Use of Death Certificates to Identify Tuberculosis-Related Deaths in Washington State

Abstract

Death certificates are routinely used to estimate tuberculosis (TB) mortality rates. The validity of International Classification of Diseases, Tenth Revision (ICD-10) codes and text cause of death data for this purpose is uncertain. To evaluate the accuracy of ICD-10 coded and text cause of death data in identifying TB-related deaths in Washington State. Cross-sectional descriptive study comparing TB-related deaths detected through Washington State death certificates to TB-related deaths identified in the Washington State TB registry during 2009-2010. Sensitivity and positive predictive value of ICD-10 coded and text cause of death definitions in identifying TB-related deaths compared to the TB registry. All methods for identifying TB-related deaths using death certificate data overestimated the number of TB-related deaths compared to the tuberculosis registry. The positive predictive value ranged from 22% for a TB ICD-10 code as an underlying or multiple cause of death to 56% for TB listed in the direct cause of death text field. Seventeen (33%) of 51 subjects assigned with a TB ICD-10 code as an underlying or multiple cause of death had no evidence of TB on the death certificate and were not present in the TB registry. Death certificates were not highly predictive of TB-related deaths. Use of the direct cause of death text field was the most accurate method to identify a TB-related death when using death certificates. Specific ICD-10 coding algorithms may misclassify subjects as having died from TB.