Increase in deaths caused by HIV infection due to changes in rules for selecting underlying cause of death

With implementation of the International Classification of Diseases, 10th Revision (ICD-10), for U.S. vital statistics in 1999, the criteria for selecting HIV infection as the underlying cause of death were expanded. To estimate the effect of ICD-10 rules on the number of deaths attributed to HIV infection, we applied a simplified version of ICD-10 rules to data on causes of death from all U.S. death certificates for 1998 (previously classified by rules of the 9th revision of ICD [ICD-9]) and calculated the resulting increase in deaths for which HIV infection was selected as the underlying cause. Of the 17,186 deaths in 1998 with any mention of HIV infection on the death certificate, ICD-10 rules selected HIV infection as the underlying cause for 15,145, which was 1,719 (13%) more than the 13,426 for which it had been selected by ICD-9 rules. The proportional increase differed by demographic group, being less among non-Hispanic blacks (9%) and Hispanics (13%) than among non-Hispanic whites (18%). Thus, comparison of deaths attributed to HIV infection in 1999 or later with those in 1998 or earlier should take into account the changes in ICD rules for selecting the underlying cause of death.