Probabilistic Linkage of Prehospital and Outcomes Data in Out-of-hospital Cardiac Arrest

Abstract

Objective Lack of longitudinal patient outcome data is an important barrier in emergency medical services (EMS) research. We aimed to demonstrate the feasibility of linking prehospital data from the California EMS Information Systems (CEMSIS) database to outcomes data from the California Office of Statewide Health Planning and Development (OSHPD) database for patients with out-of-hospital cardiac arrest (OHCA). Methods We included patients age 18 years or older who sustained non-traumatic OHCA and were included in the 2010–2011 CEMSIS databases. The CEMSIS database is a unified EMS data collection system for California. The OSHPD database is a comprehensive data collection system for patient-level inpatient and emergency department encounters in California. OHCA patients were identified in the CEMSIS database using cardiac rhythm, procedures, medications, and provider impression. Probabilistic linkage blocks were created using in hospital death or one of the following primary or secondary diagnoses (I CD-9-CM) in the OSHPD databases: cardiac arrest (427.5), sudden death (798), ventricular tachycardia (427.1), ventricular fibrillation (427.4), and acute myocardial infarction (410.xx). Blocking variables included incident date, gender, date of birth, age, and/or destination facility. Due to the volume of cases, match thresholds were established based on clerical record review for each block individually. Match variables included incident date, destination facility, date of birth, sex, race, and ethnicity. Results Of the 14,603 cases of OHCA we identified in the prehospital databases, 91 (0.6%) duplicate records were excluded. Overall, 46% of the data used in the linkage algorithm were missing in CEMSIS. We linked 4,961/14,512 (34.2%) records. Linkage rates varied significantly by local EMS agency, ranging from 1.4% to 61.1% (OR for linkage 0.009–0.76; p<0.0001). After excluding the local EMS agency with the outlying low linkage rate, we linked 4,934/12,596 (39.2%) records. Conclusion Probabilistic linkage of CEMSIS prehospital data with OSHPD outcomes data was severely limited by the completeness of the EMS data. States and EMS agencies should aim to overcome data limitations so that more effective linkages are possible.

Billing diagnoses do not accurately identify out-of-hospital cardiac arrest patients: An analysis of a regional healthcare system

“…Linkage of existing prehospital OHCA with hospital administrative data is a potential tool but presents unique challenges with limited linkage capability. 21 Prospectively maintained ED-based or EMS-based registries are probably the best methods for compete identification of OHCA subjects. 22 …”

Regional Variation in the Incidence and Outcomes of In-Hospital Cardiac Arrest in the United States

“…Indeed, previous studies have used ICD-9-CM code 427.5 listed as the principal diagnosis to identify OHCA cases. 15,16 Similarly, cardiac arrest may also be coded in patients with do-not-resuscitate (DNR) orders for whom no treatment is attempted. Furthermore, health data coders may not include code 427.5, preferring to rank other diagnoses codes higher (eg, comorbidities), which will skew the coded incidence of IHCA.…”

Regional Variation in Outcomes of Hospitalized Patients Having Out-of-Hospital Cardiac Arrest

“…These codes have been used in prior studies to identify patients with out-of-hospital cardiac arrest. 6, 7 Prior studies of state-wide databases as well as Medicare/Medicaid claims data have shown ICD-9-CM codes, using principal diagnosis, to be reliable in accurately identifying patients with OHCA. 8–10 All patients with concomitant diagnosis of injury were excluded.…”