Objective: To determine the accuracy of ICD-9-CM external-cause-of-injury codes (e-codes) assigned to the medical records of injured patients treated in an ED and released.
Methods: A comparison was made of routine coding and expert recoding of medical records generated in the ED for a convenience sample of patients treated for injuries within 24 hours of injury occurrence and subsequently released from the ED. The medical record was handwritten and subsequently coded by three medical records coders (MRCs). The e-coded charts were sent to an external medical record consultant (expert), who was blinded to the codes previously assigned. The expert reading was used as the criterion standard. Accuracy was measured using a kappa statistic, and errors were described.
Results: Of 126 available patient charts, 108 (85.7%) were assigned e-codes by MRCs. The expert assigned two codes to (double-coded) 67 patients, while the MRCs double-coded only one patient. The additional code was usually a "place of occurrence code." In 60 cases (55.6%), the expert code exactly matched the MRC code; kappa = 0.462. Of the 48 mismatches (44.4%), 20 (41.7%) were e-coded in the wrong category, 20 (41.7%) were e-coded in the correct category but with incorrect specificity of information, either too specific or not specific enough, and eight (16.6%) had combined coding errors.
Conclusion: The accuracy of e-codes assigned to ED records was moderate in this single institution analysis. Errors were predominantly related to the specificity of the code, but some e-codes were in the wrong category. There are implications for injury surveillance and research. E-code assignment must be standardized and applied uniformly to obtain accurate codes. Automation of e-coding could improve accuracy and consistency of codes. National and international epidemiologic studies of cause of injury among ED patients will be severely hampered until e-code assignment can be better standardized.