Source of data

The National Inpatient Sample (NIS) contains a 20% stratified sample of community hospitals in the United States and provides sampling weights to calculate national estimates.¹² This sample size is determined by the Agency for Healthcare Research and Quality (AHRQ) based on their experience with other similar databases.¹³ This sample is weighted to obtain national estimates with high accuracy using weights published by Healthcare Cost and Utilization Project (HCUP).¹² Individuals’ hospitalizations are de-identified. Each de-identified hospitalization information that includes demographics, comorbidities, LOS, cost of care and outcomes.