Mapping Glasgow Coma scale to AVPU scores among adults in the prehospital setting

To develop a translation between the Glasgow Come Scale and the Alert-Verbal-Pain-Unresponsive (AVPU) scale among adults with out-of-hospital emergencies.

We performed a retrospective analysis of adults (≥18 years) from the 2022 National Emergency Medical Services (EMS) Information System with a ground scene encounter with a concurrently documented GCS and AVPU assessment. Using a training partition of 2.5 million encounters, we performed a grid search to identify all combinations of mutually exclusive cutpoints which divided the GCS into four segments. We identified the combination with the highest Kappa statistic and reported metrics of performance in this sample in the test partition.

We identified 16,321,299 encounters with a concurrent AVPU and GCS. Using the AVPU scale, 93.3 % were classified as Alert; 2.9 % as Verbal; 1.5 % as Pain; and 2.3 % as Unresponsive. Using a grid-based search, optimal cutpoints were identified when using a GCS of 14-15 for Alert, 10-13 for Verbal, 7-9 for Pain, and 3-6 for Unresponsive. Cohen's Kappa was 0.63 in the test partition, indicating substantial agreement. Intraclass F1 score varied across different alertness levels and were 0.97 for "Alert", 0.43 for "Verbal", 0.49 for "Pain", and 0.83 for "Unresponsive". Findings were similar in analyses performed by age group and by the presence or absence of trauma.

We report an optimal crosswalk between the AVPU and GCS scales. Performance in the Verbal and Pain categories was lower than the Alert and Unresponsive categories. These findings may facilitate clinician handovers between EMS and non-EMS clinicians.