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[UPDATED at 4:30 p.m. ET]

When biopharma company Amarin teased its latest clinical trial results this fall, it stirred both buzz and controversy in the medical community by suggesting its drug, Vascepa, could transform heart disease prevention. The company’s stock skyrocketed.

But this month at the American Heart Association’s scientific sessions, an annual who’s who of cardiology, the company unveiled the complete study findings, also published in the New England Journal of Medicine. The bottom line: Vascepa, a prescription fish oil derivative, reduced the likelihood of cardiovascular death, stroke and heart attack, afflictions that affect tens of millions of Americans, by about 26 percent.

“The result is spectacular,” said Dr. Ethan Weiss, a cardiologist at the University of California-San Francisco, who was not involved in the trial. But he — like many other doctors — still had qualms.

Even as Amarin and some cardiologists use superlatives to tout the results of the Vascepa trial, questions abound — about the study’s design and whether the benefits of Vascepa justify its price, considering how its ingredients compare to over-the-counter fish oil supplements. According to Red Book, a pharmaceutical trade publication, a month’s supply of Vascepa retails for about $280.

ConsumerLab.com, a privately held company that tests dietary supplements, recently conducted its biennial review of fish oil products. It analyzed 28, including ones marketed for heart health, for pregnant women, for children and even for pets. It found serious issues with four of those, including inaccurate labeling and failure to accurately identify ingredients — namely the pills’ enteric coating.

And of those 28, ConsumerLab did find one — GNC Triple Strength EPA 1000 — that it says has a similar chemical breakdown to Vascepa but retails at a fraction of the price. A bottle of 45 pills costs about $30, and users would take four pills a day.

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Vascepa is already approved as a preventive for people with extremely high triglyceride levels — 500 milligrams per deciliter or higher. The goal of the study was to demonstrate that it could be healthful for the much larger group of people at increased risk of heart disease. People in this broader population who were included in the trial were already taking a cholesterol-lowering statin.

After five years, the patients taking Vascepa in addition to a statin saw reduced odds of major cardiovascular problems, including death, over those who took a placebo.

But how that applies in the doctor’s office or at home remains controversial. “We have this trial, [but] what does this mean to our patients?” asked Dr. Sanket Dhruva, another UCSF cardiologist, who, like Weiss, was unaffiliated with the study. “It’s tricky.”

For starters, the trial focused on patients who had high triglyceride levels, a history of heart disease or another elevated risk, and were already taking statins. That means the benefits are focused on a specific population, said Dr. Steven Woloshin, who co-directs the Dartmouth Institute’s Center for Medicine and Media and studies effective scientific communication.

And the study’s underlying method — specifically, comparing patients on Vascepa to those taking a mineral oil pill — has fueled questions. Placebos are supposed to act neutrally, so that researchers can compare the drug to an unchanged environment. Substituting mineral oil may establish a flawed baseline. Some evidence suggests it increases the risk of heart problems. That would mean the Vascepa results looked rosier because they were measured against a particularly favorable benchmark.

Dr. Steven Nissen, chief of cardiology at the Cleveland Clinic, agreed that the mineral oil effect called into question the extent to which Vascepa prevented heart attacks.

Amarin and its researchers say any such effect is small enough that it shouldn’t undercut the overall results. Others were less sure. “It makes interpreting this whole thing messier than anyone would want it to be,” Weiss said.

To make medical decision-making even more complicated, a separate study presented at the same November meeting found that healthy older people who take over-the-counter fish oil supplements — specifically omega-3 fatty acids — didn’t reduce heart disease risk. Conventional wisdom has long suggested that fish oil, ingested through food or pills, could bolster heart health. Many doctors recommend it as part of a healthy diet.

All this creates a conundrum for consumers concerned about their heart health — especially those trying to spend limited dollars wisely, suggested Dr. Tod Cooperman, president of ConsumerLab.

There is no evidence that fish oil is harmful, and the heart association says supplements could reduce the risk of death if someone has recently had a heart attack. (It’s less enthusiastic, though, about the pill as an across-the-board preventive for cardiovascular disease.)

So, is it worth shelling out money for Vascepa versus buying a supplement at the corner store?

“If their doctor thinks they could benefit from Vascepa — but affordability is an issue — definitely consider a [fish oil] product that has been tested,” suggested Erin Fox, a pharmacist and drug expert at the University of Utah.

“I would never recommend a dietary supplement to a patient, and I would never take one myself,” Nissen said. “There have been numerous issues with products like these. As much as I’d love to believe that some over-the-counter product would work, and save the public tons of money, it’s just not a recommended approach.”

That’s in part because the over-the-counter variant does not require Food and Drug Administration approval before hitting the market, which means less guarantee of purity and precise dosing.

Nissen, who is launching his own study of fish oil-derived drugs, said that when it comes to Vascepa, both doctors and patients need to “take a deep breath” and see what the FDA makes of Amarin’s results, before even thinking about what kind of value it offers.

“It comes down to our conversations with our patients, in the clinic or at the bedside, about what is realistic given these very high costs of the drugs,” Dhruva said.

Senior correspondent Liz Szabo contributed to this report.

KHN’s coverage of prescription drug development, costs and pricing is supported in part by the Laura and John Arnold Foundation.