Levels of Prevention
Preventive healthcare strategies are typically described as taking place at the primary, secondary, and tertiary prevention levels. In the 1940s, Hugh R. Leavell and E. Gurney Clark coined the term primary prevention. They worked at the Harvard and Columbia University Schools of Public Health, respectively, and later expanded the levels to include secondary and tertiary prevention.[9] Goldston (1987) notes that these levels might be better described as "prevention, treatment, and rehabilitation"[9] though the terms primary, secondary, and tertiary prevention are still commonly in use today.
| Level |
Definition |
| Primary prevention |
Methods to avoid occurrence of disease either through eliminating disease agents or increasing resistance to disease.[1] Examples include immunization against disease, maintaining a healthy diet and exercise regimen, and avoiding smoking.[10] |
| Secondary prevention |
Methods to detect and address an existing disease prior to the appearance of symptoms.[1] Examples include treatment of hypertension (a risk factor for many cardiovascular diseases), cancer screenings [10] |
| Tertiary prevention |
Methods to reduce negative impact of symptomatic disease, such as disability or death, through rehabilitation and treatment.[1] Examples include surgical procedures that halt the spread or progression of disease [1] |
Primary Prevention
Primary prevention consists of "health promotion" and "specific protection."[1] Health promotion activities are non-clinical life choices, for example, eating nutritious meals and exercising daily, that both prevent disease and create a sense of overall well-being.[1][2] Health-promotional activities do not target a specific disease or condition but rather promote health and well-being on a very general level.[2] On the other hand, specific protection targets a type or group of diseases and complements the goals of health promotion.[1] In the case of a sexually transmitted disease such as syphilis health promotion activities would include avoiding microorganisms by maintaining personal hygiene, routine check-up appointments with the doctor, general sex education, etc. whereas specific protective measures would be using prophylaxis (such as condoms) during sex and avoiding sexual promiscuity.[2]
Scientific advancements in genetics have significantly contributed to the knowledge of hereditary diseases and have facilitated great progress in specific protective measures in individuals who are carriers of a disease gene or have an increased predisposition to a specific disease. Genetic testing has allowed physicians to make quicker and more accurate diagnoses and has allowed for tailored treatments or personalized medicine.[2] Similarly, specific protective measures such as water purification, sewage treatment, and the development of personal hygienic routines (such as regular hand-washing) became mainstream upon the discovery of infectious disease agents such as bacteria. These discoveries have been instrumental in decreasing the rates of communicable diseases that are often spread in unsanitary conditions.[2]
Secondary Prevention
Secondary prevention deals with latent diseases and attempts to prevent asymptomatic disease from progressing to symptomatic disease.[1] Certain diseases can be classified as primary or secondary, depending on definitions of what constitutes a disease, but in general, primary prevention addresses the root cause of a disease or injury[1] whereas secondary prevention aims to detect and treat a disease early on.[11] Secondary prevention consists of "early diagnosis and prompt treatment" to contain the disease and prevent its spread to other individuals, and "disability limitation" to prevent potential future complications and disabilities from the disease.[2] For example, early diagnosis and prompt treatment for a syphilis patient would include a course of antibiotics to destroy the pathogen and screening and treatment of any infants born to syphilitic mothers. Disability limitation for syphilitic patients includes continued check-ups on the heart, cerebrospinal fluid, and central nervous system of patients to curb any damaging effects such as blindness or paralysis.[2]
Tertiary Prevention
Finally, tertiary prevention attempts to reduce the damage caused by symptomatic disease by focusing on mental, physical, and social rehabilitation. Unlike secondary prevention, which aims to prevent disability, the objective of tertiary prevention is to maximize the remaining capabilities and functions of an already disabled patient.[2] Goals of tertiary prevention include: preventing pain and damage, halting progression and complications from disease, and restoring the health and functions of the individuals affected by disease.[11] For syphilitic patients, rehabilitation includes measures to prevent complete disability from the disease, such as implementing work-place adjustments for the blind and paralyzed or providing counseling to restore normal daily functions to the greatest extent possible.[2]
Leading causes of preventable death
United States
The leading cause of death in the United States was tobacco. However, poor diet and lack of exercise may soon surpass tobacco as a leading cause of death. These behaviors are modifiable and public health and prevention efforts could make a difference to reduce these deaths.[4]
Worldwide
The leading causes of preventable death worldwide share similar trends to the United States. There are a few differences between the two, such as malnutrition, pollution, and unsafe sanitation, that reflect health disparities between the developing and developed world.[12]
In 2010, 7.6 million children died before reaching the age of 5. While this is a decrease from 9.6 million in the year 2000,[13] it is still far from the fourth Millennium Development Goal to decrease child mortality by two-thirds by the year 2015.[14] Of these deaths, about 64% were due to infection (including diarrhea, pneumonia, and malaria).[13] About 40% of these deaths occurred in neonates (children ages 1-28 days) due to pre-term birth complications.[14] The highest number of child deaths occurred in Africa and Southeast Asia.[13]In Africa, almost no progress has been made in reducing neonatal death since 1990.[14] India, Nigeria, Democratic Republic of the Congo, Pakistan, and China contributed to almost 50% of global child deaths in 2010. Targeting efforts in these countries is essential to reducing the global child death rate.[13]
Child mortality is caused by a variety of factors including poverty, environmental hazards, and lack of maternal education.[15] The World Health Organization created a list of interventions in the following table that were judged economically and operationally "feasible," based on the healthcare resources and infrastructure in 42 nations that contribute to 90% of all infant and child deaths. The table indicates how many infant and child deaths could have been prevented in the year 2000, assuming universal healthcare coverage.[15]
Preventive Methods for Different Diseases
Obesity
Obesity is a major risk factor for a wide variety of conditions including cardiovascular diseases, hypertension, certain cancers, and type 2 diabetes. In order to prevent obesity, it is recommended that individuals adhere to a consistent exercise regimen as well as a nutritious and balanced diet. A healthy individual should aim for acquiring 10% of their energy from proteins, 15-20% from fat, and over 50% from complex carbohydrates, while avoiding alcohol as well as foods high in fat, salt, and sugar. Sedentary adults should aim for at least half an hour of moderate-level daily physical activity and eventually increase to include at least 20 minutes of intense exercise, three times a week.[16]
Cancer
In recent years, cancer has become a global problem. Low and middle income countries share a majority of the cancer burden largely due to exposure to carcinogens resulting from industrialization and globalization.[17] However, primary prevention of cancer and knowledge of cancer risk factors can reduce over one third of all cancer cases. Primary prevention of cancer can also prevent other diseases, both communicable and non-communicable, that share common risk factors with cancer.[17]
Lung cancer is the leading cause of cancer-related deaths in the United States and Europe and is a major cause of death in other countries.[18] Tobacco is an environmental carcinogen and the major underlying cause of lung cancer.[18] Between 25% and 40% of all cancer deaths and about 90% of lung cancer cases are associated with tobacco use. Other carcinogens include asbestos and radioactive materials.[19] Both smoking and second-hand exposure from other smokers can lead to lung cancer and eventually death.[18] Therefore, prevention of tobacco use is paramount to prevention of lung cancer.
Individual, community, and state-wide interventions can prevent or cease tobacco use. 90% of adults in the US who have ever smoked did so prior to the age of 20. In-school prevention/educational programs, as well as counseling resources, can help prevent and cease adolescent smoking.[19] Other cessation techniques include group support programs, nicotine replacement therapy (NRT), hypnosis, and self-motivated behavioral change. Studies have shown long term success rates (>1 year) of 20% for hypnosis and 10%-20% for group therapy.[19]
Cancer screening programs serve as effective sources of secondary prevention. The Mayo Clinic, Johns Hopkins, and Memorial Sloan-Kettering hospitals conducted annual x-ray screenings and sputum cytology tests and found that lung cancer was detected at higher rates, earlier stages, and had more favorable treatment outcomes, which supports widespread investment in such programs.[19]
Legislation can also have an impact on smoking prevention and cessation. In 1992, Massachusetts (United States) voters passed a bill adding an extra 25 cent tax to each pack of cigarettes, despite intense lobbying and a $7.3 million spent by the tobacco industry to oppose this bill. Tax revenue goes toward tobacco education and control programs and has led to a decline of tobacco use in the state.[20]
Lung cancer and tobacco smoking are making an increasing impact worldwide, especially in China. China is responsible for about one-third of the global consumption and production of tobacco products.[21]Tobacco control policies have been ineffective as China is home to 350 million regular smokers and 750 million passive smokers and the annual death toll is over 1 million.[21] Recommended actions to reduce tobacco use include: decreasing tobacco supply, increasing tobacco taxes, widespread educational campaigns, decreasing advertising from the tobacco industry, and increasing tobacco cessation support resources.[21] In Wuhan, China, a 1998 school-based program, implemented an anti-tobacco curriculum for adolescents and reduced the number of regular smokers, though it did not significantly decrease the number of adolescents who initiated smoking. This program was therefore effective in secondary but not primary prevention and shows that school-based programs have the potential to reduce tobacco use.[22]
Skin Cancer
Skin cancer is the most common cancer in the United States.[23] The most lethal form of skin cancer, melanoma, leads to over 50,000 annual deaths in the United States.[23] Childhood prevention is particularly important because a significant portion of ultraviolet radiation exposure from the sun occurs during childhood and adolescence and can subsequently lead to skin cancer in adulthood. Furthermore, childhood prevention can lead to the development of healthy habits that continue to prevent cancer for a lifetime.[23]
The Centers for Disease Control and Prevention (CDC) recommends several primary prevention methods including: limiting sun exposure between 10 AM and 4 PM, when the sun is strongest, wearing tighter-weave natural cotton clothing, wide-brim hats, and sunglasses as protective covers, using sunscreens that protect against both UV-A and UV-B rays, and avoiding tanning salons.[23] Sunscreen should be reapplied after sweating, exposure to water (through swimming for example) or after several hours of sun exposure.[23] Since skin cancer is very preventable, the CDC recommends school-level prevention programs including preventive curricula, family involvement, participation and support from the school's health services, and partnership with community, state, and national agencies and organizations to keep children away from excessive UV radiation exposure.[23]
Most skin cancer and sun protection data comes from Australia and the United States.[24] An international study reported that Australians tended to demonstrate higher knowledge of sun protection and skin cancer knowledge, compared to other countries.[24] Of children, adolescents, and adults, sunscreen was the most commonly used skin protection. However, many adolescents purposely used sunscreen with a low sun protection factor (SPF)in order to get a tan.[24] Various Australian studies have shown that many adults failed to use sunscreen correctly; many applied sunscreen well after their initial sun exposure and/or failed to reapply when necessary.[25][26][27] A 2002 case-control study in Brazil showed that only 3% of case participants and 11% of control participants used sunscreen with SPF >15.[28]
Cervical Cancer
Cervical cancer ranks among the top three most common cancers among women in Latin America, sub-Saharan Africa, and parts of Asia. Cervical cytology screening aims to detect abnormal lesions in the cervix so that women can undergo treatment prior to the development of cancer. Given that high quality screening and follow-up care has been shown to reduce cervical cancer rates by up to 80%, most developed countries now encourage sexually active women to undergo a pap test every 3–5 years. Finland and Iceland have developed effective organized programs with routine monitoring and have managed to significantly reduce cervical cancer mortality while using fewer resources than unorganized, opportunistic programs such as those in the United States or Canada.[29]
In developing nations in Latin America, such as Chile, Colombia, Costa Rica, and Cuba, both public and privately organized programs have offered women routine cytological screening since the 1970s. However, these efforts have not resulted in a significant change in cervical cancer incidence or mortality in these nations. This is likely due to low quality, inefficient testing. However, Puerto Rico, which has offered early screening since the 1960s, has witnessed an almost a 50% decline in cervical cancer incidence and almost a four-fold decrease in mortality between 1950 and 1990. Brazil, Peru, India, and several high-risk nations in sub-Saharan Africa which lack organized screening programs, have a high incidence of cervical cancer.[29]
Health Disparities and Barriers to Accessing Care
Access to healthcare and preventive health services is unequal, as is the quality of care received. A study conducted by the Agency for Healthcare Research and Quality (AHRQ)revealed health disparities in the United States. In the United States, elderly adults (>65 years old)received worse care and had less access to care than their younger counterparts. The same trends are seen when comparing all racial minorities (black, Hispanic, Asian) to white patients, and low-income people to high-income people.[30] Common barriers to accessing and utilizing healthcare resources included lack of income and education, language barriers, and lack of health insurance. Minorities were less likely than whites to possess health insurance, as were individuals who completed less education. These disparities made it more difficult for the disadvantaged groups to have regular access to a primary care provider, receive immunizations, or receive other types of medical care.[30]Additionally, uninsured people tend to not seek care until their diseases progress to chronic and serious states and they are also more likely to forgo necessary tests, treatments, and filling prescription medications.[31]
These sorts of disparities and barriers exist worldwide as well. Oftentimes there are decades of gaps in life expectancy between developing and developed countries. For example, Japan has an average life expectancy that is 36 years greater than that in Malawi.[32] Low-income countries also tend to have fewer physicians than high-income countries. In Nigeria and Myanmar, there are fewer than 4 physicians per 100,000 people while Norway and Switzerland have a ratio that is ten-fold higher.[32] Common barriers worldwide include lack of availability of health services and healthcare providers in the region, great physical distance between the home and health service facilities, high transportation costs, high treatment costs, and social norms and stigma toward accessing certain health services.[33]
Effectiveness
There is no general consensus as to whether or not preventive healthcare measures are cost-effective and worth long-term investment. There are varying views on what constitutes a "good investment." Some argue that preventive health measures should save more money than they cost, when factoring in treatment costs in the absence of such measures. Others argue in favor of "good value" or conferring significant health benefits even if the measures do not save money[7][34] Furthermore, preventive health services are often described as one entity though they comprise a myriad of different services, each of which can individually lead to net costs, savings, or neither. Greater differentiation of these services is necessary to fully understand both the financial and health impacts.[7]
A 2010 study reported that in the United States, vaccinating children, cessation of smoking, daily prophylactic use of aspirin, and screening of breast and colorectal cancers had the most potential to prevent premature death.[7] Preventive health measures that resulted in savings included vaccinating children and adults, smoking cessation, daily use of aspirin, and screening for issues with alcoholism, obesity, and vision failure.[7] These authors estimated that if usage of these services in the United States increased to 90% of the population, there would be net savings of $3.7 billion, which comprised only about -0.2% of the total 2006 United States healthcare expenditure.
