Treating laboratory values instead of patients is not yet the standard for optimal care. Our trial-based clinical judgment still may be the best medicine for our patients.
The mainstay of dentistry for the past decades has been the prevention and treatment of chronic diseases. Caries and periodontal disease are two of the most prevalent infectious diseases in the world, affecting billions of people. Tremendous efforts in prevention through education, fluoridation, sealants, improved formulations of antibacterial toothpastes and more advanced toothbrushes have reduced the morbidity of these diseases significantly. Traditionally, prevention has been provided indiscriminately to all comers. However, where financial resources and access to care are scarce or limited, targeting only patients at risk of developing disease would benefit all patients.
Screening of asymptomatic patients for the risk of developing disease is emerging as an innovative concept in preventive medicine. On the surface, this seems to be a great idea. Raise the concept of preventive medicine to a level at which the risk of developing disease can be quantified and addressed. Who could argue that this type of preventive medicine, instead of relief, is a bad idea? Wouldn’t primary prevention (that is, preventing a disease from occurring in the first place) always be better than secondary prevention (that is, preventing a disease from reoccurring)? These are important concepts that all health care providers must address.
Looking at the medical model, one can see several examples in which screening for the risk of developing disease should result intuitively in the institution of preventive measures. However, this is not always the case. More than four million Americans may be infected with the hepatitis C virus, or HCV. The vast majority of them are unaware of their infection, yet approximately 8 percent of infected people will develop cirrhosis within 20 years.
Wouldn’t it be beneficial if we could identify all people infected with HCV to institute early interventions and maybe prevent further transmission? A recent article addressed the implications of screening the general adult population for HCV.1 The authors’ conclusion was to reject a recommendation for generalized HCV screening. A number of arguments against generalized screening were offered—labeling of a person as diseased, for example, as well as adverse treatment effects and unnecessary biopsies.
Another conundrum centers on if or when to implement therapy for asymptomatic people when the risk assessment changes. New recommendations for treatment and new classifications of blood pressure and hypertension were published in May 2003.2 These new guidelines were introduced, in part, because of new data indicating that the level previously designated as "normal" blood pressure (> 120–139/80–99 millimeters of mercury [mm Hg]) was already placing a person at an increased risk of developing heart disease. Consequently, in the most recent guidelines this blood pressure level is designated as "prehypertensive" and "normal" blood pressure levels are defined as < 120/80 mm Hg.
To achieve "normal" blood pressure, many more patients are going to receive medications along with other interventions. A question that begs to be asked is whether more aggressive therapy to achieve this new goal is more harmful than the potential risk of developing cardiovascular disease. Or, perhaps equally important, is it possible to apply this paradigm to all people?
Another example is the popular full-body scan, or "heart-scan," used to determine the level of calcium in coronary arteries. This technology quantifies the amount of calcium in the wall of an artery that should correlate with the severity of coronary artery blockage. However, results from this new diagnostic scan generate questions for which there are as yet no answers: At what level of calcium build-up is intervention justified in asymptomatic patients? What should patients be told about their condition, and what should the patients do with that information?
These examples demonstrate three different circumstances in which limited examination findings, laboratory markers or tests of asymptomatic patients may reveal a potential risk of developing disease. The decision to intervene and the rationale for doing so differ with each scenario.
If presented with all available facts, can a patient—or even an informed health care provider—always determine an optimal benefit-to-risk ratio? No disease process is straightforward. Ancestry, genetics, behavior, environmental circumstances, socioeconomic strata and level of education are a few of the many factors that have been shown to affect morbidity and mortality of disease.
Increased technological advances and understanding of disease processes soon may change laboratory medicine from being able only to exclude disease to possibly being able to test for health. At present there is no test for health; there are only tests that exclude illness. But what if we were able to completely understand the consequence of the human genome? Would we not then be able to predict both health and disease? Even though using genetic markers to determine a person’s risk of developing periodontal disease has been proposed, we are far from generalizing such a celestial goal for overall oral health.
The practice of dentistry will change dramatically during the next decade. Use of genetically based diagnostic tests will drive preventive efforts, while personalized targeted treatments—including pharmaceutical therapy—will guide treatment interventions.
Treating laboratory values instead of patients is not yet the standard for optimal care. Until we can assess and incorporate all factors in the decision-making process to determine risk of disease, our trial-based clinical judgment still may be the best medicine for our patients.
