The Long-Term Effect of Physical Activity on Incidence of Coronary Heart Disease - Essay Example

This paper provides a review of two journal articles: Sundquist and Johansson’s (2004) paper en d The long term effect of physical activity on incidence of coronary heart disease: a 12-year follow-up study, which was published in volume 41 of the journal Preventative Medicine, pages 219-225, and Haffner and Cassells’ (2003) paper entitled Hyperglycemia as a cardiovascular risk factor, which was published in volume 115 of the journal The American Journal of Medicine. These two papers were used in course of writing the dissertation entitled Effects of diet and lifestyle on cardiovascular disease: sifting the evidence. The review will present a summary of the main methods and findings of each of the papers, and will then look in detail at the success of the papers, in terms of the stated aims of the papers, leading to a comparison of the papers towards the end of the review. The comparison will look at such issues as the content of the paper, the research presented, the style of presentation of the results presented, and the scientific impact of the paper. Sundquist and Johansson (2004) presents a study which analyses the long-term effect of leisure-time physical activity on incident cases of coronary heart disease amongst men and women. In terms of the methods used, a random sample of men (2645) and women (2551), aged 35-74, were taken from the national population, and were interviewed in 1988, 1989 and again in 2000, in terms of finding out the risk of suffering a cardiovascular disease event of each of the participants (Sundquist and Johansson, 2004). Only people who had not been hospitalized due to cardiovascular disease in the two years prior to the start of the study were included in the study, so as not to bias the results obtained (Sundquist and Johansson, 2004). In the interviews, leisure-time physical activity was divided into four levels, according to the mode, intensity and duration of physical activity; the relationship between leisure-time physical activity and coronary heart disease was then studied through a Cox regression model, which was adjusted for gender, age, income, smoking and body mass index, as all these factors are known to contribute to coronary heart disease (Sundquist and Johansson, 2004). In terms of the results obtained from Sundquist and Johansson (2004), they found that when leisure-time physical activity increased, the risk of coronary heart disease decreased, and most interestingly, that women and men who were physically active at least twice a week had a 41% lower risk of developing coronary heart disease than those who undertook no physical activity, after adjustment for all the explanatory values. They concluded that the positive long-term effects of leisure-time physical activity on the risk of developing coronary heart disease among women and men remains, even after accounting for the other important explanatory factors, such as gender, age, income, smoking and body mass index (Sundquist and Johansson, 2004). In terms of the design and execution of the Sundquist and Johansson (2004) study, the study was well designed and well executed, in that all recommended scientific procedures were followed, in terms of the sample size of the study (i.e., a roughly equal number of men and women were included in the study, allowing for statistical analyses to be valid), the design of the interviews (which did not hold any inherent bias, in terms of ‘pointed’ questions), and the analysis of the results, which was performed – to the letter - using a well-recognized statistical analysis. The paper could easily be used by other researchers in this field, to further the research begun in this paper, and thus to develop the research conducted in this field, as the methodology, methods of analysis and the results are presented in a highly clear manner, with each of these sections being extremely easy to follow and to understand. The researchers, through their use of such clear instructions and writing demonstrate that they are fully in control of their research, in terms of having a thorough understanding of what they research, and therefore of where the basis of their research comes from and how their research fits in to the ‘bigger picture’. Usually the best scientific research, and the papers derived there from, are presented in the clearest, most concise form; Watson and Crick’s seminal paper presenting the structure of DNA is one of the sparest papers in the history of research literature; it is presented in spare, concise, easy to understand writing, yet its impact on the development of modern biology is undeniable. One minor complaint I have against the paper is that the Conclusions derived from the methodology used in, and results gained from, the research presented are not presented as well as they could be. This study has shown an extreme positive effect of physical activity on reducing the risk of cardiovascular disease, which is an extremely important finding, yet the Conclusions section of the paper reports this finding almost as a minor fact, something which they explain through the usual socio-economic explanations that are always given when talking about the rise in the incidence of cardiovascular disease (for example, a rise in the number of VCR machines per household over the period of the study, which is hypothesized, indicates a reduction in the physical activity undertaken in the household). The Conclusions section of the paper could therefore have been made more forceful, to put forward more forcefully the important results gained in this study. Haffner and Cassells (2003) present a research paper that looks at the role of hyperglycemia as a risk factor in determining the likelihood of suffering cardiovascular disease. Haffner and Cassells (2003) began their research from the point of view of knowing that patients with type 2 diabetes have a 2-4 fold increased risk of coronary heart disease than patients without the disease, and that intensive glycemic control has a modest effect on reducing cardiovascular disease episodes, suggesting that as the development of cardiovascular disease is multi-factorial, hyperglycemia is but one of many risk factors. However, it is also thought by health care professionals that the onset of diabetes often pre-dates a cardiovascular disease episode, and as such, Haffner and Cassells (2003) research was important in terms of also offering a first empirical test of this theory, in terms of potentially providing a means of controlling the onset of cardiovascular disease. Haffner and Cassells (2003) study summarizes several studies looking at this issue. On study used a sample size of 181 Swedish patients who had been admitted to a coronary care unit without having been previously diagnosed as suffering from diabetes; it was found that, however, that of these 181 patients, 35% had impaired glucose intolerance and 31% of patients were diagnosed as suffering from diabetes shortly before discharge, showing that over 60% of patients admitted to a coronary care unit without a previous diagnosis of diabetes may have had some form of diabetes (Haffner and Cassells, 2003). Another study, the Paris Prospective Study showed that patients with type 2 diabetes had a nearly 3-fold increased risk of contracting cardiovascular disease than patients without type 2 diabetes; another study, the Wisconsin Epidemiological Survey of Diabetic Retinopathy (WESDR) indicated that a 1% increase in hemoglobin level was associated with a 70% increase in the progression of retinopathy, and a 10% increase in the risk of cardiovascular disease (Haffner and Cassells, 2003). Following their survey of studies looking at the effect of diabetes on the risk of suffering cardiovascular disease, Haffner and Cassells (2003) move on to look at the relationship between hyperglycemia and coronary heart disease, arguing that several factors may explain the relatively modest effects on glycemic control on cardiovascular disease in patients with diabetes, and suggesting that one potential problem is that cardiovascular disease is multifactorial, and that, as such, hyperglycemia is only one of many cardiovascular risk factors. As such, they suggest that the link between diabetes and an elevated risk of cardiovascular disease could be spurious, especially as they point out that some studies have suggested that cardiovascular disease can appear before the onset of diabetes (Haffner and Cassells, 2003). Haffner and Cassells (2003) the move on to looking at reducing the incidence of type 2 diabetes, in terms of lifestyle changes and the use of medications such as metformin or troglitazone, suggesting that reducing the incidence of diabetes will be beneficial in reducing the risk of suffering cardiovascular disease, at least as part of a multi-faceted approach at controlling the risk of developing cardiovascular disease (i.e., as part of a holistic attempt at reducing ones risk of developing cardiovascular disease). Haffner and Cassells (2003) paper is rather unsatisfactory as a scientific research paper, presenting as it does mere summaries of the work of other researchers and research groups. It is useful that the authors felt it necessary to summarize these findings, but it would be equally easy for researchers to find the original research papers themselves, to be able to consult them in the course of their own research, as to consult this paper and then need to consult the original research, in terms of finding detailed information from them, for example. As such, the review presented in this paper is a useful exercise for lay people, and for GP’s, and other health care practitioners, for example, but in terms of the usefulness of this paper to other researchers, its use is limited. Research papers that are presented in scientific papers normally present original research, and as such, are used to further the scientific process, for example the paper of Sundquist and Johansson (2004) presents original data that suggests that increasing physical activity can decrease the risk of developing cardiovascular disease. The Sundquist and Johansson (2004) paper is therefore useful to other researchers, as other researchers can see the exact methods used in this study, and can therefore build upon the results of this study, to contribute more to the scientific literature, which will, it is hoped, in turn then contribute to the development of medical strategies to overcome the development of cardiovascular disease. This is in contrast to the paper of Haffner and Cassells (2003), which, as we have seen, is of no real use to researchers in this field. In addition to not presenting any original research, and in contrast to the paper of Sundquist and Johansson (2004), the Haffner and Cassells (2003) paper is written in a rather undecipherable manner, with much information repeated throughout the course of the paper, and with information that is important being ‘hidden’ through indecipherable language and grammar. The paper is not, unlike the paper of Sundquist and Johansson (2004), an easy read, as its style of writing is rather tiresome and cumbersome. As discussed previously, scientific literature, good scientific literature, should be presented in as clear and as concise a manner as possible, in order that the results presented are easy to pick up quickly and accurately. Through this review of these two papers, we have seen that scientific papers vary greatly in terms of their quality, that is, in terms of the quality of the results and research presented, and also in terms of the quality of the writing and presentation. The two papers discussed here are extremely different in these terms: the Sundquist and Johansson (2004) paper is presented well, in that it is easy to understand and presents important original results, whereas the Haffner and Cassells (2003) paper is difficult to understand and does not present any original research; in addition, the research summaries it does present are presented in a confusing manner, with unclear writing and much repetition of information. On this basis, it is argued that the paper of Sundquist and Johansson (2004) is far more successful, scientifically, than the paper of Haffner and Cassells (2003). References Haffner, S.J. and Cassells, H. (2003). Hyperglycaemia as a cardiovascular risk factor. The American Journal of Medicine 115: 6S-10S. Sunquist, K. and Johansson, A. (2004). The long-term effect of physical activity on incidence of coronary heart disease: a 12-year follow up study. Preventative Medicine 41: 219-225. Read More