Validation of case correctness and time intervals agreement in the Swedish registry of cardiopulmonary resuscitation using emergency medical dispatch data, 2015-2024

ObjectiveTo validate case number correctness and time interval agreement in the Swedish Registry of Cardiopulmonary Resuscitation (SRCR) for out-of-hospital cardiac arrest (OHCA) by linkage to Emergency Medical Dispatch Centre (EMDC) data between 2015 and 2024. MethodsIn this retrospective validation study, OHCA records reported to the SCRC were linked with EMDC-indexed OHCA for validation and correction of EMS case numbers. We quantified the proportion of correct EMS case numbers reported as agreement for fully correct and partially correct EMS case numbers in SRCR. Time interval agreement was assessed by comparing dispatch to arrival (unit response time) and call start to arrival (total response time) between SRCR and EMDC. For each linked case, time differences were calculated as (SRCR - EMDC) in seconds. Median differences were estimated using Bayesian quantile regression. ResultsEMS case number completeness was high, but the proportion of fully correct case numbers was limited. Among 56,969 SRCR records, 1,004 (1.8%) lacked an EMS case number. The proportion of SRCR records with partially correct EMS case numbers was around 90% up to the year 2020 and declined to 85% in 2022-2024. Dispatch-related time intervals showed high agreement between sources, with a median difference of -0.3 seconds (95% CrI -3.9 to 4.0). In contrast, SRCR total response time (from dispatch call answer to arrival at scene) was shorter than EMDC, with a median difference of 80.9 seconds (95% CrI -84.7 to -77.0). ConclusionSRCR unit response time reflects EMDC operational recording. The SRCR total response times were consistently shorter than the interval at the EMDC, indicating a potential underestimation of the total EMS response time in the registry.