Prognostic Value of the Intensive Care Respiratory Distress Observation Scale on ICU Admission

BACKGROUND: The association between dyspnea and mortality has not been demonstrated in the ICU setting. We tested the hypothesis that dyspnea (self-reported respiratory discomfort) or its observational correlates (5-item intensive care Respiratory Distress Observation Scale [IC-RDOS]) assessed on ICU admission would be associated with ICU mortality.

METHODS: Ancillary analysis of single-center data prospectively collected from 220 communicative ICU subjects allocated to a derivation cohort of 120 subjects and a separate validation cohort of 100 subjects. Dyspnea was assessed dichotomously (yes/no), with a dyspnea visual analog scale (measured in mm), and IC-RDOS was calculated. Multivariate logistic regression was used to identify factors associated with ICU and hospital mortality.

RESULTS: Dyspnea was reported by 69 (58%; median 45 [interquartile range [IQR] 32–60] mm) and 47 (47%; 38 [IQR 26–48] mm) subjects in the derivation and validation cohorts, respectively. IC-RDOS was 2.3 (1.2–3.1) and 2.4 (1.3–2.8), respectively. IC-RDOS values were higher in subjects with dyspnea than in subjects without dyspnea in both the derivation cohort (2.6 [2.2–4.6] vs 1.4 [0.9–2.4], P < .001) and the validation cohort (2.6 [2.3–4.4] vs 2.2 [1.0–2.8], P < .001). On multivariate analysis of the derivation cohort, admission for hemorrhagic shock (odds ratio 13.98), IC-RDOS (odds ratio 1.77), and Simplified Acute Physiology Score II (odds ratio 1.10) was associated with ICU mortality. Areas under the receiving operating characteristic curve of IC-RDOS to predict ICU mortality were 0.785 and 0.794 in the derivation and validation cohorts, respectively.

CONCLUSIONS: IC-RDOS, an observational correlate of dyspnea, but not dyspnea itself, was associated with higher mortality in ICU subjects.