Introduction

"Lord, grant me the serenity to accept the things I cannot change, the courage to change the things that can be changed, and the wisdom to know the difference."

Hundreds of years ago the occurrence of disease as one got older was accepted as inevitable. As we enter the 21st century it is pleasing to note that, with some exceptions, the present-day means of treating disease are usually quite successful. More and more attention is now being directed towards forestalling disease in the first place. We know that ailments rarely strikes out of the blue - there are usually a number of warning signs, and, if we look earlier in the process, a number of risk factors that indicate how likely one is to be harmed.

Fixed Risk Factors

Some diseases are predetermined from birth - these are hereditary or genetic diseases. It may be certain that the afflicted person will acquire the disease (e.g. hemophilia), or merely have a tendency towards getting it (e.g. cancer of the breast). Some diseases affect one sex more than the other - exclusively (e.g. enlarged prostate) or predominantly (e.g. osteoporosis in women). Most diseases are more likely to occur as we get older. One can say that genetic make-up, gender and age are fixed, or immutable, risk factors - things that we can do nothing about, at least at present. (Practical applications of genetic engineering are on the horizon, which may allow some hereditary disorders to be eliminated in "treated" individuals.)

If someone is at risk genetically for a given disease (e.g. diabetes in a Native American), it is sensible to work on any changeable risk factors for that disease, to try and balance out the ethnic risk.

Changeable Risk Factors

It is generally accepted that sufficient exercise, not smoking, and a low-fat diet will go a long way to staving off heart attacks at an early age. But these lifestyle adjustments carry other health benefits. Regular physical exercise lowers the risk of developing adult-onset (type 2) diabetes and high blood pressure. Not smoking lowers the risk of lung cancer, as well as other cancers, dramatically. In other words, addressing one risk factor will improve the outlook for a number of serious end results, while in order to forestall one undesired end result it may be necessary to address several risk factors.

Clearly there are intermediate steps that occur before the full disease appears. These often "silent" changes can be picked up by medical or lab exams. In fact, they also represent risk factors that can at times be addressed by lifestyle changes, but more often they require medication (e.g. blood pressure drugs, cholesterol-lowering drugs). Sometimes the disease process can be arrested or controlled at a stage before the final damage is done.

For each disease, or for each silent change predicting a disease, patients and their physicians should search for possible modifiable risk factors - new ones are being discovered every day. It should be realized that there may be synergy between risk factors for a given disease - i.e. if two risk factors are present, the actual risk is greater than the two risks added together.

How are Risk Factors established?

Historically, risk factors were suspected based on differences in the frequencies of diseases in different populations. Statistical "proof" of an association between a particular factor and the occurrence of a disease depends on what are known as epidemiology studies. The frequency of the disease is measured in two or more groups of subjects that have different frequencies of the factor being examined. The groups can be made up of two "cohorts" of subjects who are followed for a period of time, or the afflicted group together with a selected "case-control" group, consisting of one or more otherwise normal subjects for each diseased subject, matched closely for age, sex, etc.

Analyses allow calculation of the risk, which is usually expressed as a "Risk Ratio", a "Relative Risk", an "Odds Ratio", or a "Hazard Ratio". Often sophisticated analyses are necessary, to neutralize the effects of one possible risk factor on another - these are termed multivariate analyses. Sometimes graphs are prepared which display the percentage of people with the disease (or death) in the groups being compared over a period of time - these are called Kaplan-Meier survival curves.

If the results of such studies show a statistically significant increased relative risk, they can be translated into more understandable terms as, such as "in the presence of . . . . (a given risk factor) there is a 3-fold increase in the likelihood of developing the disease".

Tackling Risk Factors

For practical purposes, we can consider two ways to tackle changeable risk factors:

• Lifestyle Changes
• Medical Intervention

Lifestyle changes include diet, physical activity (endurance/aerobic and strength/resistance exercises), and overcoming an addiction (eating, smoking, excess alcohol, gambling, etc). The major impetus for change must come from the subjects themselves. However, help is often needed to overcome laziness, boredom and even dislike of the positive things that must be done (e.g. diet, exercise). Even more help, often involving support groups and medication, is required in resisting the temptations, or "bad friends", that sustain an addiction.

Medical Intervention often involves someone taking a drug for a long time - perhaps a lifetime - even when the person is feeling well. Family members and physicians must encourage the person with a silent risk factor, such as high blood pressure, to stick to the prescribed medication, and to attend for regular check-ups to ensure that the condition remains under control.

How is the layperson to evaluate which risk factor is sufficiently well established that he or she should adapt their lifestyle or seek appropriate medication? Risk factors have different "levels of proof", depending on the available evidence for each. For example, the evidence that a raised cholesterol level is a risk factor for a heart attack is very strong - three levels of proof have been established:

1. Epidemiological studies done in the 1950s showed an increased occurrence of heart attacks in people with raised cholesterol levels.
2. The ability to lower serum cholesterol by appropriate diet, exercise and/or drugs was shown in the 1960s-1970s.
3. In the 1980s large long-term clinical studies showed that heart attacks were less common in people who had their cholesterol levels lowered by diet, exercise or drugs.

It can be seen that over 30 years passed before the first pointer of a cause-and-effect was translated into really solid proof. In another example - the case of the role of antioxidants (e.g. vitamin C and E) in the causation of heart disease - we are just at level 1. The mechanism of their action, or indeed whether antioxidant levels in the blood can be altered, is not yet established. Results of long-term studies of the effects of antioxidant supplements are ongoing, but results are still some years away. Not surprisingly, older people are often unwilling to wait, and prefer to start taking possibly helpful preventive steps before their effectiveness is unquestionable. That is quite understandable, and presents no problem provided the remedies are safe. Unfortunately, it can take as long to demonstrate the safety of new drugs or remedies as it does to prove their effectiveness in preventing disease.

Summary

The existence of risk factors for a large number of diseases has led to a surge of interest in improving ones lifestyle in order to head off ill-health. Knowledge of which risk factors are important for a particular disease allows the most appropriate steps to be taken. Regular physical check-ups, including lab exams, will detect any "silent" risk factors, such as high blood pressure or a high cholesterol level that can be taken care of before they lead to disabling illness. Results from new epidemiology studies are being reported every day. They show that if you take charge of your lifestyle, together with help and advice from your health professionals, you may expect to prolong your period of good health into a ripe old age.

"Live better today so that you age better tomorrow"