It is no longer news that Americans, and older Americans in particular, get more routine screening tests than they need, more than are useful. Prostate tests for men over 75, annual Pap smears for women over 65 and colonoscopies for anyone over 75 -- all are overused, large-scale studies have shown.

 

Now it appears that many older patients are also subjected to too-frequent use of the other kind of testing, diagnostic tests.

 

The difference, in brief: Screening tests are performed on people who are asymptomatic, who aren't complaining of a health problem, as a way to detect incipient disease. We have heard for years that it is best to "catch it early" -- "it" frequently being cancer -- and though that turns out to be only sometimes true, we and our doctors often ignore medical guidelines and ongoing campaigns to limit and target screening tests.

 

Diagnostic tests, on the other hand, are meant to help doctors evaluate some symptom or problem. "You're trying to figure out what's wrong," explained Gilbert Welch, a veteran researcher at the Dartmouth Institute for Health Policy and Clinical Practice.

 

For these tests, medical groups and task forces offer many fewer guidelines on who should get them and how often -- there is not much evidence to go on -- but there is general agreement that they are not intended for routine surveillance.

 

But a study using a random 5 percent sample of Medicare

beneficiaries -- nearly 750,000 of them -- suggests that often, that is what's happening.

 

"It begins to look like some of these tests are being routinely repeated, and it's worrisome," said Dr. Welch, lead author of the study just published in The Archives of Internal Medicine. "Some physicians are just doing them every year."

 

He is talking about tests like echocardiography, or a sonogram of the heart. More than a quarter of the sample (28.5 percent) underwent this test between 2004 and 2006, and more than half of those patients (55 percent) had a repeat echocardiogram within three years, most commonly within a year of the first.

 

Other common tests were frequently repeated as well. Of patients who underwent an imaging stress test, using a treadmill or stationary bike (or receiving a drug) to make the heart work harder, nearly 44 percent had a repeat test within three years. So did about half of those undergoing pulmonary function tests and chest tomography, a CAT scan of the chest.

 

Cystoscopy (a procedure in which a viewing tube is inserted into the bladder) was repeated for about 41 percent of the patients, and endoscopy (a swallowed tube enters the esophagus and stomach) for more than a third.

 

Is this too much testing? Without evidence of how much it harms or helps patients, it is hard to say -- but the researchers were startled by the extent of repetition. "It's inconceivable that it's all important," Dr. Welch said. "Unfortunately, it looks like it's important for doctors."

 

The evidence for that? The study revealed big geographic differences in diagnostic testing. Looking at the country's 50 largest metropolitan areas, it found that nearly half the sample's patients in Miami had an echocardiogram between 2004 and 2006, and two thirds of them had another echocardiogram within three years -- the highest rate in the nation.

 

In fact, for the six tests the study included, five were performed and repeated most often in Florida cities: Miami, Jacksonville and Orlando. "They're heavily populated by physicians and they have a long history of being at the top of the list" of areas that do a lot of medical procedures and hospitalizations, Dr. Welch said.

 

But in Portland, Ore., where "the physician culture is very different," only 17.5 percent of patients had an echocardiogram. The places most prone to testing were also the places with high rates of repeat testing. Portland, San Francisco and Sacramento had the lowest rates.

 

We often don't think of tests as having a downside, but they do. "This is the way whole cascades can start that are hard to stop," Dr. Welch said. "The more we subject ourselves, the more likely some abnormality shows up that may require more testing, some of which has unwanted consequences."

 

Properly used, of course, diagnostic tests can provide crucial information for sick people. "But used without a good indication, they can stir up a hornet's nest," he said. And of course they cost Medicare a bundle.

An accompanying commentary, sounding distinctly exasperated, pointed out that efforts to restrain overtesting and overtreatment have continued for decades. The commentary called it "discouraging to contemplate fresh evidence by Welch et al of our failure to curb waste of health care resources."

 

It is hard for laypeople to know when tests make sense, but clearly we need to keep track of those we and our family members have. That way, if the cardiologist suggests another echocardiogram, we can at least ask a few pointed questions: "My father just had one six months ago. Is it necessary to have another so soon? What information do you hope to gain that you didn't have last time? Will the results change the way we manage his condition?"

 

Questions are always a good idea. Especially in Florida.