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Feeling bad and risk of stroke

Isles, Chris

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The suggestion that ‘feeling bad’ may contribute to the risk of stroke is not something with which most readers of this journal are likely to feel comfortable or even familiar, but this is exactly the conclusion drawn by a group of public health researchers from Sweden in a study of a large number of subjects who had participated in a health survey [1], as reported in this issue of the journal. Four hundred and seventy-three individuals had a definite first ever stroke between 1985 and 2000. Each was matched with two controls for age, sex and residence. The measure of self-rated health in this and other studies was the response to the question ‘In general, would you say that your health is excellent, very good, good, fair or poor'. The main exclusions were individuals who had a diagnosis of myocardial infarction or cancer in the 5 years preceding their stroke, which makes it unlikely that poor self-rated health was a consequence of these particular comorbidities.

The main findings of the survey by Emmelin et al. [1] were that individuals with two or more biological risk factors who rated their own health as ‘not good’ were much more likely to have a stroke. The authors went on to suggest that their findings were gender specific and education sensitive. Men appeared to be at greater risk of stroke than women, as were well-educated people of both sexes, if they rated their health as ‘not good'. They concluded that self-rated health may have a causal role in 20% of stroke cases in Northern Sweden, an impact similar to that of hypertension and smoking [1].

A previous study by the same group explored the relation between biomedical risk factors, perceived health and the development of myocardial infarction in a series of 78 myocardial infarction patients drawn from the same population survey and showed that perceived ill health amplified the risk of myocardial infarction by a factor of 5 when three biomedical risk factors were present [2]. Similar findings have been reported by others, both for stroke [3] and for coronary heart disease (CHD) [4]. We also know from a limited number of longitudinal studies that both stroke and CHD lead to loss of self-rated health [5,6] and that self-rated health predicts outcome in patients with these conditions [7,8].

These studies raise a number of interesting questions regarding the meaning and implication of self-rated health, particularly for those of us who feel more at ease with the biomedical model of stroke risk and outcome. If, as seems likely, self-rated health is a global measure of both physical and psychological health then what exactly is it measuring? Illness related variables such as chronic disease, disability and pain, together with lifestyle factors including smoking, alcohol intake and physical inactivity, may all contribute to the physical component of self-rated health [9], while mastery, chronic distress, self-esteem, social support [9] and depression [10] have been shown to be important psychological factors.

The next question is whether self-rated health is an independent predictor of risk or a proxy for one of its determinants. There is good evidence, as summarized in a review by Goldstein [11], that lifestyle factors such as smoking, alcohol intake and physical inactivity, all of which may cause ill health, can increase the risk of stroke. We also know that depression is significantly associated with stroke incidence [12] and that negative attitudes to health predict worse long-term survival in stroke patients [13]. Both depression and negative attitudes to health appear likely to determine whether a person feels good or not good, and might therefore be the drivers of the association between self-rated health, stroke incidence and outcome.

None of these issues were explored fully in the study by Emmelin et al. [1], although a survey of 2885 individuals who had angiographically proven CHD may provide some answers [8]. Those who rated their health as poor had a significantly greater risk of CHD-related mortality than those who rated their health as very good (odds ratio 3.6) after adjusting for all available mortality risk factors. These included socio-demographic variables, physical comorbidities, CHD disease severity, health-related quality of life, measures of social support and indices of depression. Thus in patients with pre-existing CHD, self-rated health would appear to be an independent risk factor [8].

The possibility that the response to a question as simple as ‘Would you say your health is excellent, very good, good, fair or poor’ may predict stroke risk and provide information over and above that obtained by conventional risk factors is at the very least intriguing. The fact that this risk appears to be amplified in those individuals with the most conventional risk factors is certainly worthy of further attention. Clearly, there is much to be done here [14]. In particular, we need to establish the determinants of self-rated health and confirm that its predictive power is independent of other risk factors. We also need to investigate whether self-rated health is a stable characteristic or whether it changes, and we need to know whether we can alter it and, consequently, whether this improves outcome.

Meanwhile what, if any, advice can be given to patients as a result of the study by Emmelin et al. [1] and others like it? In a recent review of the determinants of successful ageing, the definition of which included the absence of death or disability before age 80 years, seven protective factors were found that were under at least some personal control. These were an absence of alcohol abuse, not smoking, being physically active, an acceptable body mass index, marital stability, coping mechanisms and a good education [15]. It is likely that each of these could contribute to an estimate of self-rated health, suggesting avenues of intervention for patients whose self-rated health is described as poor. Consequently, when we review our hypertensive patients, we might ask them to rate their own health while we are checking their blood pressure and take more notice if they say they are ‘feeling bad'.

Acknowledgements

I should like to thank Lesley Howells, Lorna McArthur, Bob Lewin and Martin Dennis for their helpful comments.

References

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© 2003 Lippincott Williams & Wilkins, Inc.