The problem of overdiagnosis
May 31, 2012 Leave a comment
Narrowly defined, overdiagnosis occurs when people without symptoms are diagnosed with a disease that ultimately will not cause them to experience symptoms or early death. More broadly defined, overdiagnosis refers to the related problems of overmedicalisation and subsequent overtreatment, diagnosis creep, shifting thresholds, and disease mongering, all processes helping to reclassify healthy people with mild problems or at low risk as sick.
The problems of over diagnosis include health impacts of treatments, stigma from labeling, worry and cost. The essence of the problem is that these costs (monetary and intangible) are increasing while the benefits of any treatment available are not (mortality reduction, morbidity decline). The figures from the paper provide examples in which death rates from certain Cancers are stable over time, while cases are increasing, typically due to improved ability to detect disease and/or more attempts to do so via broader screening. Below I reproduce just one of the 5 graphs demonstrating this phenomenon with Thyroid Cancer:
Increased diagnosis suggests an explosion of cases, while death from this cause are flat. This epidemiology can produce different survival rates across nations, for example, as Aaron clearly describes in his post if different nations diagnose disease earlier; but early diagnosis only helps if it provides the route to an effective treatment. Thus, in many cases, differences in survival do not really provide a means of capturing any net benefits of treatment. However, our cultural default is to assume that more is better, and to wonder how any information from a test hurt? And even asking the question of whether some efforts to detect and/or treat disease are worth it will bring howls of protest and accusations of your wanting to kill someones grandmother in the U.S. political context.
There is no technical way to address this problem. What is needed most is cultural change, that first and foremost leads each of us, and us collectively, to ask the following questions about any test or treatment:
- Does it extend life?
- Does it improve quality of life?
- How much does it cost? (with a very broad notion of costs, not only financial)
Only by answering these 3 questions can you have a hope of determining whether something is “worth it.” It is often hard to answer these questions well, or clearly, and I don’t mean to minimize this. However, the first step is to learn to even ask them.