It’s shocking to learn that errors in medical care cause more U.S. deaths than anything short of heart disease and cancer. But it’s the good kind of shock.

Medical errors have almost certainly been killing Americans at a high rate for some time. Because of shortcomings in how those deaths are reported, however, they’ve never been listed among the top causes of deaths, and thus are not seen as a serious threat to mortality.

That should change. Medical errors are highly preventable, and improvements to the way they are recorded and investigated would lower their frequency, and save lives.

A lot of lives, actually.

A study from a professor of surgery at Johns Hopkins University School of Medicine, published this week in the BMJ, estimates that medical errors kill more than 250,000 Americans a year, more than COPD, suicide and motor vehicle accidents. That’s 9.5 percent of all deaths, nearly 700 day.

The numbers may sound high, but they are supported by prior research. A 2004 Medicare report estimated that 575,000 people died as a result of medical error from 2000-02, an average of more than 190,000 a year. The U.S. Department of Health and Human Services reported that 180,000 Medicare beneficiaries alone died from medical error in 2008.

And in 1999, an Institute of Medicine report estimated annual deaths resulting from medical error at 98,000, which many researchers said at the time was likely a significant underestimate.

The 1999 report caused a stir, but no real action, among medical professionals and policymakers. Sixteen years later, not much has improved.

Secrecy is a big part of the reason why. When doctors diagnose the wrong problem, prescribe the wrong treatment, or err in following through on the treatment plan — or when a care provider makes any of the million human mistakes that can result in death in a clinical setting — hospitals and other health-care facilities are not eager to talk about it.

Their silence is protected, too, by the Centers for Disease Control and Prevention, which doesn’t require the reporting of medical errors on death certificates. As a result, medical errors are not listed among other significant causes of death, and are kept off the annual lists that let people know, for example, just how big a problem respiratory disease is, and what kind of response it warrants.

That’s a shame. Deaths caused by “communication breakdowns, diagnostic errors, poor judgment, and inadequate skill,” as the BMJ study describes medical error, could benefit from more sunlight.

Improved data collection and dissemination — along with more thorough, independent investigations of errors — would allow all hospitals and health-care providers to learn from the mistakes of others, leading to the creation of better systems and protocols.

Human error can never be entirely removed from medicine, but it can be recognized and mitigated. A patient’s main concern should be the severity of his illness, not the adequacy of his treatment.