Date of Degree


Document Type


Degree Name



Public Health


Grace Sembajwe

Subject Categories

Environmental Health and Protection | Epidemiology | Public Health Education and Promotion


Climate Change, Heat morbidity, Heat Wave, Hospitalization


The objective of this dissertation was to identify individual and environmental risk factors, investigate outcomes and hospital resource use, including costs, and document the pattern of heat-related illness hospitalizations in the United States. The main data source for the study population was the 2001-2010 Nationwide Inpatient Sample (NIS). The study population for heat-related illnesses (HRIs) consists of patients in the NIS with at least one diagnosis of a heat-related illness (ICD-9 codes 992.0 - 992.9) from 2001 to 2010. Outcome analysis included a study population of patients who had primary or secondary diagnoses of diabetes, cardiovascular diseases, respiratory illnesses, nephritic illnesses and acute renal failure along with a diagnosis of a heat-related illness. Outcomes for costs were calculated and adjusted using the medical consumer price index for 2013. Data on air conditioner use and total cost of electricity use from air conditioning was derived from the Residential Energy Consumption Survey. This study identified a number of previously unknown risk factors for heat morbidity HRI, including age greater than 40, males and hospitalization in rural areas and small urban clusters. Additionally, stratified analyses of outcomes further identified specific risk factors among vulnerable populations. Elevated risk of negative health outcomes and increased hospital resource use was seen in patients diagnosed with common comorbidities, in particular those of a lower socioeconomic status, minority and most age groups with diagnoses of cardiac and respiratory diseases with a HRI. Analyses of costs showed substantial costs associated with hospitalizations due to heat-related illnesses with the average mean cost approximately $52.7 million while the total aggregate cost for the time period at just over half a billion dollars. Projected estimates for the average yearly cost of these hospitalizations in the future climate with estimates around half a billion US dollars by the late-21st century.

In conclusion, the study revealed a number of risk factors and negative health outcomes associated with hospitalizations of heat-related illnesses. These findings provide additional scientific evidence that heat-related illnesses will continue to rise and will continue to be a public health burden as climate changes increase in frequency and intensity of extreme weather events.