As research findings accumulate, health professionals are becoming better and better at identifying people who are at risk of developing a variety of health problems. Moreover, knowledge is accumulating at a rapidly escalating pace, especially since the human genome has been specified. The idea that one can identify at birth whether an infant is more or less likely to suffer from diseases later in life is no longer the stuff of science fiction. This entry describes what is known about how to screen for risk and some of the factors that elevate risk, who gets screened, and the consequences of risk factor screening.
Screening For Risk
Four general methods are available to identify people who are at risk of developing different diseases. Perhaps the oldest, simplest, and least expensive approach is to ask people to report information about their background and behavior. Background characteristics can be important predictors of risk for disease. For example, Black men are more at risk of prostate cancer than White men, and Black men and women in the United States face a higher risk than Whites for the sickle cell trait. White women, on the other hand, are more likely to suffer from osteoporosis than Black women. Other important background characteristics besides race and gender are family history, income, and education. Family history is an especially important variable, in part because a strong family history of disease suggests that a person is more likely to have a genetic predisposition for the disorder.
In addition to background characteristics, risk factor screening often includes the identification of current behaviors or behavior patterns (i.e., personality) related to disease. A person who smokes cigarettes, for example, is at great risk of numerous diseases, including a variety of different cancers and heart disease, the two biggest causes of early death in the United States. Overweight individuals are also at higher risk of disease, especially coronary heart disease, and individuals who are inactive also place themselves at higher risk for illness. Persons who combine these types of risk factors are at the greatest risk: Type II diabetes, for example, is typically associated with a family history of diabetes, being overweight, and inactivity. Finally, one can also assess personality dimensions. Perhaps the best known of these is the Type A personality. Psychologist Tim Smith has shown that the hostility component of this personality type is a good predictor of later heart disease.
A third means of identifying people at risk is to conduct some type of medical screening that can alert a health professional about the probability of disease. Such screenings are becoming available for more and more diseases, but it is important to recognize that these tests are imperfect: They can produce correct identification, but also false positives (indicating risk when there is actually none) and false negatives (indicating no risk when risk actually exists). Examples of this type of screening include mammography (for breast cancer), cholesterol levels (for heart disease), prostate-specific antigen tests (for prostate cancer), and blood pressure measurement (for stroke).
The final way to identify people at risk is to determine whether they have a gene associated with the disease. In the past, genetic screening was accomplished by constructing extensive family histories of persons with the disease. More recently, health professionals can collect genetic material (typically from blood) and identify whether the genes are predictive of the disease. Such tests will be more available in the future, but it is important to recognize that genes are not necessarily destiny. For breast cancer, as an example, estimates are that a young woman with the BRCA1 gene has greater than a 50/50 chance of developing breast cancer in her lifetime. The vast majority of breast cancers, perhaps as many as 90%, are not associated with any particular genetic abnormality.
Who Gets Screened?
The most powerful predictor of whether a person will get screened is probably a physicians recommendation. Indeed, some risk factor screening is done almost automatically at a physician visit, including recording weight and blood pressure. A recommendation for more invasive screening by a physician is likely to be based on the doctors knowledge of a patient’s personal characteristics, such as a family history of the disease. People also can get screened for some risks in the community. For example, some employers might screen everyone at their worksite. It is also the case that people who feel at risk—who feel vulnerable and worry about contracting disease—are likely to seek out screening. In this case, objective risk factors may be less important than the person’s beliefs about his or her susceptibility to disease. It is worth noting that disparities in screening rates exist among different groups. Persons of lower socioeconomic status are less likely to have been screened for a variety of diseases. Less frequent or delayed screenings can have important negative consequences in that some diseases may be detected later after the illness has progressed further and is more difficult to treat successfully.
A number of barriers have also been indicated as inhibitors of screening. These include such factors as the costs of screening, difficulties obtaining a screening (e.g., transportation problems, lack of time), and concerns about the screening test itself (e.g., fear of radiation, worry about pain).
Consequences Of Screening
The purpose of screening is to identify risks that, if addressed, may allow people to minimize or avoid disease. How people react to learning that they are at risk depends on the answer they receive. When people receive a negative message (e.g., “Your cholesterol is 250, which is higher than we would like”), they usually respond defensively, trying to minimize the threat inherent in the information. A person might, for example, deemphasize the seriousness of the disease (e.g., “People recover from heart attacks”), question the reliability of the screening test (e.g., “You can’t trust these cholesterol readings anyway”), or think about alternative ways to reduce the severity of the threat (e.g., “My high score doesn’t matter, because I exercise three times a week and exercise lowers blood pressure”). In summary, when a person receives a threatening message about elevated risk of health problems, he or she is motivated to reduce the negative implications of that information.
People are much more likely to eagerly accept information that they are not at risk. Even here, though, evidence suggests that people will sometimes reject information that they are less at risk than they had believed before testing. For example, researchers have provided risk counseling to women who overestimate their risk of breast cancer. These women learn that their risk is lower than they had thought, but many of them fail to adopt the new risk level: To some extent, they continue to maintain their original belief. People may retain their old beliefs because they wish to hedge their bets, and thus they may note that the new risk information fails to take into account special circumstances. It may also be the case that women avoid new risk information because it interferes with a consistent view of the self, even if this view is somewhat negative.
It is probably possible to communicate risk so that defensive reactions are lessened, but much needs to be learned about the risk communication process. It has been learned that it is possible in some circumstances to change inaccurate perceptions. In a large study of more than 1,000 patients waiting for medical care, Matthew W. Kreuter and Victor J. Strecher measured risk perceptions and provided individualized risk feedback about stroke, cancer, heart attack, and car crashes. The feedback increased stroke risk for those who were underestimating and reduced cancer risk for those who were overestimating. The feedback had no effect, however, on perceived risks of heart attack or car crashes. Not only is it possible to change some risk perceptions, the evidence is also solid that risk information can prompt people to protect their health. Smokers, for example, are more likely to quit when their physician reminds them about their increased health risk and advises them to quit. People with a family history of disease are much more likely to seek out screening, and to adopt behaviors that might lower their chances of contracting the health problem. Although we may not yet know the best ways to communicate risk information so as to persuade people to change their risk perceptions, we do know that the provision of such information can have positive benefits in motivating behavior change among those at greater risk of disease.