Friday, September 01, 2006

Health Belief Models

The Health Belief Model (HBM) was originally developed by Rosenstock (1966). According to the model (see above image), a person's readiness to take a h action is determined by four main factors:

• the perceived susceptibility of the disease;

• the perceived severity or seriousness of the disease;

• the perceived benefits of the health action;

• the perceived barriers to performing the action.

More recent revisions of the theory (Becker and Rosenstock, 1984) have also included three further factors in the HBM. These supplementary factors are demographic variables, psychosocial variables and structural variables, in particular knowledge of the disease and contact with the disease. More recently 'cues to action' has been added as an additional explanatory variable (Figure 10.1) This proliferation of variables led Oliver and Berger (1979) to describe the HBM as 'more a collection of variables than a formal theory or model' (p. 113).

The model works like this; the likelihood of me altering my health lifetsyle, lets say to stop smoking, is affected by my reasoning about such a change. I will need to be aware of how susceptible I am to illness coming from smoking and how severe this could be. These factors are more than likely to be effected by demographic variables, such as my age, sex and where I live. Then I weigh up the benefits but also the barriers to me stopping smoking. This will be affected by psychological variables, such as my personality, peer group pressure, etc. Finally having done all of this I will still need some kind of cue to action to get me started on any change to my health lifestyle (cutting down or quiting smoking).

Here is an example; I want to stop smoking because I could get lung cancer (susceptible) and this would be very bad (severity), given my age (33) and that I am male this is now a very real risk. The benefits are that I get to live a long and healthy life but the barriers are that I have smoked for so long that I am addicted. However I believe I can beat my addiction and I have the support of my family (psychological and social factors). Now all I need is a cue to doing something about it, this may be not being able to cycle as fast as my son, or that my wife and son complain that I cough alot in the morning. These spur me on to quitting smoking!

Here is a different example; I want to stop smoking because I could get lung cancer (susceptible) and this would be very bad (severity), but given my age (15) and that I am female I don't see this as a great risk (only OLD people get cancer from smoking, don't they?). The benefits would be that I get to live a long and healthy life but the barriers are that if I stop smoking I may put on weight and not seem so mature. Given the fact that I am currently highly neurotic about my weight and appearance and that I must be seen as mature and most of my fiends smoke, means I am unlikely to view the long term benefits of quitting smoking in a favourable way. I do not seem to be getting ill or unfit because I smoke, nor does anyone complain to me about smoking (except my boyfriend, but I can ignore him), so there is no cue for action. Thus I choose to continue smoking even though I do know that on some levels I should not do so.

Research evidence does lend support to this model, though usually only parts of it rather than the whole thing. For example, The Canadian Health Promotion Survey found that two-thirds of Canadians believed that exercise would benefit their health (Canada mess Survey, 1984). Further, it was apparent that those who reported increasing their exercise level did so mainly because of their increased knowledge of the risks of remaining sedentary. The Canada Fitness Survey found that the most frequently cited barriers for lack of participation in exercise were lack of time, injury, illness, poor weather and inconvenience. Lee (1993) suggested that the identification of these external barriers may act as a means of avoiding personal responsibility for lack of exercise.

Theory of Reasoned Action

The theorv of reasoned action (TRA) was developed by Ajzen and Fishbein (1980) and argues that intention is the best predictor of behavior. An intention toward a behavior is influenced by our attitude toward that behavior. This attitude is influenced by the strength of belief that the behavior will result in a certain outcome and the evaluation of the outcome. Say, you intend to start exercising to lose weight. You will have a strong intention to exercise, if you believe exercise (behavior) will result in losing weight (outcome) and losing weight is important to you (evaluation). Intention is also determined by what we believe other people think about our ability to obtain a certain outcome and how they evaluate that outcome. This is called the subjective norm. For example, if your family and friends think it unlikely that you can stick with an exercise program or that weight lose for you is not desirable, your intention to exercise may be weakened. It depends, in part, on how much you care about what they think. Intention, then, is determined by the individual's attitude toward the behavior and subjective norms.

This theory was then further altered by Ajzen to include and extra dimension; the individuals belief that they can control their behaviour enough to allow any change to occur. With this addition the model became known as the Theory of Planned Behaviour.

Theory of Planned Behaviour

Here is an example of how the model works: If applied to alcohol consumption, the TPB would make the following predictions; if an individual believed that reducing their alcohol intake ould make their life more productive and be beneficial to their health (attitude to the behaviour) and believed that the important people in their life wanted them to cut down (subjective norm), and in addition believed that they were capable of drinking less alcohol due to their past behaviour id evaluation of internal and external control factors (high behavioural and evaluation of internal and external control factors (high behavioural control), then this would predict high intentions to reduce alcohol intake (behavioural intentions).

The theory of planned behaviour has been used to assess a variety of health-related behaviours. For example, Brubaker and Wickersham (1990) examined the role of the theory's different components in predicting testicular self-examination and reported that attitude towards the behaviour, subjective norm and behavioural control correlated with the intention to perform the behaviour.

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