US emergency care patterns among nurse practitioners and physician assistants compared with physicians: a cross-sectional analysis.

While U.S. NPs/PAs-alone used less care and low-value advanced diagnostic imaging, the NP/PA-physician combination used more care and low-value advanced diagnostic imaging than physicians alone. Findings were reproduced among EDs where nearly all NP/PA visits were collaborative with physicians, suggesting that NPs/PAs seeing more complex patients used more services than physicians alone, but the converse might be true for more straightforward patients.