The apples and oranges of cost-effectiveness

CAN PREVENTION BE COMPARED WITH TREATMENT?

This leaves us with the final and most difficult question. Is it right to compare such things?

Having terminal cancer is a different experience than having high cholesterol, and this is the last apple and orange of cost-effectiveness. While a strict utilitarian view of medicine might find these cases indistinguishable, most practitioners and payers are not strict utilitarians. As a society, we tend to favor paying more to treat someone who is ill than paying an equivalent amount to prevent illness. Often, such a stance is criticized as a failure to invest in prevention and primary care, but another explanation is that the bias is a fundamental one of human risk-taking.

Cost-effectiveness is, to a certain degree, a slippery concept, and it is more likely to be “off” when a therapy is given broadly (to hundreds of thousands of people as opposed to hundreds) and taken in a decentralized fashion by individual patients (as opposed to directly observed therapy in an infusion suite). Accordingly, we may favor more expensive therapies, the cost-effectiveness of which can be estimated more precisely.

A recent meta-analysis of statins for primary prevention in high-risk patients found that they were not associated with improvement in the overall rate of death.⁸ Such a finding dramatically alters our impression of their cost-effectiveness and may explain the bias against investing in such therapies in the first place.

IMPROVING COST-EFFECTIVENESS RESEARCH

Studies of cost-effectiveness are not equivalent. Currently, such studies are apples and oranges, making difficult the very comparison that cost-effectiveness should facilitate. Knowing that a therapy is efficacious should be prerequisite to cost-effectiveness calculations, as should performing calculations under real-world conditions.

Regarding efficacy, it is inappropriate to calculate cost-effectiveness from trials that use only surrogate end points, or those that are improperly controlled.

For example, adding extended-release niacin to statin therapy may raise high-density lipoprotein cholesterol levels by 25%. Such an increase is, in turn, expected to confer a certain reduction in cardiovascular events and death. Thus, the cost-effectiveness of niacin might be calculated as $20,000 per life-year saved. However, adding extended-release niacin to statin therapy does not improve hard outcomes when directly measured,⁹ and the therapy is not efficacious at all. Its true “dollars per life-year saved” approaches infinity.

Studies that use historical controls, are observational, and are performed at single centers may also mislead us regarding a therapy’s efficacy. Tight glycemic control in intensive care patients initially seemed promising^10,11 and cost-effective.¹² However, several years later it was found to increase the mortality rate.¹³

“Real world” means that the best measures of cost-effectiveness will calculate the cost per life saved that the therapy achieves in clinical practice. Adherence to COX-2 inhibitors may not be as strict in the real world as it is in the carefully selected participants in randomized controlled trials, and, thus, the true costs may be higher. A drug that prevents breast cancer may have countervailing effects that may as yet be unknown, or compliance with it may wane over years. Thus, the most accurate measures of cost-effectiveness will examine therapies as best as they can function in typical practice and likely be derived from data sets of large payers or providers.

Finally, it remains an open and contentious issue whether the cost-effectiveness of primary prevention and the cost-effectiveness of treatment are comparable at all. We must continue to ponder and debate this philosophical question.

Certainly, these are the challenges of cost-effectiveness. Equally certain is that—with renewed consideration of the goals of such research, with stricter standards for future studies, and in an economic and political climate unable to sustain the status quo—the challenges must be surmounted.