from therapeutics
Preventive medicine

The rationale for preventive medicine is to identify risk factors in
each individual and reduce or eliminate those risks in an attempt to
prevent disease. Primary prevention is the preemptive behavior that
seeks to avert disease before it develops--for example, vaccinating
children against diseases. Secondary prevention is the early detection
of disease or its precursors before symptoms appear, with the aim of
preventing or curing it. Examples include regular cervical Papanicolaou
test screening and mammography. Tertiary prevention is an attempt to
stop or limit the spread of disease that is already present. Clearly,
primary prevention is the most cost-effective method of controlling
disease. 

The five leading causes of death in the United States are cardiovascular
disease, cancer, cerebrovascular disease, accidental injuries, and
chronic lung disease. The single most preventable cause of death in the
United States is cigarette smoking, which is linked to cardiovascular
disease (heart attack), cancer (lung, larynx, bladder, pancreas, and so
on), cerebrovascular disease (stroke), and chronic lung disease
(emphysema, chronic bronchitis). 

Following earlier work by the Canadian Task Force on the Periodic Health
Examination, the U.S. Preventive Services Task Force was established to
evaluate the effectiveness of various screening tests, immunizations,
and prophylactic regimens based on a critical review of the scientific
literature. Its report, Guide to Clinical Preventive Services, lists the
recommendations for the 60 target conditions evaluated by the panel. 

Immunization is the best method for preventing infectious diseases.
Standard immunizations of infants and children include those for
diphtheria, tetanus, and pertussis (DTP); polio (OPV); measles, mumps,
and rubella (MMR); Haemophilus influenzae type b (HbCV); and hepatitis B
(HBV). A yearly vaccine against the influenza virus should be
administered to adults who are older than 65 years of age, to those at
risk because of chronic cardiopulmonary disease, and to those in chronic
care facilities. Adults also should be immunized once at age 65 years
against pneumococcal pneumonia with a vaccine containing 23 of the most
common strains of Streptococcus pneumoniae (Table 4). 

Acquired immunodeficiency syndrome (AIDS), caused by the human
immunodeficiency virus (HIV), is also a major infectious disease
problem. Although a vaccine is expected, obstacles to its development
are great. The only primary preventive measures currently available are
either to abstain from sexual contact or to use condoms and, among
intravenous drug users, to avoid sharing needles. Almost 25 percent of
adult AIDS cases in the United States are related to infection from
needles used to administer illegal drugs. 

The risk factors for coronary artery disease that can be modified to
prevent myocardial infarction are cigarette smoking, hypertension, an
elevated serum cholesterol level, a sedentary lifestyle, obesity,
stress, and excessive alcohol consumption. In addition to an elevated
total serum cholesterol level, an elevated low-density lipoprotein (LDL)
level and a decreased high-density lipoprotein (HDL) level are
significant risk factors. The total cholesterol level and elevated LDL
level can be reduced by appropriate diet, whereas a low HDL can be
raised by stopping smoking and increasing activity. If these measures do
not provide adequate control, a variety of drugs capable of lowering the
cholesterol level are available. 

The major risk factor for stroke is hypertension, with cigarette smoking
and diabetes mellitus significantly increasing the risk. Transient
ischemic attacks (TIAs) occur before stroke in 20 percent of patients
and consist of sudden onset of one or more of the following symptoms:
temporary loss of vision in one eye, unilateral numbness, temporary loss
of speech or slurred speech, and localized weakness of an arm or leg.
Attacks last less than 24 hours and resolve without permanent damage
until the stroke occurs. 

The most important preventive behaviour in averting cancer is the
avoidance of cigarette smoke. Smoking accounts for 30 percent of all
cancer deaths, and there is increasing recognition of the danger of
environmental or sidestream smoke to the nonsmoker. Primary prevention
of skin cancer includes restricting exposure to ultraviolet light by
using sunscreens or protective clothing. Secondary preventive measures
include mammography, clinical breast examinations, and breast
self-examinations for breast cancer; pelvic examinations and
Papanicolaou tests for cervical and ovarian cancer; and sigmoidoscopy,
digital rectal examinations, and stool tests for occult blood for
colorectal cancer. 

Demineralization of bone and a reduction in bone mass (osteoporosis)
occur most often in men and women age 70 or older and may result in
fractures, low back pain, and loss of stature. Osteoporosis in
postmenopausal women that is caused by estrogen deficiency is the most
common manifestation. The most effective method for preventing loss of
bone mass after menopause is estrogen replacement therapy and increased
calcium intake. Primary preventive measures include increasing physical
activity and avoiding cigarettes and heavy alcohol consumption. 

Alcohol abuse is the primary reason that accidents are the fourth
leading cause of death in the United States. Other factors are failure
to wear seat belts or motorcycle helmets, sleep deprivation, and guns in
the home. Taking reasonable precautions and being aware of the potential
dangers of alcohol and firearms can help reduce the number of deaths due
to accidents. 

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