Does research back up the frustrations Americans feel toward the health care industry?

The fatal shooting of UnitedHealthcare CEO Brian Thompson, along with the alleged grievances of the suspect charged in his murder, have thrust the country's health care industry into the spotlight.

At the time of his arrest, suspect Luigi Mangione reportedly had with him writings that criticize companies in the U.S. health care industry for being the most expensive in the world, according to law enforcement.

The writer also allegedly suggests that the U.S. continuously ranks lower than other developed nations in life expectancy, reportedly stating: "They continue to abuse our country for immense profit because the American public has allowed them to get away with it."

The events surrounding Thompson's murder have spurred a national conversation about the rising cost and, for some, inaccessibility of health care, which has been a longstanding concern for Americans.

The U.S. on average spends twice as much or more per person on health care per capita than some comparable high-income countries, according to KFF, a nonprofit health policy research, polling and news organization.

Health costs have generally grown faster than inflation, according to researchers, contributing to the struggles faced by many Americans to afford health care and drugs, even with insurance.

One 2019 study published in Health Affairs found that despite spending more on average for health care, Americans aren't getting more or better care than residents in other developed countries.

About half of U.S. adults said it is hard to afford health care costs, according to a KFF study – forcing some to skip or postpone needed care.

One in four adults said that they have skipped or held off on health care they needed because of the price tag, KFF reported; of the uninsured adults surveyed, 61% said they have gone without needed care because of the cost.

A KFF study also found that about 4 in 10 U.S. adults reported having medical or dental debt, which translates to an estimated 100 million adults. About 1 in 5 said they might never be able to pay off their debt, and about 1 in 7 say they have been denied access "to a hospital, doctor, or other provider" because of those unpaid bills.

Kaye Pestaina, the vice president at KFF and director of the Patient and Consumer Protections program, told ABC News there's a laundry list of frustrations Americans face in the country's health care system.

"Folks are happy when they do have coverage, and then the expectation is, when they need it, it'll be there for them," she said, while explaining that it isn't always the case.

She lists examples like when patients are told their prescribed care isn't medically necessary or are denied coverage, when there are more out-of-pocket costs than expected or when care they need isn't covered by insurance.

An analysis of HealthCare.gov data found that roughly 17% of in-network claims were denied by insurers in 2021.

Or, Pestaina adds, some patients are stuck with extremely high deductibles, and they may not be able to use enough for any care to be covered by insurance.

"The system is so complicated for most people, we don't have the time or the information that we need to get our problems addressed," said Pestaina.

U.S. adults owe at least $220 billion in medical debt, according to one analysis of Survey of Income and Program Participation data.

Meanwhile, insurance companies and pharmaceutical companies have racked up billions in profits annually.

Pestaina believes the for-profit health care system has contributed to increasing prices.

Harvard professor David Cutler points to several key contributors to higher costs – including the administrative costs and price hikes of drugs and hospital care.

Harvard Medical School researchers found that administrative costs alone account for up to 25% of health care costs: "Running the whole system is more expensive in the U.S. than elsewhere," Cutler said.

Cutler has pointed out that the ability for pharmaceutical companies to price their medications "without constraint is a recipe for premature death" -- with prices being higher in American than other countries.

The U.S. Governmental Accountability Office found in 2020 that the estimated prices for 20 selected brand prescription drugs were more than 2 to 4 times higher than prices in other countries such as Australia, Canada and France.

Researchers say Americans are right to feel frustrated about all this when it comes to health care.

"It's not just: Push a button and the thing goes away. But it's not undoable either, and we shouldn't be okay with doing nothing," said Cutler.