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

Abstract

Background International Classification of Diseases 9th Edition’s Clinical Modification (ICD-9CM) codes are frequently used in health services research. We tested the operating characteristics of ICD-9CM codes for identifying out-of-hospital cardiac arrest (OHCA) subjects. Methods We used ICD-9CM codes to generate an “administrative cohort” of subjects treated after possible OHCA at one of six emergency departments (EDs) between January 2010 and April 2014. We performed a structured chart review to determine proportion of this administrative cohort with actual OHCA (true positive rate for the ICD-9CM-based search method). The largest study site maintains a prospective registry of consecutive OHCA subjects, which we used to construct a “registry cohort”. We used this cohort to calculate the sensitivity of the ICD-9CM-based search strategy at this site, and compared in-hospital mortality and discharge dispositions between the two cohorts using Chi-square tests. Results ICD-9CM codes identified 2461 subjects that comprised the administrative cohort. Of these, the true positive rate for actual OHCA on chart review was 40%. ICD9-CM code sensitivity was 100% for subjects coded as dead on arrival and 19% for subjects coded as surviving to ED disposition. There were 609 OHCA subjects in the registry cohort and 268 subjects in the administrative cohort who presented to registry site. Only 26 subjects appeared in both cohorts. In-hospital mortality was significantly higher in the administrative cohort than the registry cohort (91% vs. 61%, P < 0.001), and hospital discharge disposition of survivors was less favorable (P < 0.001). Neither difference persisted after excluding subjects surviving <6h. Conclusion Compared to a prospective registry, ICD-9CM codes are an insensitive method to identify OHCA subjects. Moreover, ICD-9CM codes identify a biased sample of the OHCA population with higher mortality.

Long-term survival benefit from treatment at a specialty center after cardiac arrest

“…For patients identified by ICD-9CM code, we confirmed the diagnosis of SCA with a structured chart review, which we have confirmed to be essential for accurate case ascertainment. [23] We included patients resuscitated from in-hospital or out-of-hospital SCA who survived to hospital discharge, and excluded those with SCA secondary to surgical etiology such as trauma, or neurological catastrophe. We extracted name, sex, date of birth, race, marital status, state of last known residence, and social security number, and used these data to query the National Death Index (NDI) 2013 NDI Final File to obtain long-term survival data.…”

Cardiac arrest risk standardization using administrative data compared to registry data

“…A recent study called into question the utility of administrative data for identifying out-of-hospital CA. [ 51 ] Investigators queried ICD-9 codes for cardiac arrest as well as VF, paroxysmal ventricular tachycardia, ventricular flutter, and respiratory arrest and found that only 40% of patients who had these ICD-9 codes had an out-of-hospital CA upon chart review. However, 94% of the CAs in our registry matched to administrative data, although there were some significant differences between the patients who were matched and those who were not.…”

Major interventions are associated with survival of out of hospital cardiac arrest patients - a population based survey

“…First, the data was obtained from an administrative database, which has been shown in the past to have inaccuracies when used for cardiac arrest research. (40) To overcome this, procedures and drugs administrated during resuscitation were another key element in data selection in addition to ICD-9 diagnosis code. Only those with attempts in resuscitation were enrolled in the analysis.…”