Thomas J. Kim, MD, MPH Roger B. Trent, Ph.D. California Department of Public Health

1. Heat-Related Deaths Associated with a Severe Heat Wave — California, July 2006California Public Health Association—North March 2008 Thomas J. Kim, MD, MPH Roger B. Trent, Ph.D. California Department of Public Health Climate Change Public Health Impacts Assessment and Response Collaboration

2. July 20, 2006 Heat Waves as Environmental Disasters

3. July 2006 California Heat Wave • July 15 – August 1 • ≥3 days of ≥100° F shade temperature • ≥2 days of ≥105° F heat index • Record breaking maximum temperatures • High minimum temperatures • Long duration

4. Heat-Related Illness is a Continuum • Heat stress and exhaustion • Cramping • Heavy perspiration • Weakness • Heat Stroke • Core body temperature >104°F • Multi-organ system dysfunction • Often fatal despite treatment

5. Risk Factors in Heat-Related Deaths • Exertion • Dehydration • Infant or Age >60 • Lack of air conditioning • Social isolation • Chronic diseases (CVD, COPD) • Cognitive and mobility impairments • Low socio-economic status • Housing characteristics

6. Objectives of Study • Describe heat-related deaths in California • Provide data on risks to help plan response • Not an “excess mortality” study to statistically estimate the effect of the heat wave on death rates

7. Methods • Case series • Coroner reports • Investigative narrative • Toxicology • Abstraction form • Denominator data from 2005 US Census estimates • Compared to California mortality data

8. Case Definition • Death of a state resident of any age • Death between July 15 – August 1 • Underlying or contributory cause of death • No evidence of trauma and at least one of the following: • Core body temperature ≥ 105°F (≥ 40°C) • Decomposed body, person last seen alive at onset of heat wave • High environmental temperature at death scene

9. Heat-Related Death in California, July 15 – August 1, 2006 (n=140) Northern Central Valley (Willows) Number of Cases Date of Death in July 2006

10. Heat-Related Deaths in Counties with ≥10 Deaths, July 15 – August 1

11. High Temperatures, Heat Deaths, July 2006

12. Demographics of Heat-Related Deaths (n=140)

13. Distribution of Heat-Related Deaths by Age(Range: 10–98) Percent Age

14. Age Distribution of Heat-Related Deaths by Hispanic Ethnicity

15. Air Conditioning (AC) Use Among Indoor Decedents (n=96)

16. Air Conditioning (AC) Use Among Indoor Decedents (n=96)

17. Recent Social Contact Before Death of Decedents Who Lived Alone 140 Total decedents 34 Lived with others 41 Unknown 65 Lived alone 29 without known recent social contact 36 (55%) with known recent social contact 17 Seen > 24 hrs 19 (29%) seen ≤ 24 hours

18. Chronic Disease Conditions Among Heat-Related Deaths

19. Limitations • Lack of information on decedents • Knowledge of alerts and risk reduction steps • Presenting symptoms • Coroner reports • Not designed specifically for public health use • Data on deaths, not on heat morbidity

20. Discussion • 71% had one or more commonly known risk factors • Non-use of functioning air conditioners in 13% • Possible ineffective assessment and intervention by social contact prior to death • Younger age in Hispanic decedents

21. Recommendations • Clearly define threshold for intervention by social contacts • Not to wait for symptoms • Based on forecast and risk factors • Concentrate on populations and areas of special risk • Conduct active surveillance or case control study in heat illness • AC use • Tailor prevention messages for high risk groups

22. Did we count them all? Heat stroke is much easier to document than is heat that exacerbates existing conditions and causes higher death rates in general. Physician diagnosis Coroner determination Heat Exhaustion Heat Stroke

23. Coroner death case series They investigate possible homicides, suicides, accidents (including heat) and unexpected deaths to persons not seen by a physician in past 20 days. Based on investigation of death circumstances Evidence of heat stroke Method: precise counts of specific persons Excess mortality study “Heat stress” “Harvesting effect” “Forward displacement of deaths” “Statistical excess or spike” Method: compare number of deaths on hot days to some baseline of days with “normal” weather Two approaches to epidemiology of heat deaths

24. High Priority Studies for Heat Emergencies • Death case series: done • Excess mortality estimate: planned (when all death data for 2006 are available) • Studies of risks and protective factors for nonfatal morbidity • To help public avoid illness and protect health • To avoid straining ERs and EMS

25. California Department of Public Health Gayle Windham, PhD Barbara Materna, PhD Paul English, PhD Helene Margolis, PhD Dan Smith, Dr.PH Kathleen Fitzsimmons, MPH Lawrence Berkeley National Lab Tom McKone, PhD Centers for Disease Control and Prevention Janet Blair, PhD, MPH Randolph Daley, DVM, MPH George Luber, PhD Bruce Gutelius, MD Tom Weiser, MD Acknowledgments