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.