Merck & Co. Inc. has provided new data to U.S. regulators showing that all patients who took the arthritis medicine Vioxx were at increased risk of heart attacks, strokes and other complications, National Public Radio reported on Wednesday.

Merck, which disputed the report, withdrew Vioxx from the market in September 2004 after a study showed the drug doubled the chances of heart attacks and strokes in patients who took it for at least 18 months.

A 107-page report provided to the Food and Drug Administration by Merck last week included data from a four-year study suggesting the risk started much earlier, NPR said.

“Experts who have reviewed (the data) for NPR say it shows that patients were at higher risk of heart problems and strokes almost as soon as they started taking Vioxx,” NPR said.

Merck, which is facing thousands of lawsuits alleging harm from Vioxx, disagreed with NPR’s description of the report.

The company said the data came from a study called Approve that prompted the decision to withdraw Vioxx from the market.

The new data from Approve “do not establish that the risk for Vioxx starts earlier than had previously been reported,” Merck said in a statement.

Merck announced last week that new findings from the Approve study showed patients who stopped taking Vioxx had no greater risk of heart attacks and strokes in the year following therapy than others who took a placebo. One leading cardiologist has questioned the company’s analysis.

FDA spokeswoman Laura Alvey said the agency was reviewing all the data Merck had submitted.

A study published online earlier this month by the Canadian Medical Association Journal said Vioxx may elevate heart-related risks early in treatment.

Researchers at McGill University Health Center said their review of three years of data on Vioxx users found one-quarter of patients who suffered a heart attack did so within the first two weeks of taking their first Vioxx prescription.

That study showed the cardiovascular risk actually decreased with longer duration of use.

A Texas jury found last month the painkiller caused the death of a 71-year-old man who had taken the drug for less than a month, and awarded his family damages of $32 million.