Last update: December 27, 2019.

An ounce of prevention is worth a pound of cure

This axiom of Benjamin Franklin is still as valid as it was when Franklin proposed it in 1736. Although many use the quote when referring to health, Franklin actually was addressing fire safety.

What does mean prevention?

Prevention includes a wide range of activities ―known as “interventions”― aimed at reducing risks or threats to health. You may have heard researchers and health experts talk about three categories of prevention: primary, secondary and tertiary.


Primary prevention

Primary prevention aims to prevent disease or injury before it ever occurs.

This is done by preventing exposures to hazards that cause disease or injury, altering unhealthy or unsafe behaviours that can lead to disease or injury, and increasing resistance to disease or injury should exposure occur.

Some examples for primary prevention include:

  • Legislation and enforcement to ban or control the use of hazardous products (e.g. asbestos) or to mandate safe and healthy practices (e.g. use of seatbelts and bike helmets).
  • Education about healthy and safe habits (e.g. eating well, exercising regularly, not smoking).
  • Immunization against infectious diseases.


US Preventive Services Task Force (USPSTF) Recommendations for Primary prevention




Secondary prevention

Secondary prevention aims to reduce the impact of a disease or injury that has already occurred.

This is done by detecting and treating disease or injury as soon as possible to halt or slow its progress, encouraging personal strategies to prevent reinjury or recurrence, and implementing programs to return people to their original health and function to prevent long-term problems.

Some examples for secondary prevention include:

  • Regular exams and screening tests to detect disease in its earliest stages (e.g. blood and urine based tests or mammograms).
  • Daily, low-dose aspirins and/or diet and exercise programs to prevent further heart attacks or strokes.
  • Suitably modified work so injured or ill workers can return safely to their jobs.


Tertiary prevention

Tertiary prevention aims to soften the impact of an ongoing illness or injury that has lasting effects.

This is done by helping people manage long-term, often-complex health problems and injuries (e.g. chronic diseases, permanent impairments) in order to improve as much as possible their ability to function, their quality of life and their life expectancy.

Some examples for tertiary prevention include:

  • Cardiac or stroke rehabilitation programs, chronic disease management programs (e.g. for diabetes, arthritis, depression, etc).
  • Support groups that allow members to share strategies for living well.
  • Vocational rehabilitation programs to retrain workers for new jobs when they have recovered as much as possible.


Return On Investment (ROI) and Cost-Benefit Ratio (CBR)

Return On Investment (ROI) and Cost-Bbenefit Ratio (CBR) are two forms of economic evaluation that value the financial return, or benefits, of an intervention against the total costs of its delivery.

The CBR is the benefit divided by the cost, and the ROI is the benefit minus the cost expressed as a proportion of the cost, that is, the CBR−1.

In this way, in a systematic review to examine the ROI of public health interventions delivered in high-income countries with universal healthcare (UK, Western Europe, the USA, Canada, Japan, Australia and New Zealand), 2,957 potentially relevant titles were initially identified from PubMed, MEDLINE, Scopus, CINAHL, Cochrane, PsycInfo and AMED databases.

After excluding 2,816 papers following title or abstract review, finally 52 relevant titles published over four decades were included.

The median ROI for all public health interventions was 14.3, and the median CBR was 8.3.

In other study, aimed to determine whether changes in health risks for workers in small businesses could produce medical and productivity cost savings in a 1-year pre and post test, 10 modifiable health risks for 2,458 workers were tracked.

Risk reductions were entered into a Return On Investment (ROI) simulation model. Besides, reductions were recorded in 10 risk factors examined, including obesity (−2.0%), poor eating habits (−5.8%), poor physical activity (−6.5%), tobacco use (−1.3%), high alcohol consumption (−1.7%), high stress (−3.5%), depression (−2.3%), high blood pressure (−0.3%), high total cholesterol (−0.9%), and high blood glucose (−0.2%).

The ROI model estimated medical and productivity savings of $2.03 for every $1.00 invested, so ROI was 1.03 and CBR was 2.03.

In a similar way, when mass diphtheria immunization was introduced in Britain 40 years ago, even then roughly 600 children had to be immunized in order that one life would be saved. That means 599 immunizations were “wasted” for the one that was effective. In the same way, if all British doctors wore their car seatbelts on every journey throughout their working lives, then for one life there by saved there would be about 400 who always take that preventive precaution: 399 would have worn a seatbelt every day for 40 years without benefit to their survival. This is the kind of ratio that one has to accept in mass preventive medicine. A measure applied to many will actually benefit few.

In the same way, according to the Framingham study, men were to modify their diet in such a way as to reduce their cholesterol levels by 10%, then among men of average coronary risk about one in 50 could expect that through this preventive precaution he would avoid a heart attack (if change in a risk factor leads to commensurate reduction in risk): 49 out of 50 would eat differently every day for 40 years and perhaps get nothing from it. For the same preventive measure in a higher-risk group (those with a little hypertension and a slightly raised cholesterol concentration and smoking cigarettes), the ratio rises to one in 25.

That most do not take advantage of it, Geoffrey Rose called it the “Prevention Paradox”, although it is a logical point of view.

The “Prevention Paradox”

The “Prevention Paradox”, stated by Geoffrey Arthur Rose ―an eminent epidemiologist whose ideas have been credited with transforming the approach to strategies for improving health (he was formerly the Emeritus Professor of Epidemiology at the Department of Epidemiology, London School of Hygiene and Tropical Medicine)―, states that “a measure that brings large benefits to the community offers little to each participating individual”.

For example, a population that reduces the proportion of hypertensive patients will decrease their incidence of stroke; and the one with a small percentage of hypercholesterolemic agents will have less incidence of myocardial infarction than another one in which dyslipidemic patients abound. On the other hand, among people suffering from stroke or myocardial infarction, normotensive or normolipemic are no exception. What is valid for society is not necessarily for the individual. If a probability of X of 0.1 or 0.2 in the collective means that 10 or 20 out of 100 people have X, in the case of a specific person the event occurs or not, it does not occur in 10% or in 20% of X, because one tenth of a stroke or heart attack makes no sense.

In this sense, if we take into account the deterrent effect of assuming the inconvenience and even possible adverse effects first and expect the benefits to be received in the future, it is not surprising that it is unattractive to oneself. So fearing that the behavior of individuals does not respond to the utilitarian rationality that values optimizing population benefit, it seems easy to succumb to the temptation to skip relevant information that could make us give up, or at least doubt the convenience, of adopting the preventive measure. Of course, the probability of suffering adverse effects when exposed to preventive activities is much lower than that of benefiting from the protection they offer, but the dilemma persists because to whom it happens, it will have happened.

Why is prevention so difficult?

This is a daily question in medical practice and public health, as well as in those who formulate public policies.

Prevention was very important to increase longevity to current levels: in the twentieth century the acceleration of economic growth, best hygienic practices and the recognition of infectious diseases allowed better nutrition and better living conditions and the widespread administration of vaccines and antibiotics. The great infectious diseases that flourished in the slums of newly industrialized nations were no longer so threatening.

In 2010, non-communicable diseases caused two-thirds of deaths worldwide. This epidemiological transition increased the importance of the prevention of chronic diseases.

However, preventive approaches differ from the traditional curative approach. When the patient seeks medical attention for his symptoms, the doctor’s goal is to make the diagnosis, know the pathology that causes the disease and identify the optimal treatment for that patient. For care and cure it is not important to know how many others in the population experience a similar disease.

Obstacles for prevention


Success is invisible

This obstacle is fundamental and intrinsic to prevention. There is no way to document or prove that a person’s preventive efforts improved their health. For example, when it comes to cardiovascular prevention, it can only be presumed that the permanent effort to maintain a healthy diet, avoid a sedentary lifestyle and avoid also smoking helped prevent a myocardial infarction. On the other hand, it is possible that this person had been among the hypertensive and sedentary smokers who do not suffer a heart attack.

Statisticians and scientists can list the results that occur, such as the number of myocardial infarctions and the number of deaths. But when prevention is successful, it creates absence of events: when it works, the success of prevention is silent and invisible.

Invisibility causes problems

Due to the invisible success, some people may believe that vaccines are no longer necessary. Some diseases, such as whooping cough or measles, may seem distant, and claims about vaccination risks may sound more threatening, although there is no reliable evidence to support them. When a sufficient number of people stop vaccinating, as happened in the United Kingdom and Japan, outbreaks occur. Deaths from recent outbreaks of pertussis in California could have been avoided. When vaccination rates decrease, diseases can reappear, but when vaccines are used, their success is invisible.

Absence of spectacularity

Certain types of healing interventions are spectacular. When a child can survive thanks to a liver transplant, the child, family and medical team are excited. But does anyone think of the other child, the one who was a donor, who died in an accident because the parents did not placed him in the proper safety car seat? The tragedy that could have been prevented is not taken into account.

Remote results

People in general when they want something, they want it immediately. Prevention often means doing something every day and the reward is not only statistical and invisible, but also remote. Most people prefer tangible rewards here and now.

In summary, in chronic diseases the clinician’s first contact with the patient comes late in the natural history of the disease, usually after a catastrophe or major complication and when there is already much irreversible pathological change. Indeed, in some 20% of at all cardiovascular issues, the first recognized occurrence being sudden death. In this way, it follows inexorably that prevention is essential, and that’s why we emphasize the Cx checkups.

The success of prevention is silent and invisible


Bibliographic references


Scientific publications

  1. Goetzel, R. Z., Tabrizi, M., Henke, R. M., Benevent, R., Brockbank, C. v. S., Stinson, K., … Newman, L. S. (2014). Estimating the Return on Investment From a Health Risk Management Program Offered to Small Colorado-Based Employers. Journal of Occupational and Environmental Medicine, 56(5), 554–560. doi:10.1097/jom.0000000000000152
  2. Maeng, D. D., Geng, Z., Marshall, W. M., Hess, A. L., & Tomcavage, J. F. (2018). An Analysis of a Biometric Screening and Premium Incentive-Based Employee Wellness Program: Enrollment Patterns, Cost, and Outcome. Population Health Management, 21(4), 303–308. doi:10.1089/pop.2017.0110
  3. Masters, R., Anwar, E., Collins, B., Cookson, R., & Capewell, S. (2017). Return on investment of public health interventions: a systematic review. Journal of Epidemiology and Community Health, 71(8), 827–834. doi:10.1136/jech-2016-208141
  4. Norman A. H., Hunter D. J., Russell A. J.. Linking high-risk preventive strategy to biomedical-industry market: implications for public health. Saude soc. 2017 Sep; 26( 3 ): 638-650. doi:10.1590/s0104-12902017172682
  5. Rose G., Sick individuals and sick populations, International Journal of Epidemiology, Volume 30, Issue 3, June 2001, Pages 427–432. doi:10.1093/ije/30.3.427

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