Characterizing Heat Health Outcomes and Informing Public Health Interventions with Medical Claims Data in California

Summary: (Preprint) manuscript and data extracts for "Medical Claims Data Characterizes Heat Health Risk for Low-Income and Agricultural Communities in California" by Avery Bick PhD, Gina Hervey JD, and Jenny Suckale PhD. See the manuscript file for more information on methods for processing medical claims and socioeconomic data. See code and workflow on Redivis at https://doi.org/10.71778/ywt4-2r72 Abstract: Heat exposure is a significant cause of morbidity and mortality around the world that is expected to worsen with climate change. In California, efforts to map the health risks of heat exposure have focused mainly on compiling indices that assess heat vulnerability theoretically, rather than empirically. Here, we use complete Medicaid claims data from 2011-2019 to map heat impacts for low-income Californians at a ZIP code scale. We find that the top 10% of ZIP codes by heat-related claim rates tend to have lower median income, a higher percentage of farm workers, and a higher rate of mobile homes, compared to the lower 90% of ZIP codes. We find that heat-related claim rates increase 24.4% for every 1 C in majority cropland areas, compared to 20.6% for every 1 C in majority built-up areas. Comparing heat-related claim rates against three common heat and socioeconomic vulnerability indices, we find that two have a weak to moderate positive correlation, while the third is weakly negatively correlated. These results highlight the importance of considering medical claims data when mapping heat impacts and designing interventions to reduce heat-related health risks and public costs. Files: Bick_Manuscript.pdf Preprint manuscript file Bick_SI.pdf Paper supporting information: Parameters of BYM2 claim count smoothing algorithm, OLS regression model results for temperature effects on claims by land use type, and effects of the 2017 Central Valley Heat Wave on temporal claim counts. CA_Medicaid_heat_related_claims_by_age_sex_2011_2019.csv Description: Total California Medicaid heat-related claim counts from 2011-2019, bucketed by age and sex. Note that claim counts reduce sharply after age 65 due to enrollment in Medicaid as the primary provider. Fields: Patient_Sex Age Heat_Related_Claim_Count CA_Medicaid_heat_related_claims_by_zip_2011_2019.csv Description Total California Medicaid heat-related claim counts and rates based on 2011-2019 Medicaid claim data, along with BYM2-smoothed rates and covariate environmental and socioeconomic data. Fields: ZIP Patient Residential ZIP codes Mean_Eligibles The mean monthly Medicaid enrollment in the ZIP between 2011-2019. Heat_Illness_Claims Raw counts of heat-related Medicaid claims in the ZIP. Includes all ICD 9 and 10 codes under "Effects of Heat & Light". Small cells of 1-15 claim counts in a ZIP are removed. Raw_Heat_Claims_per_Eligible Raw rates of heat-related Medicaid claims in the ZIP. Includes all ICD 9 and 10 codes under "Effects of Heat & Light". Rates based on small cells of 1-15 claim counts in a ZIP are removed Category Bucket representing range of claim counts in a ZIP. Color Color for plotting purposes. BYM_Expected_Cases Expected cases by ZIP based on BYM2 smoothing. BYM_Smoothed_Rate Expected rate by ZIP based on BYM2 smoothing and Mean_Eligibles. BYM_Smoothed_Rate_HDI_3 Low end of Bayesian credible interval for the BYM2 rate of heat related claims. BYM_Smoothed_Rate_HDI_97 High end of Bayesian credible interval for the BYM2 rate of heat related claims. Median_Household_Income Total_Farm_Workers Total agricultural, forestry, and fishing workers in a ZIP, derived from 2015-2019 American Community Survey ZCTA data Percent_Farm_Workers Percent of agricultural, forestry, and fishing workers in a ZIP of total workforce, derived from 2015-2019 American Community Survey ZCTA data MH_Spaces Number of mobile home spaces per ZIP code from records of active mobile home parks in 2024 from the California Department of Housing and Community Development MH_per_Eligible Rate of mobile home spaces per Medicaid eligible by ZIP Most_Common_LULC Land cover that is most common in each ZIP, derived from ESA WorldCover 2020 Tree_Cover_Fraction Percent of ZIP covered by tree cover, derived from ESA WorldCover 2020 Built_Up_Fraction Percent of ZIP covered by built-up area, derived from ESA WorldCover 2020 Cropland_Fraction Percent of ZIP covered by cropland, derived from ESA WorldCover 2020 Bare_Fraction Percent of ZIP covered by bare land, derived from ESA WorldCover 2020 Average_Max_Daily_Temperature_C Average max daily temperature by ZIP from 2011-2019, derived from DayMet