The goal of preventive medicine is not only to reduce premature morbidity and mortality but also to preserve function and quality of life.
Screening techniques can be used for research and for practical disease prevention or treatment. Screening for nonresearch purposes is useful if the disease in question is
detectable with some measurable degree of reliability
treatable or preventable
significant because of its impact (prevalence or severity)
generally asymptomatic (or has symptoms a patient might deny or might not recognize)
Screening techniques should not be applied to a certain population until the following concerns have been addressed:
sensitivity and specificity of the test
convenience and comfort of the test
cost of finding a problem
cost of not finding a problem
The term sensitivity describes how often a test result is positive among persons with a target disease. Specificity measures the test’s ability to exclude truly negative results. Relative risk is the probability of a disease based on a specific finding divided by the probability of that disease in the absence of that specific finding. (See Chapter 1 in this volume for additional discussion of these terms.)
Cost can and should be measured in both economic and human terms, including the cost of discomfort, losing function, or dying.
Screening can be done as a one-time venture or by the sequential application of screening tests. Initially, a more sensitive test is administered; when appropriate, it is followed by a more specific test (which is often more costly or difficult to use). When judging the predictive value of the screens for an individual patient, the physician should account for the patient’s clinical history, current medications, and results from a physical examination.
The American College of Cardiology (ACC) and the American Heart Association (AHA) guidelines published in November 2017 define hypertension as systolic blood pressure that is greater than or equal to 130 mm Hg and/or diastolic blood pressure greater than or equal to 80 mm Hg. Hypertension currently afflicts approximately 1.4 billion people worldwide. In the United States, it affects an estimated 103 million persons aged 20 years and older; only about half of these cases are under control with treatment. In adults in the United States, the prevalence of hypertension is approximately 46% under the 2017 ACC/AHA guidelines. Hypertension in children is also becoming a more widely recognized problem.
The consequences of uncontrolled hypertension include significantly increased risk of thrombotic and hemorrhagic stroke, atherosclerotic heart disease, atrial fibrillation, congestive heart failure, left ventricular hypertrophy, aortic aneurysm and dissection, peripheral arterial disease, and renal failure. Approximately 30% of end-stage renal disease is related to hypertension.
Hypertension meets all 5 of the screening criteria mentioned previously: it is detectable, treatable, highly prevalent, progressively damaging, and characteristically asymptomatic until late in its course. See Chapter 3 in this volume for discussion of the classification, evaluation, and pharmacologic treatment of hypertension.
Whelton PK, Carey RM, Aronow WS, et al. 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA Guideline for the prevention, detection, evaluation and management of high blood pressure in adults: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. Hypertension. 2018;71(6):e13–e115.
Atherosclerotic cardiovascular disease
In the United States, atherosclerosis is responsible for approximately one-half of deaths in individuals of all ages and for one-third of deaths in individuals between 35 and 65 years of age. Three-fourths of deaths related to atherosclerosis result from coronary heart disease (CHD). Atherosclerosis is the leading cause of permanent disability and accounts for more hospital days than any other illness.
The rationale for early screening emerged after it was demonstrated that a reduction in risk factors correlated to a reduction in the incidence of coronary disease events. For further discussion on identifying and modifying cardiovascular risk factors, see Chapter 4 in this volume.
Screening for significant coronary artery atherosclerosis is more expensive and time-consuming than screening for associated reversible risk factors. In general, it is reasonable to screen for a history of cardiovascular symptoms and events (eg, chest pain, dyspnea, syncope, arrhythmias, claudication, stroke) and reserve more specific testing (eg, exercise stress testing, cardiac computed tomography [CT], or magnetic resonance imaging [MRI]) for individuals in higher-risk categories.
Excerpted from BCSC 2020-2021 series: Section 1 - Update on General Medicine. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.