Identifying individual risk factors and documenting the pattern of heat-related illness through analyses of hospitalization and patterns of household cooling.
BACKGROUND
As climate change increases the frequency and intensity of extreme heat events researchers and public health officials must work towards understanding the causes and outcomes of heat-related morbidity and mortality. While there have been many studies on both heat-related illness (HRI), there are fewer on heat-related morbidity than on heat-related mortality.


OBJECTIVE
To identify individual and environmental risk factors for hospitalizations and document patterns of household cooling.


METHODS
We performed a pooled cross-sectional analysis of secondary U.S. data, the Nationwide Inpatient Sample. Risk ratios were calculated from multivariable models to identify risk factors for hospitalizations. Hierarchical modeling was also employed to identify relationships between individual and hospital level predictors of hospitalizations. Patterns of air conditioning use were analyzed among the vulnerable populations identified.


RESULTS
Hospitalizations due to HRI increased over the study period compared to all other hospitalizations. Populations at elevated risk for HRI hospitalization were blacks, males and all age groups above the age of 40. Those living in zip-codes in the lowest income quartile and the uninsured were also at an increased risk. Hospitalizations for HRI in rural and small urban clusters were elevated, compared to urban areas.


CONCLUSIONS
Risk factors for HRI include age greater than 40, male gender and hospitalization in rural areas or small urban clusters. Our analysis also revealed an increasing pattern of HRI hospitalizations over time and decreased association between common comorbidities and heat illnesses which may be indicative of underreporting.
School of Public Health, City University of New York (CUNY), New York, United States of America.
Michael T
MT
Schmeltz
School of Public Health, City University of New York (CUNY), New York, United States of America; Hunter College, City University of New York (CUNY), New York, United States of America.
Grace
G
Sembajwe
Hunter College, City University of New York (CUNY), New York, United States of America; CUNY Institute for Sustainable Cities, New York, United States of America.
Peter J
PJ
Marcotullio
School of Public Health, City University of New York (CUNY), New York, United States of America; Health and Nutrition Sciences, Brooklyn College, City University of New York (CUNY), Brooklyn, NY, United States of America.
Jean A
JA
Grassman
School of Public Health, City University of New York (CUNY), New York, United States of America; Hunter College, City University of New York (CUNY), New York, United States of America.
David U
DU
Himmelstein
School of Public Health, City University of New York (CUNY), New York, United States of America; Hunter College, City University of New York (CUNY), New York, United States of America.
Stephanie
S
Woolhandler
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D057231:Climate Change; D003430:Cross-Sectional Studies; D055874:Extreme Heat; D005260:Female; D018882:Heat Stress Disorders / Q000453:epidemiology / Q000209:etiology*; D006760:Hospitalization; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D055815:Young Adult