No one knows how often health insurers deny claims. Here’s why

UnitedHealthcare (UNH-0.73%) is facing increasing scrutiny for its allegedly high claim denial rate. However, since insurers try to keep these numbers hidden, the true extent of its denials remains uncertain, especially when it comes to private plans.

The heightened scrutiny comes as the company’s CEO Brian Thompson was fatally shot in New York City on Wednesday morning, just hours before he was set to speak at the healthcare firm’s annual investor day.

Multiple outlets reported on Thursday that shell casings from the shooting had the words “deny,” “defend,” and “depose” written on them. Some have speculated that these words refer to terms industry critics use to describe tactics that insurers employ to deny claims.

At the same time, posts on social media have been claiming that UnitedHealthcare’s claim denial rate is the highest in the industry at 32%. This figure comes from the personal finance website Value Penguin, which said it calculated that rate from available in-network data from plans sold on the marketplace.

UnitedHealthcare did not immediately respond to a request for comment from Quartz. UnitedHealthcare is a division of UnitedHealth Group and the largest private health insurer in the U.S. with a market cap north of $500 billion. Its biggest business, UnitedHealthcare Employer and Individual, serves more than 29 million Americans through health benefit plans.

Although the Affordable Care Act permits regulators to require insurers to share information on claim denials, the federal government has so far not collected much of this data and has shared even less with the public, according to a 2023 report from ProPublica.

Still, some recent reports show that denials have been on the rise.

In October, a report from the U.S. Senate Permanent Subcommittee on Investigations showed that the nation’s insurers have been using AI-powered tools to deny some claims from holders of Medicare Advantage plans.

The report found that UnitedHealthcare’s denial rate for post-acute care — health care needed to transition people out of hospitals and back into their homes — for people on Medicare Advantage plans rose to 22.7% in 2022, from 10.9% in 2020.

In August, a report from the health policy research non-profit KFF found that all Medical Advantage insurers fully or partially denied 7.4% of prior authorization requests — requests for coverage of specific medical services — in 2022, up from 5.4% in 2019.