Pregnant and scared, Natasha Valle went to a Tennova Healthcare hospital in Clarksville, Tenn., in January 2021 because she was bleeding. She didn’t know much about miscarriage, but this seemed like one.

In the emergency room, she was examined then sent home, she said. She went back when her cramping became excruciating. Then home again. Valle said it ultimately took three trips to the ER on three consecutive days, generating three separate bills, before she saw a doctor who looked at her bloodwork and confirmed her fears.

“At the time I wasn’t thinking, ‘Oh, I need to see a doctor,’ ” Valle said. “But when you think about it, it’s like, ‘Well — dang — why didn’t I see a doctor?’ ” It’s unclear if the repeat ER visits were due to delays in seeing a physician, or if that affected her care, but the experience worried her. And she’s still paying the bills.

The hospital declined to discuss Valle’s care, citing patient privacy. But 17 months before her three-day ordeal, Tennova had outsourced its emergency rooms to American Physician Partners, a medical staffing company owned by private equity investors. APP employs fewer doctors in its ERs as one of its cost-saving initiatives to increase earnings, according to a confidential company document obtained by KHN and NPR

This staffing strategy has permeated hospitals, and particularly emergency rooms, that seek to reduce their top expense: physician labor. While diagnosing and treating patients was once doctors’ domain, they are increasingly being replaced by nurse practitioners and physician assistants, collectively known as “midlevel practitioners,” who can perform many of the same duties and generate much of the same revenue for less than half the pay.

“APP has numerous cost saving initiatives underway as part of the Company’s continual focus on cost optimization,” the document says, including a “shift of staffing” between M.D.s and mid-level practitioners.

In a statement to KHN, American Physician Partners said this strategy is a way to ensure all ERs remain fully staffed, calling it a “blended model” that allows doctors, nurse practitioners and physician assistants “to provide care to their fullest potential.”

Researchers found that treatment by a nurse practitioner resulted on average in a 7% increase in cost of care and an 11% increase in length of stay, extending patients’ time in the ER by minutes for minor visits and hours for longer ones. These gaps widened among patients with more severe diagnoses, the study said, but could be somewhat mitigated by nurse practitioners with more experience.

The study also found that ER patients treated by a nurse practitioner were 20% more likely to be readmitted to the hospital for a preventable reason within 30 days, although the overall risk of readmission remained very small.

Yiqun Chen, who is an assistant professor of economics at the University of Illinois-Chicago and co-authored the study, said these findings are not an indictment of nurse practitioners in the ER. Instead, she said, she hopes the study will guide how to best deploy nurse practitioners: in treatment of simpler cases or in circumstances when no doctor is available.

.It’s not just a simple question of if we can substitute physicians with nurse practitioners or not,” Chen said. “It depends on how we use them. If we just use them as independent providers, especially … for relatively complicated patients, it doesn’t seem to be a very good use.”