Data source
We obtained data from the Nationwide Inpatient Sample (NIS) Database
from 2010 to 2017. The Agency for Healthcare Research and Quality
sponsors the NIS as part of the Healthcare Cost and Utilization Project.
The NIS is the largest publicly available all-payer inpatient healthcare
database designed to produce national estimates of inpatient
utilization, access, cost, quality, and outcomes. Unweighted, it
contains data from more than 7 million hospital stays each year.
Weighted, it estimates more than 35 million hospitalizations nationally.
The data include diagnosis and procedure codes from the International
Classification of Diseases, Ninth and Tenth Revision, Clinical
Modification (ICD-9-CM and ICD-10-CM), and Clinical Classifications
Software diagnosis and procedure classifications. The Institutional
Review Board at the University of Pittsburgh evaluated this study and
deemed it not to qualify as human subject research. The research team
completed relevant HCUP training modules and signed the NIS Data Use
Agreement.