The Agency for Healthcare Research and Quality (AHRQ) has released the 2018 Nationwide Ambulatory Surgery Sample (NASS). The NASS is the largest all-payer ambulatory surgery database in the country. Unweighted, it contains approximately 7.7 million major ambulatory surgery encounters. Weighted, the NASS estimates approximately 10.1 million major ambulatory surgery encounters in the United States.

Constructed from the State Ambulatory Surgery Databases (SASD), the NASS tracks information about major ambulatory surgery encounters in hospital-owned facilities across the United States. The database provides information on patient characteristics, clinical diagnostic and surgical procedure codes, disposition of patients, total charges, expected source of payment, and facility characteristics. Major ambulatory surgeries are defined as selected invasive, therapeutic surgical procedures that typically require the use of an operating room and require regional anesthesia, general anesthesia, or sedation. Procedures intended primarily for diagnostic purposes are excluded.

Additional information is located on the NASS Overview Page. The 2018 NASS can be purchased through the HCUP Central Distributor.