In 2019, for people of all ages, private plans paid 84% of the $845 million hospital emergency rooms received for treating patients with appendicitis.

But private plans accounted for just 39% of the $52 million hospital emergency rooms received for checkups and other forms of "well person care."

At doctors' offices and clinics, private plans paid 73% of the appendicitis bills, 63% of the well-person care bills and 52% of the bills related to type 1 diabetes.

The paper appears behind a paywall on the website of the Journal of the Medical Association.

The authors want readers to use the paper to address questions such as why age-adjusted health care spending averages $13,332 per year in Nassau County, New York, and just $3,410 per year in Clark County, Idaho.

Employers and their benefits advisors could use the data to see how much more private payers are paying in a particular county than Medicare; identify procedures that are leading to huge out-of-pocket costs for private plan participants; find out where a procedure costs twice as much in one county as in a nearby county; and determine where private plans are the dominant spenders, and may have more negotiating clout, and where private plans are minor players and may have less ability to bargain for lower prices.

The data: The federal government now requires health insurers and some health care providers to post extensive cost data.

Turquoise, the Health Care Cost Institute and FAIR Health are examples of organizations that have created health care cost studies and tools based on the public data feeds, commercial claim databases or other sources.

Related: Cost of giving birth? $17,990 in 2023, FAIR Health finds

Dieleman team says its paper draws on much bigger, broader, more detailed streams of data, including 40 billion insurance claims, with separate spending figures for Medicare plans, Medicaid plans and patients' own pockets as well as private payers.

The spreadsheets that come with the paper break out spending totals, by year, location, type of provider and payer type, for everything from acute glomerulonephritis to well-person care.