How to Define a Frequent Caller to the Prehospital Emergency Medical Services? Literature-Based vs. Data-Driven Approach.

Abstract

Objectives: To provide and test different definitions of a frequent caller to the prehospital emergency medical services, grounded in both literature and empirical data, in order to spark discussion about definitions and how to make studies on frequent callers more comparable.

Methods: A cross-sectional register study of emergency calls made to the Emergency Medical Coordination Center (EMCC) covering the Central Denmark Region in 2022. Three definitions were developed: one as the average number of calls derived from definitions in the previous literature, while the other two were determined using a data-driven approach, representing the top 1% and 0.5% most frequent callers. Unadjusted logistic regression was used to measure odds ratios to examine non-causal associations between predictive factors and frequent callers within each definition.

Results: The analysis included 65,522 emergency calls concerning 49,623 unique individuals. For this specific population, the definitions resulted in the following three thresholds; literature-based definition: ≥43, top 1%: ≥5, and top 0.5%: ≥8 emergency calls per year. There was great variation between the populations of frequent callers captured by the three definitions. Across definitions, frequent callers constituted a relatively small proportion of the total population contacting the EMCC, while they made a significant share of the calls.

Conclusions: We suggest that the 1%-definition is the most suitable for future research on frequent callers to the prehospital EMS as it was able to account for the complexity of this group of citizens and could be applied across prehospital EMS in other contexts and countries. Based on this definition, the most characteristic patterns in emergency calls from frequent callers were low level of urgency, recontact within 24 h, and more calls due to behavioral, psychological, and unclear problems compared to non-frequent callers.