Medical Examiner Summer Mortality Surveillance -- United States, 1979-1981

Sustained increases in summer temperature and humidity (heat waves) have been associated with extensive morbidity and mortality in the United States (1-4). Identification of high-risk groups and effective prevention measures for certain heat-related illnesses have allowed development of prevention programs (2,5-13). A pilot study designed to explore the utility and feasibility of using summer mortality statistics from medical examiners as a basis for indirect surveillance of heat-related illness was initiated in June 1981. The medical examiners of 16 major metropolitan areas, the National Climatic Center, and the National Weather Service provided CDC with the number of deaths each day and meteorologic measurements for the period June 1 - August 31, 1979-1981.

Average July temperatures were within 4F (2.2C) of normal at all surveillance sites in 1979 and 1981, but were as high as 8F (4.4C) above normal in 1980 at several surveillance sites due to a severe and widespread heat wave in July 1980. Deaths reported by medical examiners rose in mid-July 1980 in areas in which other health effects related to heat were severe (Figure 2). The proportionate increase in deaths in July 1980 over those reported in July 1979 correlated poorly with the average maximum temperature for July 1980, even after adjustment for the effect of humidity, but correlated well with the upward departure from the normal July temperature for each surveillance site.

The striking increase in deaths recorded by medical examiners and noted in several cities in association with the onset of unusually high temperatures suggests that these mortality data are useful in the prompt detection of outbreaks of heat-related illness. Further work is required to quantify the specificity and sensitivity of this method. Data collection will continue during the summer of 1982. Reported by LE Norton, MD, Office of the Jefferson County Medical Examiner, W Birch, DVM, State Epidemiologist, Alabama State Dept of Health; HH Karnitschnig, MD, Office of the Maricopa County Medical Examiner, JJ Sacks, MD, Acting State Epidemiologist, Arizona State Dept of Health Svcs; TT Noguchi, MD, Office of the Medical Examiner, Los Angeles, J Chin, MD, State Epidemiologist, California Dept of Health Svcs; RR Stivers, MD, Office of the Fulton County Medical Examiner, RK Sikes, DVM, State Epidemiologist, Georgia Dept of Human Resources; P Lipkovic, MD, Office of the Medical Examiner, Jacksonville, RA Gunn, MD, State Epidemiologist, Florida State Dept of Health; F Finger, National Weather Service, Camp Springs, Maryland; WU Spitz, MD, Office of the Medical Examiner, Detroit, NS Hayner, MD, State Epidemiologist, Michigan State Dept of Health; B Peterson, MD, Office of the Jackson County Medical Examiner, GE Gantner, MD, ME Case, MD, Office of the Medical Examiner, St. Louis, HD Donnell Jr, MD, State Epidemiologist, Missouri State Dept of Social Svcs; GS Green, MD, Office of the Clark County Coroner, WE Edwards, MD, State Epidemiologist, Nevada State Dept of Human Resources; E Gross, MD, Office of the Medical Examiner, D Sencer, MD, New York City Dept of Health, R Rothenberg, MD, State Epidemiologist, New York State Dept of Public Health; ML Nicodemus, National Climatic Center, Asheville, HR Wood, MD, Office of the Mecklenburg County Medical Examiner, MP Hines, DVM, North Carolina State Dept of Human Resources; FB Jordan, MD, Office of the Medical Examiner, Oklahoma City, MA Roberts, PhD, State Epidemiologist, Oklahoma State Dept of Health; LV Lewman, MD, Office of the Multnomah County Medical Examiner, JA Googins, MD, State Epidemiologist, Oregon State Dept of Human Resources; RL Catherman, MD, Office of the Medical Examiner, Philadelphia, EJ Witte, VMD, State Epidemiologist, Pennsylvania State Dept of Health; JT Francisco, MD, Office of the Medical Examiner, Memphis, RH Hutcheson Jr, MD, State Epidemiologist, Tennessee State Dept of Public Health; CS Petty, MD, Dallas County Institute of Forensic Science, CR Webb Jr, MD, State Epidemiologist, Texas State Dept of Health; Special Studies Br, Chronic Disease Div, Center for Environmental Health, CDC.

Editorial Note

Editorial Note: Large increases in numbers of deaths from stroke and ischemic heart disease as well as deaths from more obviously heat-related illness (e.g., heatstroke) have been reported in association with heat waves (14). Deaths caused by these conditions are often sudden, unlikely to be witnessed by a physician, and therefore likely to be investigated by a medical examiner. A population-based study of heat-related morbidity and mortality in 2 midwestern cities in 1980 showed that numbers of cases reported to medical examiners increased to a proportionately greater extent than did other indirect measures of impact on community health, e.g., total mortality, emergency room visits, and hospital admissions (2).

Surveillance of mortality data from medical examiners is simple, timely, and relatively inexpensive. Information that reflects the health of an entire city is rapidly available from a single source. Even the time required for post-mortem diagnosis does not delay collection of data.

Groups at high risk of having heatstroke are the elderly, infants 1 year of age, military recruits, persons exposed to high temperatures in the work place, the chronically ill or bedfast, the mentally ill, those taking antipsychotic or anticholinergic drugs, and alcoholics (2,5-7,9-12). Low socioeconomic status and residence in an urban area have also been associated with high risk of heatstroke (2,9). Studies of race and sex as predisposing factors for heatstroke have yielded inconsistent results (4,8,9). Deaths from heatstroke reflect 10%-50% of the increase in mortality associated with unusually high temperatures (2,14). Less is known about the risk factors for deaths not associated with heatstroke during a heat wave.

During a heat wave, prevention programs are best targeted toward persons at high risk of having heatstroke. Having home air conditioning and spending increased time in air-conditoned places have been associated with decreased risk, suggesting that air-conditioned heat wave shelters are of benefit. Reducing physical activity during hot weather has also been associated with decreased risk (5).

Adequate fluid intake is important in reducing the risk of having heatstroke (5,13). Although adequate salt intake with meals is important, salt tablets are of doubtful benefit and should not be taken unless prescribed by a physician (13). Alcohol consumption should be reduced or eliminated during very hot weather.

References

1. Environmental Data and Information Service. Impact assessment: U.S. social and economic effects of the great 1980 heat wave and drought. Washington, DC. National Oceanic and Atmospheric Administration, US Dept of Commerce 1980:12.

2. Jones TS, Liang AP, Kilbourne EM, et al. Morbidity and mortality associated with the July 1980 heat wave in St. Louis and Kansas City, Mo. JAMA 1982;247:3327-31.

3. CDC. Heatstroke--United States, 1980. MMWR 1981;30:277-9.

4. Henschel A, Burton LL, Margolies L, Smith JE. An analysis of the heat deaths in St. Louis during July, 1966. Amer J Public Health 1969;59:2232-42.

5. Kilbourne EM, Choi K, Jones TS, Thacker SB, and The Field Investigation Team. Risk factors for heatstroke: a case-control study. JAMA 1982;247:3332-36.

6. Danks DM, Webb DW, Allen J. Heat illness in infants and young children. A study of 47 cases. Brit Med J 1962;2:287-93.

7. Occupational Safety and Health Administration. Hot environments. Cincinnati: National Institute for Ocupational Safety and Health. (NIOSH publication no. 80-132). 1980.

8. Schuman SH. Patterns of urban heat-wave deaths and implications for prevention: data from New York and St. Louis during July, 1966. Environ Res 1972;5:59-75.

9. Ferris EB, Blankenhorn MA, Robinson HW, Cullen GE. Heat stroke: clinical and chemical observations on 44 cases. J Clin Investigation 1938;17:249-62.

10. Zelman S, Guillan R. Heat stroke in phenothiazine-treated patients: a report of three fatalities. Amer J Psychiat 1970;126:1787-90.

11. Wise TN. Heatstroke in three chronic schizophrenics: case reports and clinical considerations. Compr Psychiatry 1973;14:263-7.

12. Adams BE, Manoguerra AS, Lilja GP, Long RS, Ruiz E. Heat stroke associated with medications having anticholinergic effects. Minn Med 1977;60:103-6.

13. Pitts GC. Johnson RE, Consolazio FC. Work in heat as affected by intake of water, salt, and glucose. Am J Physiol 1944; 142:253-9.

14. Ellis FP. Heat illness. Trans Roy Soc Trop Med Hyg 1977;70:402-28.

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