Test benefits don't always justify the cost

MEDICAL MATTERS:Intervention can sometimes cause harm

HAVE YOU ever felt that a doctor is possibly carrying out an unnecessary test on you? Perhaps you have been referred from a local hospital to a specialist centre and yet it seems that some test results haven’t made it. So here you go having the same blood tests as last week repeated or even an MRI scan reordered despite the original being just days old.

Clearly such retesting is wasting precious resources that would be better deployed for another person’s benefit. A more efficient health service with joined-up IT systems would help cure much of this wasteful behaviour.

However, there is another, less obvious, form of over-testing at play. Many screening and diagnostic tests may offer little benefit and sometimes cause harm. With health costs rising unsustainably, and the infamous troika looking for every possible saving in public spending, reducing costs while maintaining high-quality healthcare is a priority.

The American College of Physicians (ACP) recently launched an initiative which we could usefully replicate here.

It has identified some 37 common clinical situations in which tests are often used in ways that provide little or no benefit to patients. In doing so it wants to stimulate more discussion among patients and doctors on how to achieve what it calls “high-value, cost-conscious healthcare”.

What is high-value care? According to the ACP, it occurs when the health benefits of an intervention justify its harms and costs. An expensive test that alters the care of a patient in a way that produces a more positive outcome is of greater value than a cheap one that does not.

For example, a patient with documented pneumonia who has responded well to intravenous antibiotics is unlikely to benefit from repeated chest X-rays before being discharged home to continue treatment with oral antibiotics.

Some of the other scenarios suggested by the ACP include performing invasive testing of the coronary arteries in patients with chronic stable angina with well-controlled symptoms on medical therapy; carrying out annual cholesterol screening for patients not receiving a lipid-lowering drug or on a prescribed diet; and screening for prostate cancer in men older than 75 or with a life expectancy of less than 10 years.

Probably one of the most wasteful tests of all is sending a patient with non-specific low back pain for X-ray or an MRI scan in the absence of any worrying symptoms or signs. And for the person who is lined up for elective surgery but is otherwise healthy, is there really a need for routine pre-operative blood tests?

A good rule of thumb for both doctors and patients is that when the pre-test probability of disease is low, the likelihood of a false positive test result is higher than the likelihood of a true positive result. For example, a positive cardiac exercise stress test result in an asymptomatic 45-year-old man is more likely to be a false-positive result than is a positive result in a 55-year-old man with chest pain on exertion that settles with rest.

False-positive results are of concern because they often lead to further testing, which may be expensive and potentially harmful. They may also create anxiety and may lead to inappropriate treatment. And we sometimes forget that the true cost of a test includes not only the cost of the test itself but also the costs incurred further downstream as a result of performing the first unhelpful test.

Here are some useful questions to ask yourself and your doctor when medical tests are proposed:

• Have I had this test previously? If so, is the result of a repeated test likely to be substantively different from the last result?
• Will the test result change my care?
• What are the likelihood and potential adverse consequences of a false positive result?
• Am I in any short-term danger if this test is not carried out?
• Am I pushing to have this test done for reassurance?
• If so, are there other ways I can be reassured?