The Commonwealth Fund released Monday a bag-of-tricks report claiming that America has the worst healthcare system in the developed world and Great Britain the best. But actual data show the opposite. For example, a woman diagnosed with breast cancer in the United States has an 89% chance of surviving it, higher than anywhere in Europe.

The Commonwealth’s dubious conclusion ordinarily wouldn’t deserve comment. But Commonwealth’s bad science is partly to blame for our current predicament, struggling with Obamacare. Earlier versions of the report issued in 2004, 2006, and 2007, bamboozled some members of Congress into believing that health care is better in countries where government calls the shots.

For example, in October, 2009, Senator Kent Conrad pointed to a large blue chart during a Finance Committee meeting showing the United States in last place in health performance. “All of these countries have much lower costs than we do,” said the North Dakota Democrat, “and they have higher quality outcomes than ours.” Conrad had been duped by an earlier Commonwealth report.

Now the left-wing group is at it again, and the main stream press is busy parroting its claims that socialized medicine is tops.

Commonwealth gives heavy weight to “equity,” meaning equal access to care. So countries with government run systems automatically come out on top. The ranking totally ignores a measure most men want to see: survival rates for prostate cancer. The U.S. is stunningly effective in treating this disease. An American diagnosed with it has a 99.3% chance of survival.It’s not a death sentence here, but in Great Britain only 70% survive, in Germany only 82%, and in Denmark a shockingly low 48%.

In the Commonwealth ranking, countries get top grades if doctors say “it’s easy to print out lists of patients by diagnosis.” Here’s another one. Countries rank highest when patients are “routinely sent computerized reminder notices for preventive or follow-up care.” The U.S. lost points because it is more common here to telephone patients than e-mail them. Never mind that American women are most likely to actually get mammograms or other preventive care.

The report’s biggest trick is penalizing the U.S. for having the highest number of deaths due to preventable diseases, meaning diseases curable if treated soon enough. The report confuses incidence and success treating disease. The U.S. has a high incidence of cardiovascular disease, considered preventable, because for 50 years Americans were the heaviest smokers and now are among the most obese. Bad behavior, not bad medicine is to blame. The U.S. healthcare system treats these diseases very effectively.

As the National Bureau of Economic Research cautioned about the Commonwealth’s preventable deaths measurement: “It seems inaccurate to attribute. . . high death rates from these causes to a poorly performing medical system.”

Shorter life expectancy in the U.S.? But don’t be fooled. The causes of reduced U.S. life expectancy are our higher rates of auto fatalities and violent crime, plus half a century of excessive smoking – not bad medicine.

As the NBER concludes, “the low longevity ranking of the United States is not likely to be the result of medical failures.”

Biased science convinced at least a few lawmakers to vote for Obamacare. Even as the health law’s costs soar and dysfunctions multiply, its defenders still tout socialized medicine and bend the facts to make it look successful. .