“…To identify care settings, we used a combination of fields on a given claim to classify it as occurring in a particular care setting: inpatient, hospital outpatient, physician office, EDs, UCCs, and other location (the exact definitions are summarized in Appendix Table A2). Our methods for identifying UCCs are described in greater detail in a previous publication (Buttorff et al, 2020), but in summary, we classified claims as billed from a UCC if they identified in NPPES as an organizational NPI with the UCC taxonomy codes in primary or secondary position (261QE0002X; 261QU0200X) and used a place of service code of 20 (a Center for Medicare & Medicaid Services (CMS) classification of UCCs that is also used by many commercial insurers), or billed one of the UCC Health Care Common Procedure Code System codes (S0983; S9088) in at least 10% of claims. This method of identifying UCCs had a positive predictive value of 87% and identified 8,261 UCCs in NPPES, in line with industry estimates.…”