News
High Serum Uric Acid Linked to Increased Mortality Due to CHF and Stroke
Traditionally, elevated serum uric acid (SUA) is linked to gout. Recent investigations have shown that there may be a relationship between hyperuricemia and ischemic heart disease and metabolic syndrome, which is characterized by obesity, dyslipidemia, diabetes and hypertension. Although a direct relationship between SUA and cardiovascular disease is difficult to prove due to confounding factors like hypertension and diabetes, Strasak et al have recently demonstrated that SUA is an independent predictor of mortality due to congestive heart failure and stroke (Clinical Chemistry, 2007).
This was a prospective study that analyzed a cohort of 83,683 Austrian men (mean age, 41.6 years) who were followed up for a median of 13.6 years. Established risk factors, such as hypertension and diabetes, and SUA were studied, and the Cox proportional hazards model was used to adjust for these factors and for analyzing SUA as an independent risk factor for cardiovascular disease related mortality.
The team noted that the highest SUA levels were significantly associated with an increased mortality rate due to congestive heart failure (CHF, P = 0.03) and stroke (P < 0.0001). A stronger association was observed between SUA and fatal CHF in younger subjects. However, SUA did not correlate with the mortality due to coronary artery disease (acute, subacute or chronic) after adjusting for confounding factors.
Previously, Gerber et al (European Journal of Cardiovascular Prevention and Rehabilitation, 2006) had also documented an increased incidence of cardiovascular mortality among hyperuricemic subjects. But interestingly, they also found an association between low SUA levels and fatal stroke. In the Losartan Intervention For Endpoint reduction (LIFE) in hypertension study (Kidney International, 2004), the researchers observed that up to 29% of the reduction in the composite end point of death, myocardial infarction and stroke, is seen with the use of losartan, and this was attributable to a decrease in the SUA, implying a link between SUA and both stroke and coronary heart disease.
Madsen et al (American Journal of Nephrology, 2005) had also concluded that in patients not using diuretics, with significant, angiographically defined CAD, the SUA predicted mortality, independent of traditional risk factors. Although the findings of Strasak et al are contradictory in this regard, whether they held true regardless of diuretic use is not known.
Follow up studies and further research examining the association between uric acid and cardiovascular diseases and stroke will be helpful in understanding any direct causal risk in the etiopathogenesis.