Managing Healthcare Costs: exercise stress test

Today’s Managing Health Care Costs Indicator is 1.5 million

The May 4 issue of the Journal of the American Medical Association has a comprehensive literature review of the effectiveness of structured exercise in type 2 diabetics. Those who begin an structured program to exercise at least 150 minutes a week have impressive improvements in their diabetes -- improvements akin to the results of adding an additional diabetes medicine to their drug therapy.

An accompanying editorial suggests that since structured exercise is so cost effective (between $14,000 and $69, 000 per quality adjusted life year) it should be covered by health insurance.

I'm a big fan of exercise - and I do think that breaking down barriers to exercise is important. For many, the cost of joining a gym is beyond the budget. However, I couldn't disagree more with this JAMA editorial.

We have a huge affordability problem. Making health plans more “generous” through offering coverage for fitness club membership also makes them these insurance plans less affordable. This is not exactly an “unfunded mandate” in all instances under the Affordable Care Act, because the government will subsidize health insurance to the extent the cost exceeds 9.5% (or less) of income. Therefore, the government has a strong incentive to keep down the cost of health insurance.

Fortune Magazine reports that chiropractors, patient advocacy groups, and a wide range of physician specialty groups are lining up to demand that HHS include more services in its list of essential health benefits. It reports that a 10% increase in the cost of the essential benefits package would increase spending by $67 billion through 2019 and reduce the number of insured Americans by 1.5 million.

We have to figure out how to avoid medicalizing a large range of important social issues, and we must have the discipline to NOT cover services that are not medically necessary. Covering fitness club memberships through health insurance might feel good. But it would paradoxically lead to a lower rate of those with insurance for truly ‘essential’ health care coverage.

Let’s not add more mandates that would make health insurance unaffordable for more Americans.

We intuitively believe that medical diagnostic tests are more likely to banish uncertainty than they really are.

Here’s an example. Many executives have an “executive physical” that includes an exercise stress test to be sure they don’t have coronary artery disease, and many patients pay to have a CT scan to assess coronary artery calcification.

Take a 45 year old executive with a normal blood pressure and a normal cholesterol – his “pretest” probability of having a heart attack or cardiac death in the next 10 years is about 1%. Here is a link that lets you put in age, gender, blood pressure and cholesterol and calculates risk based on data from the Framingham data.

Imagine 1000 such executives, each with a 1% chance of coronary disease. That means that ten of them will have a heart attack or cardiac death in the next ten years. If they all had exercise stress tests, with a 70% sensitivity (chance a person with disease will have a positive) and a 90% specificity (chance a positive is a “true” positive” we would have 107 positives – but only 7 of them would be correct. The overwhelming majority of positive tests would be false positives. There would be almost 900 negatives, and of these only 3 would be “false” negatives.

This calculation of “posterior probability” is called Bayes Theorem

So – even with a positive test a patient has a low chance of serious cardiac event. A negative test is much more reliable. However, the executive had a 1% chance of heart disease before the test, while after the test the probability remains about 1/3 as high.

So – we have more data – but not much more information. Here is a graphic way to look at this:

Worst of all, there is not evidence that people with no symptoms benefit from invasive therapy to correct cardiac disease. Even the “lucky” executive whose hidden cardiac disease is discovered through this testing might not be so lucky either!

We desire more information – and insist on more diagnostic tests in a vain effort to banish uncertainty. Alas, tests done under the wrong circumstances don’t do much to diminish uncertainty. We want exercise stress tests, mammograms and prostate specific antigen tests, even when our risk of disease is low. The “cascade” of follow-up tests costs substantial sums (the point of this blog). This cascade also causes discomfort and anxiety –and sometimes real damage to patients.