Susceptibility to Heat-Related Fluid and Electrolyte Imbalance Emergency Department Visits in Atlanta, Georgia, USA

Abstract

Identification of populations susceptible to heat effects is critical for targeted prevention and more accurate risk assessment. Fluid and electrolyte imbalance (FEI) may provide an objective indicator of heat morbidity. Data on daily ambient temperature and FEI emergency department (ED) visits were collected in Atlanta, Georgia, USA during 1993-2012. Associations of warm-season same-day temperatures and FEI ED visits were estimated using Poisson generalized linear models. Analyses explored associations between FEI ED visits and various temperature metrics (maximum, minimum, average, and diurnal change in ambient temperature, apparent temperature, and heat index) modeled using linear, quadratic, and cubic terms to allow for non-linear associations. Effect modification by potential determinants of heat susceptibility (sex; race; comorbid congestive heart failure, kidney disease, and diabetes; and neighborhood poverty and education levels) was assessed via stratification. Higher warm-season ambient temperature was significantly associated with FEI ED visits, regardless of temperature metric used. Stratified analyses suggested heat-related risks for all populations, but particularly for males. This work highlights the utility of FEI as an indicator of heat morbidity, the health threat posed by warm-season temperatures, and the importance of considering susceptible populations in heat-health research.

Keywords: climate change; emergency department visits; fluid and electrolyte imbalance; heat morbidity; temperature.

Figure 1

Plots of estimated rate ratios for fluid and electrolyte imbalance ED visits in relation to various temperature increments from the 25th percentile reference for various temperature metrics in Atlanta during warm seasons (May–September), 1993–2012: (a) Maximum ambient air temperature; (b) Minimum ambient air temperature; (c) Average ambient air temperature; (d) Maximum apparent temperature; (e) Minimum apparent temperature; (f) Average apparent temperature; (g) Maximum heat index; (h) Minimum heat index; (i) Diurnal change in air temperature; (j) Diurnal change in apparent temperature. * RRs marked by asterisk are equivalent to those reported in Table 3 and represent the RR per IQR from the 25th to 75th percentile.

Figure 1

Plots of estimated rate ratios for fluid and electrolyte imbalance ED visits in relation to various temperature increments from the 25th percentile reference for various temperature metrics in Atlanta during warm seasons (May–September), 1993–2012: (a) Maximum ambient air temperature; (b) Minimum ambient air temperature; (c) Average ambient air temperature; (d) Maximum apparent temperature; (e) Minimum apparent temperature; (f) Average apparent temperature; (g) Maximum heat index; (h) Minimum heat index; (i) Diurnal change in air temperature; (j) Diurnal change in apparent temperature. * RRs marked by asterisk are equivalent to those reported in Table 3 and represent the RR per IQR from the 25th to 75th percentile.

Figure 2

Plots of estimated rate ratios for fluid and electrolyte imbalance ED visits in relation to various temperature increments from the 25th percentile reference for TMax by modifiers of interest in Atlanta during warm seasons (May–September), 1998–2012: (a) FEI by Sex; (b) FEI by White and Nonwhite Race; (c) FEI by Nonwhite Race Categories; (d) FEI with Comorbid Congestive Heart Failure (CHF) Present and Absent; (e) FEI with Comorbid Renal Disease Present and Absent; (f) FEI with Comorbid Diabetes Present and Absent; (g) FEI by Poverty Area; (h) FEI by Undereducated Area. * RRs marked by asterisk are equivalent to those reported in Table 5 and represent the RR per IQR from the 25th to 75th percentile.