Heat-Related Illness: Data Dashboard and Guidance

Data are from participating Louisiana (LA) Emergency Departments. Approximately 90% of Louisiana EDs provide data. Data are transmitted and processed via the National Syndromic Surveillance Program’s BioSense Platform. BioSense is a cloud-based platform that hosts the Electronic Surveillance System for the Early Notification of Community-based Epidemics, or ESSENCE, a web-based syndromic surveillance analysis system. Note that counts might change over time due to several factors: new updates and messages are continuously received, reporting facilities are onboarded and offboarded, and case query definitions are modified and refined.

Each case represents an ED visit for heat-related illness. An individual may have more than one ED visit. Records are selected using a built-in Essence query that searches the Chief Complaint (i.e., the patient’s stated reason for visit), Admit Reason (i.e., the provider’s noted reason for admission), and Discharge Diagnosis fields for text and ICD codes associated with heat exhaustion, heat exposure, heat cramps, heat stroke or hyperthermia. The Clinical Impression and Triage fields were added to the syndrome query to increase the number of cases captured.

While syndromic surveillance is a valuable near real-time data source for assessing the impacts of HRI in Louisiana, it is accompanied by some limitations that should be considered when interpreting the data. Not all ED visits in the state are included in the data analyzed (approximately 90% of EDs report data). Also, the amount of ED data received by the syndromic system may change over time due to the onboarding and off-boarding of facilities, changes in electronic health reporting systems and data outages for various reasons. This limitation should be considered when analyzing trends over time. Patients seen outside of EDs, such as at urgent care centers or by emergency medical services without transport to a hospital, are not captured. Records in ESSENCE are not verified using clinical standards to definitively classify them and so do not represent clinically confirmed diagnoses. Some cases are identified from pre-visit information. These fields may be inaccurately or incompletely reported which could result in misclassification of HRI ED visits. An example of this issue lies within the Chief Complaint category, as it relies on self-reporting and may provide ambiguous information. Data are retrieved and reported based on location of treatment facility, except for the number of HRI ED visits by parish, which is reported based on the patient’s parish of residence. While the facility location is a useful proxy for the patient’s location, it represents the location where the patient sought care which may differ from the location where the patient became ill.

Daily temperature estimates are created using nClimGrid-Daily. nClimGrid-Daily is a gridded (0.0417° or 5-km) dataset offering daily minimum, maximum, and average temperatures from 1951 to the near present. Data are maintained by the National Oceanic and Atmospheric Administration’s (NOAA) National Centers for Environment Information (NCEI). For a detailed description of the dataset, please view “Daily High-Resolution Temperature and Precipitation Fields for the Contiguous United States from 1951 to Present” by Durre et al., (2022).

Daily statewide and regional temperature estimates are created by averaging all grids within the state and regional boundaries based on Census TIGER/Line Shapefiles. The grids are created by an estimation algorithm using National Weather Service Cooperative Observer Program stations and Automated Surface Observing Systems stations. Both are National Weather Service and NCEI approved. The data are extensively quality-controlled.

Daily values represent prevailing conditions during the 24 hours ending during the morning on the observation day. For example, the estimates for April 1st represent conditions from the morning of March 31st ending during the morning of April 1st. The data generally have a latency of 1-3 days and preliminary estimates may be subject to change.  

Code development and testing for temperature data were done by the Southern Climate Impacts Planning Program.