Proportion of injury deaths with unspecified external cause codes: A comparison of Australia, Sweden, Taiwan and the US

Background: The proportion of injury deaths with unspecified external cause codes has been used as an indicator of the level of comprehensiveness and specificity of information on death certificates provided by certifiers. Objective: To compare the proportion of unspecified external cause codes across countries. Methods: Multiple-cause-of-death mortality data for people who died in 2001 due to external causes in Australia, Sweden, Taiwan and the USA were used for this international comparison study. The proportion of injury deaths coded as due to an unspecified external cause (International Statistical Classification of Diseases and Related Health Problems, Tenth Revision, ICD-10, chapter XX) to all injury deaths in each block was calculated. Results: Sweden (33%) had the highest proportion of use of the least specific code (ICD-10 code X59 exposure to unspecified factor), followed by Australia (17%), Taiwan (13%) and the USA (7%). More than two-thirds of the deceased for whom an ICD-10 code X59 was assigned in Sweden and Australia were those aged ≥65 years, and more than half of them had femoral fractures. The percentage of use of the unspecified codes within specific groups of external causes was relatively high for falls and unintentional drowning. Conclusions: Caution should be used in examining the compensatory effects of the unspecified external event code (ICD-10 code X59) on specific external causes (especially falls) when making international comparisons. Efforts are needed to educate certifiers to report sufficient information for specific coding so as to provide more useful information for injury prevention.