Surveying the health landscape
Whether applied to individual patients or populations, disease screening is an essential component of modern disease management programs.
Screening interventions can be thought of as a means of risk assessment; before performing costly diagnostic tests on an asymptomatic or mildly symptomatic individual, it is possible to identify predispositions (e.g., genetics, lifestyle) that increase chances of a disease developing later. If one or more of these risk markers associated with a particular disease are identified in that individual, a focused management effort can then be made to minimize the chances of the disease occurring, or at least mitigate the harm and severity should an actual diagnosis be made in the future.
Screening methods can vary widely in their effectiveness.
While lifestyle and other behavioral markers may be relatively easy to identify, testing for the presence of genetic and other physiological markers is more susceptible to error that can result in alarming false positives that consume valuable time and financial resources, or false negatives that give an unwarranted “out of danger” sense to test recipients. Therefore, it is critical that screening tests are selected carefully, refined to be as sensitive as possible and highly specific to the disease being screened, with marginal chance for error.
Screening can be done universally on a large population segment when a disease is common and serious enough to warrant it (e.g., regular mammograms for women over 40 years of age), or selectively when a smaller subset of the population is considered at especially high risk (e.g., regular COVID-19 testing within the healthcare worker community).
The type of screening performed is highly dependent on:
- Frequency of disease occurrence
- Medical cost factors
- Existing treatment options for those who may eventually be diagnosed with a disease
Positive Screening ≠ Positive Diagnosis
It’s important to understand that a positive screen is not the same as a positive diagnosis. Rather, screening tests are used to identify a portion of the population who would benefit from additional testing to determine the presence or absence of disease. Only at this later stage of testing can a diagnosis be determined, and treatment options explored.
In terms of effective disease management and population health, however, well-applied medical screening programs continue to aid in earlier disease detection and intervention, reducing mortality and improving the quality of life for millions of affected individuals worldwide.