Development and inter-rater reliability of a simple prehospital mobility score for use in emergency patients

Background: Mobility assessment enhances the ability of vital sign-based early warning scores to predict risk. Currently mobility is not routinely assessed in a standardized manner in Denmark during the ambulance transfer of unselected emergency patients. The aim of this study was to develop and test the inter-rater reliability of a simple prehospital mobility score for pre-hospital use in ambulances and to test its inter-rater reliability.

Method: Following a pilot study, we developed a 4-level prehospital mobility score based of the question"How much help did the patient need to be mobilized to the ambulance trolley". Possible scores were no-, a little-, moderate-, and a lot of help. A cross-sectional study of inter-rater agreement among ambulance personnel was then carried out. Paramedics on ambulance runs in the North- and Central Denmark Region, as well as The Fareoe Islands, were included as a convenience sample between July 2020-May 2021. The simple prehospital mobility score was tested, both by the paramedics in the ambulance and by an additional observer. The study outcomes were inter-rater agreements by weighted kappa between the paramedics and between observers and paramedics.

Results: We included 251 mobility assessments where the patient mobility was scored. Paramedics agreed on the mobility score for 202 patients (80,5%). For 47 (18.7%), there was a deviation of one between scores, in two (< 1%) there was a deviation of two and none had a deviation of three (Table 1). Inter-rater agreement between paramedics in all three regions showed a kappa-coefficient of 0.84 (CI 95%: 0.79;0.88). Between observers and paramedics in North Denmark Region and Faroe Islands the kappa-coefficient was 0.82 (CI 95%: 0.77;0.86).

Conclusion: We developed a simple prehospital mobility score, which was feasible in a prehospital setting and with a high inter-rater agreement between paramedics and observers.