Gout and the Impact on Cardiovascular Disease: Is There a Correlation?
Correlation is a statistical method of measuring associations or relationships between two variables. The purpose of researching correlations is to make predictions regarding one of the variables based on what we know about the other variable. Take for example the hypothesis of a correlation between Gout (X) and mortality from Cardiovascular Disease (Y1) (CVD), Coronary Heart Disease (Y2) (CHD), and/or fatal myocardial infarctions (Y3) (MI). If the results of the study show that people suffering from gout have higher rates of mortality from CVD, a positive correlation is demonstrated. The X & Y variables are interchangeable and the hypothesis could also be stated as (Y1, Y2, and Y3) increased incidence of mortality from CVD, CHD, and/or MI correlates to increased incidence of (X) Gout. When the results prove a correlation between the two variables, predictions can be made. If the sample population’s incidences of gout are known, we can predict outcomes related to mortality and CVD, CHD, and/or MI. The key concept to identifying these, or any, correlations is direction. There can be either positive correlation or negative correlation. These terms are a bit of a misnomer and students must understand that decreases that follow each other, such as mobility of joints (X) decreasing when kidney uric acid excretion decreases (Y); are still considered positive correlations. A negative correlation exists when the data show that increases in (X) lead to decreases in (Y) or decreases in (X) lead to increases in (Y). For example, as a patient’s age uric acid levels increase, vascular health decreases. This paper looks at a 2007 study, published in the journal Circulation, which attempts to link gout and hyperuricemia with increased mortality from CVD, CHD, and/or MI.
Gout is the most prevalent inflammatory disorder in males over 18 years of age it occurs in women but not until after menopause. It typically evidences itself as buildup of uric acid leads to painful crystal formations in the joints particularly the great toe. Other joints can also be affected. Along with the inflammation and pain there is a high degree of insult to the kidneys with can lead to stone formation and nephropathies. It is unknown whether or not gout shortens life expectancy directly but conditions associated with gout are known contributors to MI. Hyperuricemia can cause insulin resistance, obesity, and hypertension; all of which are associated with higher rates of mortality. During a 12-year the study, Choi and Curhan examined the possible relationship between a history of gout and the risk of fatal MI in 51,297 male participants of the Health Professionals Follow-Up Study. During the study, there were 5,825 deaths from all causes, including 2,132 deaths from CVD and 1576 deaths from CHD (2007).
According to Drs. Choi and Curhan, “the present study found that men with gout have a 28% higher risk of death from all causes, a 38% higher risk of cardiovascular disease death, and a 55% higher risk of death from coronary heart disease than men without gout (2007).” Choi and Curhan reported that gout was associated with a 26% increased risk of acute MI [multivariate odds ratio, 1.26; 95% confidence interval [CI], 1.14 to 1.40; P< 0.001](2007). Explicitly, the odds ratio is described as “multivariate” because it includes more than one outcome variable. Risk of mortality data includes CVD as well as both fatal and nonfatal MI. The P value, representing the significance of the findings, is less than 1/1000th which would be considered 99.9% confidence in the results. In statistics, the the results would be considered very highly significant.
I found the results compelling and…