Redesigning 9-1-1 Paramedic Pathways: Evaluation of the IMPACC Model of Care

Paramedic services remain organized around rapid response, time-sensitive events, and hospital conveyance despite increasing 9-1-1 use for lower-acuity and undifferentiated presentations. There is a need to improve the alignment of paramedic services for patients seeking non-emergency care via the 9-1-1 system. A redesigned model of care to improve patient care in the community (IMPACC) was embedded within an existing 9-1-1 system to expand paramedic clinical care and decision architecture. This study evaluated whether IMPACC improved alignment between patient need and care pathway selection.

We conducted a retrospective observational cohort study as an implementation evaluation of an embedded 9-1-1 model of care using encounters attended by IMPACC-trained paramedics from April 2024 to February 2026. Encounters were classified by IMPACC activation status and compared within the same operational environment. Analyses examined patient characteristics, clinical selectivity, disposition, care intensity, operational time, 72-hour repeat contact, paramedic-level heterogeneity, and temporal trends. A secondary exact-matched analysis compared IMPACC activations with standard-practice controls.

Of 7,382 encounters, IMPACC was activated in 9.9%, increasing to 12.6% among CTAS 3-5 encounters and 28.3% among the top quartile of paramedics. Activation was concentrated among clinically ambiguous complaints. Overall, IMPACC-activated encounters had lower hospital transport rates than non-activated encounters (36.4% vs. 81.7%) and greater clinical engagement. In the exact-matched analysis, IMPACC activations remained less likely to result in transport than standard-practice controls (42.9% vs. 79.2%). Median total time on task was longer under IMPACC in both the within-cohort comparison (90.0 vs. 66.5 minutes) and matched comparison (92.0 vs. 62.0 minutes) but narrowed over time. Repeat 72-hour contact was 4.0%. Paramedic-level heterogeneity persisted after case-mix adjustment (ICC 0.33; MOR 3.39), and activation declined over time (OR per month 0.94).

This study demonstrates that an embedded redesign of 9-1-1 paramedic care can expand pathway options at the point of emergency access and redistribute care from default hospital conveyance toward structured on-scene assessment, consultation, discharge, and referral pathways with an increase investment of time on task. Sustained impact will require implementation support and governance, cross-sector integration, and alignment-focused performance metrics.