Correspondence

Deaths in the Chicago Heat Wave

N Engl J Med 1996; 335:1848-1850December 12, 1996

Article

To the Editor:

From the report by Semenza et al.1 and the accompanying editorial by Kellermann and Todd2 on the risks associated with heat waves (July 11 issue), it seems that the vocabulary of risk factors has shifted over the past 15 years. When a similar report was published after the July 1980 heat wave in St. Louis and Kansas City, Missouri, the researchers identified nonwhite race and poverty as significant risk factors for heat-related death.3 In 1996, Semenza et al. identify social isolation as a risk factor. Although the labels have changed, the risk groups seem largely the same. Does the category of social isolation relate to the earlier categories? Are nonwhite race and poverty still meaningful risk factors, or is social isolation a more precise and accurate term?

Over the past 10 years, the specific problem of urban heat waves has been viewed in the broader context of possible global climatic change.4 Models show that during the next century, both global warming and increased climatic instability may greatly increase heat-related mortality in the United States and other industrialized countries. Physicians and public health officials need to be aware that heat waves, typically seen as local and unavoidable, may actually be part of a preventable global process.

David Shumway Jones
Harvard Medical School, Boston, MA 02115

4 References

1. 1

   Semenza JC, Rubin CH, Falter KH, et al. Heat-related deaths during the July 1995 heat wave in Chicago. N Engl J Med 1996;335:84-90
   Full Text | Web of Science | Medline

2. 2

   Kellermann AL, Todd KH. Killing heat. N Engl J Med 1996;335:126-127
   Full Text | Web of Science | Medline

3. 3

   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;247:3327-3331
   CrossRef | Web of Science | Medline

4. 4

   Stone R. Global warming: if the mercury soars, so may health hazards. Science 1995;267:957-958
   CrossRef | Web of Science | Medline

To the Editor:

In their report on heat-related deaths in Chicago in July 1995, Semenza et al. do not mention the most common medications the patients were taking. Specifically, how many were taking angiotensin-converting–enzyme inhibitors? It is well known that in patients taking such drugs, marked dehydration can lead to excessive hypotension, with dire consequences.

Jose Cervantes, M.D.
121-20 135th Ave., South Ozone Park, NY 11420

Author/Editor Response

Dr. Semenza replies:

To the Editor: Jones notes that race was not a risk factor for heat-related mortality in our study. Since our case subjects and controls were matched according to neighborhood, which in Chicago correlates to some degree with race, we could analyze risk factors pertaining to individuals and households, but not race or ethnic group. Immediately after the heat wave, the Centers for Disease Control and Prevention enumerated all heat-related deaths recorded by the Cook County Medical Examiner's Office and found that 49 percent of the persons who died were black, 46 percent were white, and 5 percent belonged to other racial or ethnic groups.1 That analysis was based on preliminary data, however. Researchers from the Chicago Department of Public Health are analyzing the complete data on heat-related deaths and comparing age-adjusted death rates according to race, but the results are not yet available.

We did not specifically address poverty as a risk factor. However, using surrogate information on socioeconomic status, such as data on living conditions (single-family home vs. apartment building, number of rooms, and ownership of an air conditioner), we found that poverty remained a major underlying risk factor for heat-related mortality. Our study identified social isolation among the elderly as an important risk factor for heat-related deaths in Chicago. Comprehensive response plans by health officials should focus on these high-risk populations to prevent such deaths.

Cervantes's inquiries about the medications used by the people who died highlights an important issue to which we devoted a considerable amount of effort in the course of the study. Information was collected on the prescription and nonprescription medications the study subjects used, and when possible, we inventoried the contents of their medicine cabinets. However, because we relied on surrogates to provide information on the case subjects, in many instances it was not possible to reconstruct accurately which medications were used. Thus, the precise number of people who used angiotensin-converting–enzyme inhibitors cannot be determined. A study of the medications used by patients with nonfatal heatstroke could shed light on this important issue.

Jan C. Semenza, Ph.D., M.P.H.
Centers for Disease Control and Prevention, Atlanta, GA 30341-3724

1 References

1. 1

   Heat-related mortality -- Chicago, July 1995MMWR Morb Mortal Wkly Rep 1995;44:577-579
   Medline

Citing Articles (1)

Citing Articles

1. 1

   Ning Zhang, Lianfang Zhu, Yan Zhu. (2011) Urban heat island and boundary layer structures under hot weather synoptic conditions: A case study of Suzhou City, China. Advances in Atmospheric Sciences 28:4, 855-865
   CrossRef