Sensitivity and Positive Predictive Value of Death Certificate Data Among Deaths Caused by Legionnaires' Disease in New York City, 2008-2013

Objectives: Death certificates are an important source of information for understanding life expectancy and mortality trends; however, misclassification and incompleteness are common. Although deaths caused by Legionnaires' disease might be identified through routine surveillance, it is unclear whether Legionnaires' disease is accurately recorded on death certificates. We evaluated the sensitivity and positive predictive value of death certificates for identifying deaths from confirmed or suspected Legionnaires' disease among adults in New York City.

Methods: We deterministically matched death certificate data from January 1, 2008, through December 31, 2013, on New York City residents aged ≥18 years to surveillance data on confirmed and suspected cases of Legionnaires' disease from January 1, 2008, through October 31, 2013. We estimated sensitivity and positive predictive value by using surveillance data as the reference standard.

Results: Of 294 755 deaths, 27 (<0.01%) had an underlying cause of death of Legionnaires' disease and 33 (0.01%) had any mention of Legionnaires' disease on the death certificate. Of 1211 confirmed or suspected cases of Legionnaires' disease, 267 (22.0%) matched to a record in the death certificate data set. The sensitivity of death certificates that listed Legionnaires' disease as the underlying cause of death was 17.3% and of death certificates with any mention of Legionnaires' disease was 20.9%. The positive predictive value of death certificates that listed Legionnaires' disease as the underlying cause of death was 70.4% and of death certificates with any mention of Legionnaires' disease was 69.7%.

Conclusions: Death certificates had limited ability to identify confirmed or suspected deaths with Legionnaires' disease. Provider trainings on the diagnosis of Legionnaires' disease, particularly hospital settings, and proper completion of death certificates might improve the sensitivity of death certificates for people who die of Legionnaires' disease.