Real-time mortality surveillance during and after Hurricane Sandy in New York City: Methods and lessons learned

Background: In New York City (NYC), 94% of deaths are reported via an electronic death registration system (EDRS). During Hurricane Sandy and its aftermath, the NYC Health Department conducted real-time mortality surveillance to identify directly hurricane-related deaths and other excess mortality. Objectives: Describe NYC's real-time mortality surveillance methods and lessons learned. Methods: We reviewed surveillance methods, measured reporting timeliness, and identified challenges. System Description: NYC mandates death certification (clinician's report of decedent's name, sex, time/date/place of death, and free-text cause of death) within 24 hours and registration (includes decedent's address and demographics) within 72 hours. For this event, ad hoc SQL queries were required to extract needed EDRS data. Newly developed mortality reports compared daily certified death counts with 2010–2011 averages, categorized registered deaths by cause and flood levels, and provided additional descriptive tables. Aside from free-text searches for injury-related terms, cause-of-death analyses occurred after registration and on-site ICD-10 coding. To categorize deaths by census-tract flooding levels, timely address geocoding was conducted post-registration. Results: EDRS remained operational during and after the hurricane. For Oct 29–Nov 10, 2012, average time to certification was 0.5 vs. 1.5 days for 2010–2011, while average time to registration was 4.6 vs. 3.6 days for 2010–2011. Analytical challenges included restricting 2010–2011 comparison data by certification/registration date due to reporting lag and accounting for nursing home evacuations in geographic comparisons. Free-text searches for injury-related terms only identified deaths already reported as hurricane-related outside of EDRS by the medical examiner's office. Operational challenges included staff displacement and duplicate pre-registration death certifications. Discussion: Timely EDRS data allowed for NYC's successful real-time mortality surveillance. Jurisdictions conducting such surveillance should mandate rapid death certification/registration; retain nosologists for timely ICD-10 coding; ensure adequate staff to extract, geocode, and analyze data; and use pre-registration death certificates to enhance timeliness.