Data Source
The data were obtained from the Nationwide Inpatient Sample (NIS) data set from 2005 to 201412. The NIS is a nationally representative survey of hospitalizations conducted by the Healthcare Cost and Utilization Project in collaboration with the participating states. It is the largest all-payer inpatient data set in the United States and includes a sample of US community hospitals that approximates 20% of all US community hospitals13. Each entry contains information on demographic details, including age, sex, insurance status, primary and secondary procedures, hospitalization outcome, total cost, and length of stay. The NIS database contains clinical and resource use information, with safeguards to protect the privacy of patients, physicians, and hospitals. The NIS database results have been shown to correlate well with other hospitalization discharge databases in the United States13. It has also been used to explain trends in other acute medical and surgical conditions14.