Journalists Win Unprecedented Access to Medicare Claims Data
In fall 2022, a Wall Street Journal investigative team took an unusual step. They asked the federal Centers for Medicare and Medicaid Services (CMS) to treat them as researchers. Their goal was to access the agency’s massive repository of Medicare data for a series on suspected overbilling in Medicare Advantage.
“They agreed and gave us a data-use agreement that allowed us to access 100% of what’s called person-level Medicare and Medicaid claims over a 12-year period,” said Christopher Weaver, the Journal’s investigative reporter. That meant every prescription filled, every doctor visit, and every hospitalization — recorded in minute detail.
The Massive Medicare Data Access
Billions of Records, Billions of Dollars
The scale of the data was staggering. Weaver compared it to “being the dog that caught up with the car,” as the team suddenly had to learn to work with billions upon billions of medical records.
The stakes were equally large. Medicare cost the federal government $1.12 trillion in 2024. Of that total, private insurers operating Medicare Advantage plans were expected to receive between $500 billion and $600 billion, according to CMS data. Meanwhile, total Medicare enrollment stands at 69.7 million seniors aged 65 and older. Notably, 51.1% of those seniors are enrolled in Medicare Advantage or similar private health plans.
CMS delivered the data in August 2023, under the Biden administration. Weaver acknowledged uncertainty about whether a similar request would succeed under the current administration. “I don’t know if we would be able to navigate that process now or not,” he said.
The Investigative Team Behind the Series
The reporting team combined specialized skills. Alongside Weaver were Anna Wilde Mathews (health insurance), Mark Maremont (senior investigative editor), Andrew Mollica (graphics), and Tom McGinty (databases and public records). Together, they analyzed roughly 40,000 lines of code and conducted hundreds of interviews.
What the Medicare Records Revealed
Insurers Added Diagnoses Patients Never Had
Once the team understood the data, their findings were alarming. Major Medicare Advantage insurers — including UnitedHealth Group and CVS Health — used questionable billing practices that cost taxpayers billions and endangered vulnerable patients.
As of 2025, UnitedHealth Group leads Medicare Advantage enrollment with 9.9 million members, representing 29% of all seniors in MA plans. Humana follows with 5.7 million members (17%), and CVS Health holds 4.1 million (12%), according to KFF.
A striking example emerged from Boston. A UnitedHealth Group Medicare Advantage member received a $50 gift card during a nurse visit. The nurse examined her, asked questions, and then diagnosed her with diabetic cataracts. Each added diagnosis increases insurer payments from Medicare. In this case, the insurer could collect about $2,700 more annually. However, the patient’s own doctor confirmed she did not have diabetes at all.
Questionable Diagnoses at Scale
Hundreds of Thousands of Suspicious Medical Records
The team’s analysis of Medicare records from 2018 to 2021 uncovered hundreds of thousands of questionable diagnoses. These diagnoses generated extra payments, even though some charges were, in the team’s words, “outright wrong.”
Some diagnoses involved potentially deadly conditions. Insurers flagged patients for serious illnesses like AIDS — yet those patients received no follow-up treatment. In many cases, neither patients nor their doctors knew about the added diagnoses.
Weaver described the problem as a mix of elements. “It was a mix of fraud and a kind of gamesmanship and maybe some laxity on the part of public officials who set up the system,” he said. Furthermore, many diagnoses may have appeared anatomically plausible but were never intended for treatment.
KFF estimated that the federal government paid about 20% more to Medicare Advantage insurers than it would have for equivalent care in traditional Medicare — amounting to $84 billion in additional spending.
Awards and Senate Recognition
Pulitzer Finalist and Senate-Cited Investigation
The series earned significant recognition. The team became a Pulitzer Prize finalist in 2025 for investigative reporting. The Pulitzer committee praised the work as “a comprehensive series showing how health insurers gamed the MA program to collect billions for nonexistent ailments while shunting expensive cases onto the public.”
In addition, the series won awards from Investigative Reporters & Editors and the New York Press Club. It was also a finalist for the Goldsmith Award from Harvard’s Shorenstein Center.
Beyond journalism honors, the U.S. Senate Committee on the Judiciary cited the Journal and STAT News more than two dozen times in a January 2025 report: “How UnitedHealth Group Puts the Risk in Medicare Advantage Risk Adjustment.” STAT News had simultaneously investigated how UnitedHealth Group used acquired physician groups to boost its own profits.
Lessons for Investigative Journalists
Start Small, Build Skills, Then Scale Up
Weaver offered candid advice for reporters considering similar investigations. Without access to CMS data, he argued, such reporting becomes nearly impossible. “Essentially, it’s a business about manipulating data. How do you expose that without being able to look at the numbers?” he asked.
High barriers to entry exist for this type of work. One team member had to learn SAS programming from scratch. Patients also had to locate their own medical records and sign legal releases before sharing them with reporters.
Nevertheless, Weaver encouraged journalists to pursue this path — starting modestly. “For journalists venturing into this type of reporting that combines health services research and claims analysis, I’d suggest starting smaller than we did,” he advised. “Maybe start by looking at hospital or nursing home claims. Then you can build up the competencies you’ll need.”
