ICD-10 codes do not accurately reflect ankle fracture injury patterns

Objective To determine the accuracy of International Classification of Disease Version 10 (ICD-10) coding for ankle fracture injury patterns. Design Retrospective cohort study Patients 97 adult patients with fractures about the ankle (rotational ankle fracture or distal tibia fracture) from 2016 to 2020, selected by stratified random sampling. Intervention Assignment of an ICD-10 code representative of a rotational ankle fracture, pilon fracture, or unspecified fracture of the lower leg. Outcome measurements Injury radiographs were reviewed by three authors to determine the correct code. Agreement between the correct code and the electronic medical record (EMR) assigned code was determined using kappa's statistic in the aggregate as well as percent agreement, sensitivity, specificity, and positive predictive value (PPV) between individual codes. Results 59 of 97 cases (60.8%) demonstrated discordance between the existing EMR and surgeon-assigned codes. Aggregate agreement between all codes was fair (K = 0.26). Lateral malleolus fracture codes demonstrated the highest PPV (0.91, 95% CI 0.72–0.99), while the lowest PPV was found for “other fractures of the lower leg” (0.05, 95% CI 0.0–0.24) and “other fracture of the fibula” (0.0, 95% CI 0.0–0.15). Generalized “other fracture” codes comprised 45% of EMR codes compared to only 6% of assigned codes (p Conclusion There is substantial discordance between existing EMR and surgeon-assigned ICD-10 codes for ankle fractures. Database research that relies on ICD-10 coding as a surrogate for primary clinical data should be interpreted with caution and institutions should make efforts to increase the accuracy of their coding.