Concordance between coding sources of burn size and depth across Australian and New Zealand specialist burn services

Abstract

Background The percentage of total body surface area (%TBSA) burned and burn depth provide valuable information on burn injury severity. Objective This study investigated the concordance between The International Statistical Classification of Diseases and Related Health Problems, Tenth Revision, Australian Modification (ICD-10-AM) codes and expert burn clinicians in assessing burn injury severity. Method We conducted a retrospective population-based review of all patients who sustained a burn injury between July 1, 2009, and June 30, 2019, requiring admission into a specialist burn service across Australia and New Zealand. The %TBSA burned (including the percentage of full thickness burns) recorded by expert burn clinicians within the Burns Registry of Australia and New Zealand (BRANZ) were compared to ICD-10-AM coding. Results 20,642 cases (71.5%) with ICD-10-AM code data were recorded. Overall, kappa scores (95% confidence interval [CI]) for burn size ranged from 0.64 (95% CI 0.63–0.66) to 0.86 (95% CI 0.78–0.94) indicating substantial to almost perfect agreement across all %TBSA groups. When stratified by depth, the lowest agreement was observed for < 10% TBSA and < 10% full thickness (kappa 0.03; 95% CI 0.02–0.04) and the highest agreement was observed for burns of ≥ 90% TBSA and ≥ 90% full thickness (kappa 0.72; 95% CI 0.58–0.85). Conclusion Overall, there was substantial agreement between the BRANZ and ICD-10-AM coded data for %TBSA classification. When %TBSA classification was stratified by burn depth, greater agreement was observed for larger and deeper burns compared with smaller and superficial burns. Implications Greater consistency in the classification of burns is needed.