Mortality rates of cancer have begun to decrease in the past 2 years; part of this decrease results from reductions in tobacco use, since cigarette smoking is the most important preventable cause of cancer. Primary prevention of skin cancer consists of restricting exposure to ultraviolet light by wearing appropriate clothing and use of sunscreens. In the past 2 decades, there has been a threefold increase in the incidence of squamous cell carcinoma and a fourfold
increase in melanoma in the United States. Persons who engage in regular physical exercise and avoid obesity have lower rates of breast and colon cancer. Prevention of occupationally induced cancers involves minimizing exposure to carcinogenic substances such as asbestos, ionizing radiation, and benzene compounds. Chemoprevention has been widely studied for primary cancer prevention, but large trials in women taking aspirin, vitamin E, or calcium and vitamin D did not find reductions in cancer incidence or mortality. Use of tamoxifen, raloxifene, and aromatase inhibitors for breast cancer prevention. Hepatitis B vaccination can prevent hepatocellular carcinoma, and the development of an HPV vaccine holds promise for prevention of cervical cancer.
Saturday, February 28, 2009
Thursday, February 26, 2009
Chemoprevention
As discussed, regular use of low-dose aspirin (81–325 mg) can reduce the incidence of myocardial infarction in men. Low-dose aspirin reduces stroke but not myocardial infarction in middle-aged women. Antioxidant vitamin (vitamin E, vitamin C, and beta-carotene) supplementation produced no significant reductions in the 5-year incidence of—or mortality from—vascular disease, cancer, or other major outcomes in high-risk individuals with coronary artery disease, other occlusive arterial disease, or diabetes mellitus.
Wednesday, February 25, 2009
Hypertension
Over 43 million adults in the United States have hypertension, but 31% are unaware of their elevated blood pressure; 17% are aware but untreated; 29% are being treated but have not
controlled their blood pressure (still greater than 140/90 mm Hg); and only 23% are well controlled. In every adult age group, higher values of systolic and diastolic blood pressure
carry greater risks of stroke and congestive heart failure.Systolic blood pressure is a better predictor of morbid events than diastolic blood pressure. Clinicians can apply specific blood pressure criteria, such as those of the Joint National Committee, to decide at what levels treatment should be considered in individual cases. Table 11–1 presents a classification of hypertension based on blood pressures.
Primary prevention of hypertension can be accomplished by strategies aimed at both the general population and special high-risk populations. The latter include persons with high-normal blood pressure or a family history of hypertension, blacks, and individuals with various behavioral risk factors such as physical inactivity; excessive consumption of salt, alcohol, or calories; and deficient intake of potassium. Effective interventions for primary prevention of hypertension include reduced sodium and alcohol consumption, weight loss, and regular exercise. Potassium supplementation lowers blood pressure modestly, and a diet high in fresh fruits and vegetables and low in fat, red meats, and sugar-containing beverages also reduces blood pressure.
Interventions of unproven efficacy include pill supplementation of potassium, calcium, magnesium, fish oil, or fiber; macronutrient alteration; and stress management.
Improved diagnosis and treatment of hypertension is a major cause of the recent decline in stroke deaths. Hypertension control, however, remains suboptimal. An intervention that included patient education and provider education was more effective than provider education alone in achieving control of hypertension, suggesting the benefits of patient participation in hypertension treatment.
controlled their blood pressure (still greater than 140/90 mm Hg); and only 23% are well controlled. In every adult age group, higher values of systolic and diastolic blood pressure
carry greater risks of stroke and congestive heart failure.Systolic blood pressure is a better predictor of morbid events than diastolic blood pressure. Clinicians can apply specific blood pressure criteria, such as those of the Joint National Committee, to decide at what levels treatment should be considered in individual cases. Table 11–1 presents a classification of hypertension based on blood pressures.
Primary prevention of hypertension can be accomplished by strategies aimed at both the general population and special high-risk populations. The latter include persons with high-normal blood pressure or a family history of hypertension, blacks, and individuals with various behavioral risk factors such as physical inactivity; excessive consumption of salt, alcohol, or calories; and deficient intake of potassium. Effective interventions for primary prevention of hypertension include reduced sodium and alcohol consumption, weight loss, and regular exercise. Potassium supplementation lowers blood pressure modestly, and a diet high in fresh fruits and vegetables and low in fat, red meats, and sugar-containing beverages also reduces blood pressure.
Interventions of unproven efficacy include pill supplementation of potassium, calcium, magnesium, fish oil, or fiber; macronutrient alteration; and stress management.
Improved diagnosis and treatment of hypertension is a major cause of the recent decline in stroke deaths. Hypertension control, however, remains suboptimal. An intervention that included patient education and provider education was more effective than provider education alone in achieving control of hypertension, suggesting the benefits of patient participation in hypertension treatment.
Saturday, February 21, 2009
Hyperhomocysteinemia
Elevated plasma homocysteine may be an independent risk factor for coronary artery disease. Elevated levels can be reduced with folate and pyridoxine treatment and with smoking cessation (although not smoking reduction), but their clinical significance is unknown. Randomized trials of
vitamin supplementation in patients with prior cardiovascular disease have generally yielded negative results. At this time, there is insufficient evidence to justify screening for elevated serum homocysteine, but patients should be encouraged to maintain an adequate dietary intake of
folate, pyridoxine (vitamin B6), and vitamin B12.
vitamin supplementation in patients with prior cardiovascular disease have generally yielded negative results. At this time, there is insufficient evidence to justify screening for elevated serum homocysteine, but patients should be encouraged to maintain an adequate dietary intake of
folate, pyridoxine (vitamin B6), and vitamin B12.
Lipid Disorders
Higher low-density lipoprotein (LDL) cholesterol concentrations and lower high-density lipoprotein (HDL) levels are associated with an increased risk of CHD. Elevated triglyceride levels and elevated plasma lipoprotein(a) are also independent risk factors for CHD. The absolute benefits of screening for—and treating—abnormal lipid levels depend on the presence of other cardiovascular risk factors. If other risk factors are present, cardiovascular risk is higher and the benefits of therapy are greater. Patients with diabetes mellitus or known cardiovascular disease are at still higher risk and benefit from treatment even when lipid levels are normal.
Evidence for the effectiveness of statin-type drugs is better than for the other classes of lipidlowering agents. Multiple large randomized, placebo-controlled trials have demonstrated important reductions in total mortality, major coronary events, and strokes with lowering levels of LDL cholesterol by statin therapy for patients with known cardiovascular disease. Statins also reduce cardiovascular events for patients with diabetes. For patients with no previous history
of cardiovascular events, statins reduce coronary events for men, but less evidence is available for women.
Evidence for the effectiveness of statin-type drugs is better than for the other classes of lipidlowering agents. Multiple large randomized, placebo-controlled trials have demonstrated important reductions in total mortality, major coronary events, and strokes with lowering levels of LDL cholesterol by statin therapy for patients with known cardiovascular disease. Statins also reduce cardiovascular events for patients with diabetes. For patients with no previous history
of cardiovascular events, statins reduce coronary events for men, but less evidence is available for women.
Prevention Of Cardiovascular Disease
Cardiovascular diseases, including coronary heart disease (CHD) and stroke, represent two of the most important causes of morbidity and mortality in developed countries. Several risk factors increase the risk for coronary disease and stroke. They can be divided into those that are modifiable (eg, lipid disorders, hypertension, cigarette smoking) and those that are not (eg, gender, age, family history of early coronary disease). This section considers the role of screening for and treating modifiable risk factors.
Impressive declines in age-specific mortality rates from heart disease and stroke have been achieved in all age groups in North America during the past 2 decades. The chief reasons for this favorable trend appear to be modification of risk factors, especially cigarette smoking and hypercholesterolemia, plus more aggressive detection and treatment of hypertension and better care for patients with heart disease. In addition, it now appears that screening for abdominal aortic aneurysm in men aged 65–75 years is associated with a significant reduction in mortality (odds ratio, 0.57 [95% CI, 0.45 to 0.74]); this benefit has not been found for women.
Cigarette Smoking
Cigarette smoking remains the most important cause of preventable morbidity and early mortality. In 2000, there were an estimated 4.8 million premature deaths in the world attributable to smoking, 2.4 million in developing countries and 2 million in industrialized countries. More than three-quarters (3.8 million) of these deaths were in men. The leading causes of death from smoking were cardiovascular diseases (1.7million deaths), chronic obstructive pulmonary disease (COPD) (1 million deaths), and lung cancer (0.9 million deaths). Nicotine is highly addictive, raises brain levels of dopamine, and produces withdrawal symptoms on discontinuation. Cigarettes are responsible for one in every five deaths in the United States, yet smoking prevalence rates have been increasing among high school and college students. Cigar smoking has also increased; there is also continued use of smokeless tobacco (chewing tobacco and snuff), particularly among young people. Tobacco dependence may have a genetic component.
Smokers have twice the risk of fatal heart disease, 10 times the risk of lung cancer, and several times the risk of cancers of the mouth, throat, esophagus bladder, and cervix; a twofold to threefold higher incidence of stroke and peptic ulcers (which heal less well than in nonsmokers); a twofold to fourfold greater risk of fractures of the hip, wrist, and vertebrae; four times the risk of invasive pneumococcal disease; and a twofold increase in cataracts. In the United States, over 90% of cases of COPD occur among current or former smokers. Both active smoking and passive smoking are associated with deterioration of the elastic properties of the aorta (increasing the risk of aortic aneurysm) and with progression of carotid artery atherosclerosis. Smoking has also been associated with increased risks of leukemia, of colon and prostate cancers, of breast cancer among postmenopausal women who are slow acetylators of N-acetyltransferase-2 enzymes,osteoporosis, and Alzheimer’s disease. In cancers of the head and neck, lung, esophagus, and bladder, smoking is linked to mutations of the P53 gene, the most common genetic change in human cancer. Patients with head and neck cancer who continue to smoke during radiation therapy have lower rates of response than those who do not smoke. Olfaction and taste are impaired in smokers, and facial wrinkles are increased. Heavy smokers have a 2.5 greater risk of age-related macular degeneration. Smokers die 5–8 years earlier than never-smokers.
The children of smokers have lower birth weights, are more likely to be mentally retarded, have more frequent respiratory infections and less efficient pulmonary function, have a higher incidence of chronic ear infections than children of nonsmokers, and are more likely to become smokers themselves. In addition, exposure to environmental tobacco smoke has been shown to increase the risk of cervical cancer, lung cancer, invasive pneumococcal disease, and heart disease; to promote endothelial damage and platelet aggregation; and to increase urinary excretion of tobacco-specific lung carcinogens. The incidence of breast cancer may be increased as well. Of approximately 450,000 smoking-related deaths in the United States annually, as many as 53,000 are attributable to environmental tobacco smoke. Smoking cessation lessens the risks of death and of myocardial infarction in people with coronary artery disease; reduces the rate of death and acute myocardial infarction in patients who have undergone percutaneous coronary revascularization; lessens the risk of stroke; slows the rate of progression of carotid atherosclerosis; and is associated with improvement of COPD symptoms. On average, women smokers who quit smoking by age 35 add about 3 years to their life expectancy, and men add more than 2 years to theirs. Smoking cessation can increase life expectancy even for those who stop after the age of 65. Fortunately, adult rates in the United States are now at an all-time low—23%—but rates are climbing for young people.
Although tobacco use constitutes the most serious common medical problem, it is undertreated. Over 70% of smokers see a physician each year, but only 20% of them receive any medical quitting advice or assistance. (Persons whose physicians advise them to quit are 1.6 times as likely to attempt quitting.) About 4% of smokers are able to quit each year., pancreas, kidney. A system should be implemented to identify smokers, and advice to quit should be tailored to the patient’s level of readiness to change. Pharmacotherapy to reduce cigarette consumption is ineffective in smokers who are unwilling or not ready to quit. Conversely, all patients trying to quit should be offered pharmacotherapy except those with medical contraindications, women who are pregnant or breastfeeding, and adolescents.
Several pharmacologic therapies have been shown to be effective in promoting cessation. Nicotine replacement therapy doubles the chance of successful quitting. The nicotine patch, gum, and lozenges are available over-the-counter, and nicotine nasal spray and inhalers by prescription. When the spray is combined with the patch, cessation rates are substantially higher. The sustained-release antidepressant drug bupropion (150–300 mg/d orally) is an effective smoking cessation agent and is associated with minimal weight gain, although seizures are a contraindication. It acts by boosting brain levels of dopamine and norepinephrine, mimicking the effect of nicotine. Bupropion, either alone or in combination with a nicotine patch, has been shown to produce significantly higher abstinence rates (30–35% at 1 year) than either a patch alone or placebo. Weight gain was less in the combined program.
More recently, varenicline, a partial nicotinic acetylcholine-receptor agonist, has shown promise as an effective agent. Weight gain occurs in most patients (80%) following smoking cessation. For many it averages 2 kg, but for others (10–15%) major weight gain—over 13 kg—may occur. Clinicians should not show disapproval of patients who have not stopped smoking or who are not ready to make a quit attempt. Thoughtful advice that emphasizes the benefits of cessation and recognizes common barriers to success can increase motivation to quit and quit rates. An intercurrent illness such as acute bronchitis or acute myocardial infarction may motivate even the most addicted smoker to quit. Individualized or group counseling is very cost effective, even more so than treating hypertension. Smokking cessation counseling by telephone (“quitlines”) has proved effective. An additional strategy is to recommend that any smoking take place out of doors to limit the effects of passive smoke on housemates and coworkers. This can lead to smoking reduction and quitting. The clinician’s role in smoking cessation is summarized in. Public policies, including higher cigarette taxes and more restrictive public smoking laws, have also been shown to encourage cessation.
Impressive declines in age-specific mortality rates from heart disease and stroke have been achieved in all age groups in North America during the past 2 decades. The chief reasons for this favorable trend appear to be modification of risk factors, especially cigarette smoking and hypercholesterolemia, plus more aggressive detection and treatment of hypertension and better care for patients with heart disease. In addition, it now appears that screening for abdominal aortic aneurysm in men aged 65–75 years is associated with a significant reduction in mortality (odds ratio, 0.57 [95% CI, 0.45 to 0.74]); this benefit has not been found for women.
Cigarette Smoking
Cigarette smoking remains the most important cause of preventable morbidity and early mortality. In 2000, there were an estimated 4.8 million premature deaths in the world attributable to smoking, 2.4 million in developing countries and 2 million in industrialized countries. More than three-quarters (3.8 million) of these deaths were in men. The leading causes of death from smoking were cardiovascular diseases (1.7million deaths), chronic obstructive pulmonary disease (COPD) (1 million deaths), and lung cancer (0.9 million deaths). Nicotine is highly addictive, raises brain levels of dopamine, and produces withdrawal symptoms on discontinuation. Cigarettes are responsible for one in every five deaths in the United States, yet smoking prevalence rates have been increasing among high school and college students. Cigar smoking has also increased; there is also continued use of smokeless tobacco (chewing tobacco and snuff), particularly among young people. Tobacco dependence may have a genetic component.
Smokers have twice the risk of fatal heart disease, 10 times the risk of lung cancer, and several times the risk of cancers of the mouth, throat, esophagus bladder, and cervix; a twofold to threefold higher incidence of stroke and peptic ulcers (which heal less well than in nonsmokers); a twofold to fourfold greater risk of fractures of the hip, wrist, and vertebrae; four times the risk of invasive pneumococcal disease; and a twofold increase in cataracts. In the United States, over 90% of cases of COPD occur among current or former smokers. Both active smoking and passive smoking are associated with deterioration of the elastic properties of the aorta (increasing the risk of aortic aneurysm) and with progression of carotid artery atherosclerosis. Smoking has also been associated with increased risks of leukemia, of colon and prostate cancers, of breast cancer among postmenopausal women who are slow acetylators of N-acetyltransferase-2 enzymes,osteoporosis, and Alzheimer’s disease. In cancers of the head and neck, lung, esophagus, and bladder, smoking is linked to mutations of the P53 gene, the most common genetic change in human cancer. Patients with head and neck cancer who continue to smoke during radiation therapy have lower rates of response than those who do not smoke. Olfaction and taste are impaired in smokers, and facial wrinkles are increased. Heavy smokers have a 2.5 greater risk of age-related macular degeneration. Smokers die 5–8 years earlier than never-smokers.
The children of smokers have lower birth weights, are more likely to be mentally retarded, have more frequent respiratory infections and less efficient pulmonary function, have a higher incidence of chronic ear infections than children of nonsmokers, and are more likely to become smokers themselves. In addition, exposure to environmental tobacco smoke has been shown to increase the risk of cervical cancer, lung cancer, invasive pneumococcal disease, and heart disease; to promote endothelial damage and platelet aggregation; and to increase urinary excretion of tobacco-specific lung carcinogens. The incidence of breast cancer may be increased as well. Of approximately 450,000 smoking-related deaths in the United States annually, as many as 53,000 are attributable to environmental tobacco smoke. Smoking cessation lessens the risks of death and of myocardial infarction in people with coronary artery disease; reduces the rate of death and acute myocardial infarction in patients who have undergone percutaneous coronary revascularization; lessens the risk of stroke; slows the rate of progression of carotid atherosclerosis; and is associated with improvement of COPD symptoms. On average, women smokers who quit smoking by age 35 add about 3 years to their life expectancy, and men add more than 2 years to theirs. Smoking cessation can increase life expectancy even for those who stop after the age of 65. Fortunately, adult rates in the United States are now at an all-time low—23%—but rates are climbing for young people.
Although tobacco use constitutes the most serious common medical problem, it is undertreated. Over 70% of smokers see a physician each year, but only 20% of them receive any medical quitting advice or assistance. (Persons whose physicians advise them to quit are 1.6 times as likely to attempt quitting.) About 4% of smokers are able to quit each year., pancreas, kidney. A system should be implemented to identify smokers, and advice to quit should be tailored to the patient’s level of readiness to change. Pharmacotherapy to reduce cigarette consumption is ineffective in smokers who are unwilling or not ready to quit. Conversely, all patients trying to quit should be offered pharmacotherapy except those with medical contraindications, women who are pregnant or breastfeeding, and adolescents.
Several pharmacologic therapies have been shown to be effective in promoting cessation. Nicotine replacement therapy doubles the chance of successful quitting. The nicotine patch, gum, and lozenges are available over-the-counter, and nicotine nasal spray and inhalers by prescription. When the spray is combined with the patch, cessation rates are substantially higher. The sustained-release antidepressant drug bupropion (150–300 mg/d orally) is an effective smoking cessation agent and is associated with minimal weight gain, although seizures are a contraindication. It acts by boosting brain levels of dopamine and norepinephrine, mimicking the effect of nicotine. Bupropion, either alone or in combination with a nicotine patch, has been shown to produce significantly higher abstinence rates (30–35% at 1 year) than either a patch alone or placebo. Weight gain was less in the combined program.
More recently, varenicline, a partial nicotinic acetylcholine-receptor agonist, has shown promise as an effective agent. Weight gain occurs in most patients (80%) following smoking cessation. For many it averages 2 kg, but for others (10–15%) major weight gain—over 13 kg—may occur. Clinicians should not show disapproval of patients who have not stopped smoking or who are not ready to make a quit attempt. Thoughtful advice that emphasizes the benefits of cessation and recognizes common barriers to success can increase motivation to quit and quit rates. An intercurrent illness such as acute bronchitis or acute myocardial infarction may motivate even the most addicted smoker to quit. Individualized or group counseling is very cost effective, even more so than treating hypertension. Smokking cessation counseling by telephone (“quitlines”) has proved effective. An additional strategy is to recommend that any smoking take place out of doors to limit the effects of passive smoke on housemates and coworkers. This can lead to smoking reduction and quitting. The clinician’s role in smoking cessation is summarized in. Public policies, including higher cigarette taxes and more restrictive public smoking laws, have also been shown to encourage cessation.
Prevention of Infectious Disease
Preventive medicine can be categorized as primary, secondary, or tertiary. Primary prevention aims to remove or reduce disease risk factors (eg, immunization, giving up or not starting smoking). Secondary prevention techniques promote early detection of disease or precursor states (eg, routine cervical Papanicolaou screening to detect carcinoma or dysplasia of the cervix). Tertiary prevention measures are aimed at limiting the impact of established disease (eg, partial mastectomy and radiation therapy to remove and control localized breast cancer). Table 1–1 gives data for deaths from preventable causes in the United States. Table 1–2 compares recommendations for periodic health examinations as developed by the United States Preventive Services Task Force, the American College of Physicians, and the Canadian Task Force on the Periodic Health Examination. Despite emerging con ensus on many of the services, controversy persists for others.
Many effective preventive services are underutilized. In 2006, the National Commission on Prevention Priorities ranked clinical preventive service recommendations up to December 2004. The three highest-ranking services were discussing aspirin use with high-risk adults, tobacco-use screening and brief interventions, and immunizing children. Other high-ranking services with data indicating low current utilization rates (< 50%) included screening adults aged 50 and older for colorectal cancer, immunizing adults aged 65 and older against pneumococcal disease, and screening young women for Chlamydia sures—especially immunization, improved sanitation, and better nutrition.
Immunization remains the best means of preventing many infectious diseases. In the United States, childhood immunization has resulted in near elimination of measles, mumps, rubella, poliomyelitis, diphtheria, pertussis, and tetanus. Haemophilus influenzae type b invasive disease has been reduced by more than 95% since the introduction of the first conjugate vaccines. However, substantial vaccine-preventable morbidity and mortality continue to occur among adults from vaccine-preventable diseases, such as hepatitis A, hepatitis B, influenza, and pneumococcal infections. For example, in adults in the United States, there are an estimated 50,000–70,000 deaths annually from influenza, hepatitis B, and invasive pneumococcal disease. In 2002, only about 65% of elderly persons reported receiving influenza and pneumococcal vaccines. It has been documented that annual influenza immunization with inactivated vaccine (administered intramuscularly) prevents cardiovascular morbidity and all-cause mortality in persons with coronary and other atherosclerotic vascular disease. However, immunization with live, attenuated vaccine (administered intranasally) is contraindicated for such persons.
The American College of Physicians recommends that clinicians should review each adult’s immunization status at age 50; assess risk factors that would indicate a need for pneumococcal vaccination and annual influenza immunizations; reimmunize at age 65 those who received an
immunization against pneumococcus more than 6 years before; ensure that all adults have completed a primary diphtheria-tetanus immunization series, and administer a single booster at age 50; and assess the postvaccination serologic response to hepatitis B vaccination in all recipients who have ongoing risks of exposure to blood or body fluids (eg, sharp injuries, blood splashes). Recently, strategies have also been proposed to improve influenza, pneumococcal polysaccharide, and hepatitis B targeted vaccination; in other words, improve coverage among those adults aged 65 years or younger who are at high risk for exposure or disease. Strategies to enhance vaccinations in general include increasing community demand for vaccinations; enhancing access to vaccination services; and provider- or system-based interventions, such as reminder systems. Clinicians can substantially improve immunization rates by use of standing orders and algorithms, expanded nurse decision-making, patient education and incentives, and partnership with community pharmacies. Increasing reports of pertussis among US adolescents, adults, and their infant contacts have stimulated vaccine development for older age groups. A safe and effective tetanus-diphtheria 5-component acellular pertussis vaccine (Tdap) is now available for use in adolescents and adults. On October 26, 2005, the Advisory Committee on Immunization Practices (ACIP) recommended routine use of a single dose of Tdap for adults
aged 19–64 years to replace the next booster dose of tetanus and diphtheria toxoids vaccine (Td). The ACIP also recommended Tdap for adults who have close contact with infants younger than 12 months, for pregnant women, and women who are planning a pregnancy.
Recommended immunization schedules for children and adolescents and adults are set forth in Tables 30–12 and 30–13. Thimerosal-free hepatitis B vaccination is now available for newborns and infants. Human papillomavirus (HPV) virus-like particle (VLP) vaccines have demonstrated effectiveness in preventing persistent HPV infections, and thus may impact the rate of cervical intraepithelial neoplasia II–III. Results from one randomized controlled trial of HPV16 L1 VLP vaccine showed that it provided high-level protection against persistent HPV16 infection and HPV16-related CIN II–III for at least 3.5 years after immunization.
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