What is disease? One of the largest challenges of epidemiology is generating a definition of a illness that is both balanced between narrow and broad-based specifications, and is accurate to the population considered within the definition. Epidemiologists, researchers, policy makers, and teaching professionals across the globe are struggling in their ability to create disease definitions that correspond with the multitude of symptoms potentially placing patients within that illness category. This day-to-day challenge restricts public health officials' proficiency in creating successful programs, treatments, and prevention strategies for the community. "No case definition is perfect; every disease has outliers. But whether a definition is broadly or narrowly drawn can profoundly affect the statistics vital for public health planning," as stated by author David Tuller, of the New York Times.
When similarly reoccurring disease symptoms are observed in enough people within a specific time period, a case definition is needed so that classifications of presence and severity of the disease can be constructed. These classifications allow public health professionals to assess the event. If a disease definition is too broad or too narrow, then this act becomes increasingly more strenuous. "You need to know whether the numbers are going up or down, or whether treatment and prevention work. And if you have a bad case definition, then it's very difficult to figure out what's going on," says Professor of Epidemiology Andrew Moss of the University of California - San Francisco.
These challenges were illustrated in recent studies of workers suffering from carpal tunnel syndrome. It was found that a range of 2.5%, all the way to 11%, of the workers were diagnosed with carpal tunnel syndrome. This broad range of potential sufferers is attributed to the type of test performed on each individual, whether it be a physical exam, nerve tests, or simply reported symptoms. In another study of acute gastroenteritis, it was found that the number of diagnoses doubled when the case definition of the illness was loosened to encompass more people.
"If researchers filter their perceptions through different lenses — that is, case definitions that generate study populations varying in size and characteristics — it is hard to know whether they are studying the same phenomenon, overlapping ones or completely unrelated ailments. Determining whether findings from one study can be extrapolated to other patients becomes difficult at best" (Tuller).
Communication between epidemiologists is essential to understanding a disease. Defining the characteristics of it and using the same criteria for diagnosing it allows epidemiologists to see the illness through the same lens, and thus collaborate to treat and prevent it within the population.
I really liked this post, particularly because it perfectly ties into important discussions that have taken place during class. The first class activity that comes to mind was the one that included the SLU community. A new and potentially dangerous strain of the flu had hit SLU, and it was our job to come up with a plan of attack. What was central to this plan, however, was how we defined the disease based on its symptoms. This proved very challenging for my group in particular, as nobody could agree on a disease definition.
ReplyDeleteIt makes me think how crucial the job of an epidemiologist must be as well, as there have been several cases of potentially dangerous diseases that have struck America within the past decade: West Nile virus and the Swine Flu. Therefore, although the concept of defining a disease may seem simple, the definition is crucial to how the public goes about treating and preventing the disease.