This story was co-published with the New York Times' The Upshot.

For more than five decades, the blood thinner Coumadin was the only option for millions of patients at risk for life-threatening blood clots. But now, a furious battle is underway among the makers of three newer competitors for the prescription pads of doctors across the country.

How Much Industry Money Goes to Doctors, Teaching Hospitals

Beginning in 2014, the federal government mandated that pharmaceutical and medical device manufacturers publicly report their payments to doctors and teaching hospitals. Use this tool to search for a company, drug or device — and compare it to another. Explore the app

The manufacturers of these drugs — Pradaxa, Xarelto and Eliquis — have been wooing physicians in part by paying for meals, promotional speeches, consulting gigs and educational gifts. In the last five months of 2013, the companies spent nearly $19.4 million on doctors and teaching hospitals, according to ProPublica's analysis of federal data released last fall.

The information, from a database known as Open Payments, gives the first comprehensive look at how much money drug and device companies have spent working with doctors. What it shows is that the drugs most aggressively promoted to doctors typically aren't cures or even big medical breakthroughs. Some are top sellers, but most are not.

Instead, they are newer drugs that manufacturers hope will gain a foothold, sometimes after failing to meet Wall Street's early expectations.

"They may have some unique niche in the market, but they are fairly redundant with other therapies that are already available," said Dr. Joseph Ross, an associate professor of medicine and public health at Yale University School of Medicine. "Many of these, you could call me-too drugs."

In almost all cases, older, cheaper products are available to treat the same conditions. Companies typically try to differentiate the new drugs by claiming they are easier to use; carry fewer side effects; work faster than competitors; or have medical advantages.

The makers of Pradaxa, Xarelto and Eliquis, for example, say their drugs are at least as effective as Coumadin for certain conditions but do not require routine blood tests or limitations on what patients can eat. (Patients taking Coumadin, also known as warfarin, shouldn't eat grapefruit or cranberries and have to limit green leafy vegetables in their diet.)

Officials at the Centers for Medicare and Medicaid Services, which administers Open Payments, and the Pharmaceutical Research and Manufacturers of America, the drug industry trade group, said they had not analyzed the data in order to rank spending by drug.

When told of ProPublica's analysis, John Murphy, PhRMA's assistant general counsel, said drug makers' spending should be seen not only as a marketing strategy, but also as a way of ensuring the best treatment options for patients. "On paper, a drug may not look like it is monumentally better than another drug, but to an individual patient, it might be," Mr. Murphy said.

According to ProPublica's analysis, Victoza, a diabetes medication made by Novo Nordisk, was the drug associated with the most payments to doctors, by dollar amount. The company spent more than $9 million on physician interactions related to Victoza in the last five months of 2013, excluding research payments and royalties, which relate more to drug development than marketing. (ProPublica created a tool that lets you look up any drug, device or company and compare it with any other.)

Victoza, through a once-a-day injection, helps lower blood sugar among diabetics, but researchers and advocacy groups have said drugs of its class carry an increased risk of thyroid cancer and pancreatitis. Dr. Todd Hobbs, chief medical officer of Novo Nordisk in North America, said the company's spending reflected Victoza's newness and the need to address such safety concerns.

"We just received a huge amount of interest and questions and need for education," Hobbs said, referring to inquiries by health care professionals, particularly primary care doctors. "You see the fruits of that in this report."

Eliquis, the anticoagulant jointly marketed by Bristol-Myers Squibb and Pfizer, ranked second in its link to spending on physicians, with nearly $8 million, our analysis showed. In a statement, the companies said their spending helps ensure physicians understand the appropriate use of Eliquis. Because the drug is prescribed by physicians in different specialties, the statement said, "it is critical to have a speaker program that adequately provides robust education to these physicians."

The drug associated with the third-most payments to doctors was Brilinta, a different type of blood thinner made by AstraZeneca that vies for sales with Plavix, which is now available generically. In an email, AstraZeneca said it had identified Brilinta as one of its "key platforms for growth" and increased speaker and research spending on it. "Physicians are also indispensable partners in our efforts to bring new medicines to patients," the company said.

ProPublica has tracked drug companies' payments to doctors since 2009 through a searchable database called Dollars for Docs. But this covers only 17 companies, most of which have been compelled to release this information under legal settlements with the government. It has no information from medical device makers.

The list of most promoted drugs featured many recent arrivals: 14 of the top 20 were approved by the Food and Drug Administration since 2010. Some treat similar conditions, including diabetes, schizophrenia and chronic obstructive pulmonary disease, so the competition among them is fierce. "They're fighting over the same doctors, I guarantee you," said Rhonda Greenapple Simoff, founder of a consulting firm that advises pharmaceutical companies in Bernardsville, N.J.

Largely absent from the top of the list were drugs that cure disease, such as a new class of hepatitis C treatments, or those that significantly extend life, particularly for cancer patients. If a drug is either the first to treat a disease or is much better than existing drugs, said Dr. Sidney Wolfe, the founder and now senior adviser to Public Citizen's Health Research Group, "they 'sell themselves' on the merits of their unique benefits."

According to ProPublica's analysis, a few of the most heavily promoted drugs, including Samsca, which treats low sodium levels in the blood, have serious side effects that came to light after their approval by the federal government. The manufacturers of several others, including Copaxone, Latuda, Xarelto, Daliresp and Humira, have been faulted by the F.D.A. for improper promotion.

Subsys, approved in 2012 to treat cancer pain, ranked 23rd in spending on doctors. It's often prescribed for off-label, or unapproved, uses; in November, The New York Times reported that some of the doctors paid the most to promote the drug had disciplinary or legal troubles. In a statement to The Times, Insys Therapeutics, the drug's maker, said its marketing of Subsys was appropriate.

The medical device associated with the most payments to doctors was Intuitive Surgical's da Vinci surgical robot system, which the company has marketed as an effective, less invasive option for an array of procedures. Critics have complained that the device is needlessly expensive and overused, and say it has been linked to patient complications and deaths.

Intuitive spent nearly $12.8 million on physician interactions to promote the robot in the last five months of 2013, not including royalties and research. The spokeswoman Paige Bischoff said in an email that about half of the company's outlays for education and training were "pass through" spending: Surgeons or hospitals paid the company for services, and the company, in turn, paid doctors to provide them.

Dr. Robert Takla, an emergency room physician in the Detroit area, earned about $75,000 in the last five months of 2013 by delivering promotional talks about several of the most heavily marketed anticoagulants and blood thinners, particularly Brilinta, according to Open Payments.

He said he enjoys speaking on behalf of companies and thinks he offers a different perspective than cardiologists and internists — the usual prescribers of the drugs — because he treats complications of blood clots in the emergency room.

Dr. Takla said he reviews clinical studies before deciding to speak for a drug and turns companies down when he isn't impressed. He said he no longer spoke on behalf of Pradaxa because of what he characterized as public backlash against it, driven by a spate of lawsuits against its manufacturer, Boehringer-Ingelheim. (The company agreed to pay $650 million last year to settle the suits.) He accepts fees to speak about Xarelto, a drug he has taken himself for a deep vein thrombosis.

"It's a very fertile and very robust marketplace right now," he said of the anticoagulants.

News applications developer Mike Tigas contributed to this report.

Methodology: How we calculated company payments to doctors