Wisdom of the caregivers: pooling individual subjective reports to diagnose states of consciousness in brain-injured patients, a monocentric prospective study

Abstract

Objectives: The clinical distinction between vegetative state/unresponsive wakefulness syndrome (UWS) and minimally conscious state (MCS) is a key step to elaborate a prognosis and formulate an appropriate medical plan for any patient suffering from disorders of consciousness (DoC). However, this assessment is often challenging and may require specialised expertise. In this study, we hypothesised that pooling subjective reports of the level of consciousness of a given patient across several nursing staff members can be used to clinically detect MCS.

Setting and participants: Patients referred to consciousness assessment were prospectively screened. MCS (target condition) was defined according to the best Coma Recovery Scale-Revised score (CRS-R) obtained from expert physicians (reference standard). 'DoC-feeling' score was defined as the median of individual subjective reports pooled from multiple staff members during a week of hospitalisation (index test). Individual ratings were collected at the end of each shift using a 100 mm Visual Analogue Scale, blinded from the reference standard. Diagnostic accuracy was evaluated using area under the receiver operating characteristic curve (AUC), sensitivity and specificity metrics.

Results: 692 ratings performed by 83 nursing staff members were collected from 47 patients. Twenty patients were diagnosed with UWS and 27 with MCS. DoC-feeling scores obtained by pooling all individual ratings obtained for a given patient were significantly greater in patients with MCS than with UWS (59.2 mm (IQR: 27.3-77.3) vs 7.2 mm (IQR: 2.4-11.4); p<0.001) yielding an AUC of 0.92 (95% CI 0.84 to 0.99).

Conclusions: DoC-feeling capitalises on the expertise of nursing staff to evaluate patients' consciousness. Together with the CRS-R as well as with brain imaging, DoC-feeling might improve diagnostic and prognostic accuracy of patients with DoC.

Keywords: clinical assessment; coma recovery scale - revised; diagnosis; disorders of consciousness; group decision making; minimally conscious state.

Figure 1

Disorders of consciousness (DoC)-feeling score. Each patient was evaluated around three times by DoC experts using the Coma Recovery Scale-Revised (CRS-R). In parallel, nursing staff members reported their daily observations using the DoC-feeling Visual Analogue Scale. The reference standard was defined as the best state of consciousness observed during one of the CRS-R and the patient was coded as being in an unresponsive wakefulness syndrome (UWS) or a minimally conscious state (MCS) accordingly (reference standard). All individual DoC-feeling scores obtained during the whole hospital stay were pooled and the median value (represented by the vertical dashed line) of the polled results was defined as the DoC-feeling score (index test).

Figure 2

Flow chart. Flow chart representing the repartition of patients while using a disorder of consciousness (DoC)-feeling score (index test) cut-off value of 16.7 mm. Exit-MCS: Patient able to communicate reliably or to use objects functionally. CRS-R, Coma Recovery Scale-Revised; MCS, minimally conscious state; UWS, unresponsive wakefulness syndrome.

Figure 3

Individual disorders of consciousness (DoC)-feeling ratings. DoC-feeling ratings tended to be smaller in patients with unresponsive wakefulness syndrome (UWS) when compared with patients with minimally conscious state (MCS). All individual ratings are shown (dots, n=692), alongside boxplots helping to visualise the median and the IQR for both UWS (on the left in red) and MCS (on the right in blue) patients.

Figure 4

DoC-feeling scores. DoC-feeling scores were obtained by pooling individual ratings obtained for each patient. DoC-feeling scores were smaller for patients with UWS than for MCS (A, B) and also correlated with the CRS-R score (A). Area under the ROC curve (C), sensitivity (Se) and specificity (Sp) for several cut-offs (D) revealed very good performances at identifying the MCS. ***P<0.001. CRS-R, Coma Recovery Scale-Revised; DoC, disorders of consciousness; MCS, minimally conscious state; ROC, receiver operating characteristic; UWS, unresponsive wakefulness syndrome.