Outcomes of hospitalizations for common illnesses associated with a comorbid heat-related illness in the United States, 2001–2010

This research examines whether inpatients with common illnesses and comorbid heat-related illness (HRI) suffer worse health outcomes and use more hospital resources than similar patients without a diagnosed HRI. We used the Nationwide Inpatient Sample, 2001–2010 to compare outcomes, including inpatient length of stay, number of procedures, total charges, discharge status and death, for hospitalization of common illnesses with and without HRI. We used bivariate and multivariable regressions to identify risk factors for health outcomes among inpatients with common illnesses and comorbid HRI. Stratified analyses examined outcomes according to sociodemographics and hospital characteristics to further identify specific risk factors. Among inpatients with respiratory illnesses, negative outcomes were more frequent when a comorbid HRI was present. Additionally, inpatients with cardiac diseases showed increased mortality when a comorbid HRI was present. Overall, comorbid HRI was not associated with worse outcomes among the other common illnesses analyzed. While heat may precipitate hospital admissions for renal and diabetic conditions, these conditions have similar outcomes whether or not a HRI is present. However, comorbid HRI is associated with worse outcomes for respiratory illness hospitalizations and higher risk of death among cardiac disease hospitalizations.