One of the most well-known quotes about preventionist from Benjamin Franklin, one of the founding fathers of the United States of America. He said, "An ounce of prevention is worth a pound of cure." Franklin was actually talking about fire safety in Philadelphia. But this idea that prevention is better than cure applies as much to help as anything else, and perhaps has the intuitive nature of this statement that makes prevention one of the more straightforward principles of public health practice. In terms of other arguments for prevention, well there's a moral argument that we should avert disease because it's the right thing to do, and then there's a frequently quoted economic argument that spending money now will save you money down the line. So that's simple, we should do more prevention, and yet we don't. On a personal level every one of us every day makes unhealthy choices, and then health systems prevention funding is frequently looted to make up for shortfalls in funding acute front line responsive services. So why is that? Well, while prevention isn't intuitively and morally the right thing to do, it can be problematic. Firstly, prevention is difficult. Secondly, the benefits you accrue in the future and the cost is immediate. Thirdly because you're preventing something from happening, in practice it's very difficult to know whether what you did actually worked. Most of us can't count things that didn't happen. Put together it means that calculating return on investment what we call ROI is really difficult. Prevention costs money and when your health system is under pressure prevention funding is an easy area to raid. In public health we talked about three types of prevention; primary, secondary and tertiary. Primary prevention is the prevention of disease through the control of exposure to risk factors. An example could be a population-wide strategy to reduce salt intake in an effort to reduce the prevalence of hypertension. Essentially we're doing something to prevent our population from developing hypertension the disease. Secondary prevention is the application of available measures to detect early departures from health and to introduce appropriate treatment and interventions. What we mean by that is it is not slowing the impact of a disease that has already taken hold. An example could be blood-pressure tablets, what we term anti-hypertensive pharmacotherapy, for patients who've been diagnosed with hypertension. That'll seem straightforward. Primary prevention is about preventing disease from starting and secondary prevention is about slowing the onset of disease. Well, let me add a little complication to this. Hypertension is a disease in itself, yet it's also a risk factor for a range of other diseases such as stroke or ischemic heart disease. On this basis anti-hypertensive pharmacotherapy while tended to be secondary prevention for hypertension could also be correctly categorized as primary prevention for stroke. Now in the real world this distinction is not that important, but I want to draw your attention to it because you need to be clear in your own mind what causal pathway you're seeking to alter, and indeed be able to answer the question when your clinical colleagues turn to you and inquire whether what they're doing is indeed primary or secondary prevention. So this brings us to tertiary prevention. Tertiary prevention is the application of measures to reduce or eliminate long-term impairments and disability, minimizing suffering caused by existing departures from good health and to promote the patient's adjustment to that condition. What I'll say here is that there's another layer of opportunity that we can potentially badge as prevention which leads to mitigate against the impact of disease. This is often about helping people manage their condition and improve their quality of life, living with that condition. An example could be support groups that allow members to share coping strategies with environmental alterations that enables someone to retain their independence. Tertiary prevention is the least specific of the three types, and in my experience it's used quite vaguely. I'm actually not sure myself it's a terribly helpful term. I like to think of it as synonymous with the word mitigation, yet when funding bids come round for prevention the idea of tertiary prevention can be helpful in marshaling the money to do something that you already had your eye on. So why do we make these distinctions? Well, it's conceptually helpful to separate primary from secondary prevention. Primary prevention is more commonly owned by public health. Secondary prevention can more often be the preserve of more traditional health care services. But it's really important that when you speak to politicians and senior decision-makers that you're clear on what they mean by prevention. They may have very specific ideas and it's also possible they've not given it much thought. But clearly the impact, logistics and value of prevention depends on what you're really trying to achieve, and that's why knowing the difference between these types of prevention is important in practice.
