The measures reported are based on ER procedure codes (CPT codes 99281-99285) for HCCI’s ESI population. They do not include the costs of other services patients received during their visit to the ER such as the cost of an injected drug. Therefore, these price and spending measures may not capture the entirety of what is typically thought of as an ER visit. Patients may often receive multiple ER CPT codes during the same visit. The yearly proportion of visits with multiple codes remained constant throughout the study period. When aggregated to the visit level, with each visit classified as high, dual, or low severity depending on the code(s) billed, we continued to see an increase in high severity, decrease in low severity, alongside a decline in overall ER visits. Average spending and prices are calculated from the actual amount paid for each claim line containing one of the 5 ER CPT codes. For more information about the HCCI dataset and the methodology of the calculations, see the Methodology page on the HCCI website.