanical ventilation group; group B: with invasive mechanical ventilation group). The AUCs of six scoring systems were calculated for groups A and B, and the ROC curves were compared independently.ResultsA total of 2988 patients were recruited, male accounted for 49.4%, median age was 67 (55, 79), and ICU mortality was 13.2%. The AUCs of SAPSⅡ, LODS, APSⅢ, OASIS, SOFA and SIRS were 0.73 (0.70, 0.75), 0.71 (0.68, 0.73), 0.69 (0.67, 0.72), 0.69 (0.67, 0.72), 0.67 (0.64, 0.70) and 0.58 (0.56, 0.62). Subgroup analysis showed that in group A, the AUCs of OASIS, SAPSⅡ, LODS, APSⅢ, SOFA and SIRS were 0.81 (0.76, 0.85), 0.80 (0.75, 0.85), 0.77 (0.72, 0.83), 0.75 (0.70, 0.80), 0.73 (0.68, 0.78) and 0.63 (0.56, 0.69) in the prediction of ICU mortality; in group B, the AUCs of SAPSⅡ, APSⅢ, LODS, SOFA, OASIS and SIRS were 0.68 (0.64, 0.71), 0.67 (0.63, 0.70), 0.65 (0.62, 0.69), 0.62 (0.59, 0.66), 0.62 (0.58, 0.65) and 0.57 (0.54, 0.61) in the prediction of ICU mortality. The results of independent ROC curve showed that the AUC differences between groups A and B were statistically significant in terms of OASIS, SAPSⅡ, LODS, APSⅢ and SOFA, but there were no significant differences in SIRS.ConclusionsThe predictive values of six critical illness scores for ICU mortality in respiratory intensive care are low. Lack of ability to predict ICU mortality of patients with invasive mechanical ventilation should hold primary responsibility.