BACKGROUND: Drug overdose is a major public health concern in New Mexico (NM) and the United States (US). Yet mortality is just one, and the most extreme, of the health outcomes associated with drug use. In NM, Emergency Department Opioid Overdose-Related Visits (ED-OORV) is a routine indicator assessed. On October 1, 2015, ED-ORV data was transitioned from International Classification of Disease, Clinical Modification, Ninth Edition (ICD-9-CM) to ICD-10-CM. The objective of this analysis is to assess that transition.
METHODS: ED-OORV was defined as any visit for which any diagnosis field contained codes pertaining to opioid poisoning: 965[.00-.02, .09] and E850[.0-.2] (ICD-9-CM), or T40[.0-.4, X1-X4] (ICD-10-CM). ICD-9-CM/ICD-10-CM transition was assessed by 1) creating ICD-9-CM and ICD-10-CM identifier variables, 2) segregating double-coded entries (coded in both ICD-9-CM and ICD-10-CM), and 3) creating a unique identifier for each of these entries. Opioid-overdose codes were used to identify opioid-overdose events among double-coded entries, using each ICD edition separately, and then comparing outputs. Crude and age-adjusted rates were calculated.
RESULTS: Over 100 entries had ICD-10-CM coding in the first two quarters of 2015. Over 18,000 entries were ICD-9-CM solely coded during the fourth quarter. Over 600 entries were coded in both ICD-9 and ICD-10 (double-coded). After adjusting for this transition, NM’s ED-OORV rate was 52.9 visits per 10,000 population.
CONCLUSIONS: The 2015 ED-OORV analysis revealed that some facilities started ICD-10-CM coding early, perhaps to familiarize themselves with the new system. In NM, large numbers of ICD-9-CM-only coded entries in the fourth quarter, advised against using exclusively ICD-10-CM, starting October 1st, to identify opioid overdose events. The assessment revealed that the least loss of information happened by processing double-coded entries using ICD-10-CM. This produced rates comparable to those obtained in prior years.