NEW YORK (Reuters) - Jen Watson, a 41-year-old mother in Federal Way, Washington, has worked for years with her doctor to find the right medications to deal with her multiple chronic illnesses, which include epilepsy and fibromyalgia.

Her doctor had found some medications that could reduce Watson's nerve pain, but Watson says her UnitedHealthcare Medicaid plan refused to cover the drugs. And because of her pain, it has been hard for Watson to find work.

"I've been struggling to find work in part because I can't stand for more than 15 minutes and end up in serious pain very quickly because my symptoms aren't well managed," Watson told Reuters.

The killing last week of a powerful health insurance executive has ignited an outpouring of anger from Americans struggling to receive and pay for medical care.

Police are still hunting for the man suspected of killing Brian Thompson, chief executive of UnitedHealthcare, and have not determined a motive. But the attack called fresh attention to deepening frustrations over health coverage.

Recent data show that patients are now even more likely to have their claims denied, pay more for premiums and medical visits, and face unexpected costs for care they thought was covered by their health plan. Rising costs are attributed in part to consolidation of doctors' practices, hospitals and insurers.

UnitedHealthcare, part of UnitedHealth Group ( UNH ), is the largest manager of health benefits, followed by Cigna ( CI ) and CVS Health ( CVS ).

"It's a very shocking event. But it's also an opportunity for people to vent about issues that have been of great concern to many people," said Tahneer Oksman, a professor at Marymount Manhattan College's communications department in New York.

Americans pay more for health care than any other country and over the past five years, spending on insurance premiums, out-of-pocket co-payments, pharmaceuticals and hospital services has increased, government data shows.

Shares of UnitedHealth ( UNH ) have nearly doubled over the last five years. During the week of the shooting, UnitedHealth ( UNH ) shares fell by more than 10% through Friday.

UnitedHealth ( UNH ), CVS and Cigna ( CI ) did not provide a comment for this story.

Insurance industry trade group AHIP said in an emailed statement that health plans, providers and drugmakers share responsibility to make care as affordable as possible and easier to navigate.

"Health plans are working to protect patients from the full impact of rising costs while connecting them to care that is safe, evidence-based and coordinated," the group said.

Insurers who manage health benefits and drug benefits say that they negotiate down prices of doctor visits, hospital stays and costly medications. Most plans are sponsored by employer or government clients who foot part of the bill and have a say in what gets covered.

Kevin Gade, COO at investment firm Bahl & Gaynor, which owns about 2.6% of UnitedHealth ( UNH ) shares, said companies like UnitedHealth ( UNH ) play an important role in providing critical and needed care for all patients within an inefficient U.S. healthcare system that needs to evolve.

"Unfortunately, when you're dealing with people's lives, there is a reality that there will be hiccups along the way," he said.

Justine, 51, a UnitedHealthcare customer who works at a nonprofit in New York City, was diagnosed with breast cancer in 2017 and underwent a double mastectomy in 2018. She asked that her last name be withheld for privacy reasons.

A year after surgery, she developed lymphedema, in which fluid builds up in her arm that can lead to infections and is treated by being fitted with custom-made compression sleeves.

Her employer-based insurance from UnitedHealthcare approved the sleeves, which cost $4,000 for a night sleeve, and several hundred dollars for a daytime sleeve replaced every three or four months.

But the company that made them said UnitedHealthcare failed to pay, citing various paperwork issues. "That continued for a long time," said Justine. "I kept feeling like, is this a run out the clock situation?"

The Patient Advocate Foundation, a charity that provides patient claims aid and financial assistance, has found that cases have gotten much more difficult to resolve.

In 2018, a case manager would need to initiate on average 16 phone calls or emails to resolve a claim; now, it's 27, said Caitlin Donovan, the group's spokesperson.

"The American health insurance industry is becoming more complicated to navigate, negotiate and try to appeal," Donovan said.

CLAIMS DENIALS RISE

The 2010 Affordable Care Act, commonly known as Obamacare, set new baselines for who and what insurance plans must cover. As costs have risen, insurers increasingly turned to the prior authorization process, vetting requests for medical services before agreeing to pay.

Prior authorizations were deployed 46 million times in 2022, up from 37 million in 2019, a KFF analysis of privately managed Medicare Advantage plans for people aged 65 and older or who are disabled found. CVS denied 13% of such requests while Elevance's Anthem Blue Cross Blue Shield denied 4.2%. UnitedHealthcare denied 8.7%.

Only about 10% of patients appeal these denials, and of those challenges, about one-third fail, KFF said.

In an American Medical Association 2023 survey, 94% of physicians said prior authorization delayed care, and 78% said it sometimes led to patients abandoning treatment. Nearly 1 in 4 reported it had resulted in a serious adverse event for patients and 95% reported it raised physician burnout.

Denials of health claims also increased, rising 31% in 2024 from 2022, according to a 2024 survey by credit firm Experian of 210 healthcare staff responsible for billing and reimbursement.

Patients who are denied claims appeals have few avenues of legal redress after the insurer's own process. Federal law for employer-sponsored plans limits damages to the amount of a denied claim, which means few law firms are inclined to take such cases, said Sara Haviva Mark, a lawyer who specializes in representing people whose claims are denied.

In the KFF survey, 18% said their health plans did not pay for care they thought was covered in the prior 12 months.

Rachel Benzoni, a 37-year-old doctoral student in Omaha, Nebraska, said she has watched loved ones and friends struggle to navigate the healthcare system, and has had issues receiving coverage under UnitedHealthcare for routine procedures including dental care.

"I recently paid nearly $1,000 to get periodontal work done, as United denied my entire claim," she said, adding that they did not give a reason for the denial beyond that the procedure was not covered.