This is the first study to show that among men with no previous history of coronary artery disease, gout is a significant independent risk factor of heart attack.
Gout is a metabolic disease marked by acute arthritis and inflammation of the joints, usually beginning in the knee or foot. It is caused by hyperuricemia, a build up of uric acid in blood. When chronic or severe hyperuricemia leads to urate crystals within joints, it results in an inflammatory response that manifests as gouty arthritis.
"Our study confirms that gouty arthritis is an independent risk factor for myocardial infarction (MI) or heart attack. Until now this relationship has not been explained by well-known links to renal function, metabolic syndrome, diuretic use and the traditional cardiovascular risk factors," said Eswar Krishnan, M.D., assistant professor of medicine at the University of Pittsburgh School of Medicine, division of rheumatology, and principal author of the study.
The prospective study examined data from 12,866 men who were enrolled for a mean of 6.5 years in the Multiple Risk Factor Intervention Trial (MRFIT), a randomized primary cardiovascular disease prevention trial conducted and supported by the National Heart, Lung and Blood Institute.
There were 5,337 men with hyperuricemia at the beginning of the study. Over the study period, 1,123 individuals developed gouty arthritis. There was no statistically significant difference between the groups with regard to cholesterol levels, aspirin use, family history of acute MI, or diabetes mellitus. However, the group with gout was significantly more likely to have used diuretics and alcohol. Modest yet statistically significant elevations of blood pressure, age, blood glucose and body mass index were observed in the gout group. Subjects in the group with gout were less likely to be current smokers than were those in the group without gout.
During the course of the study, 1,108 events of acute MI occurred in the group with gout (10.5 percent) and 990 events in the group without gout (8.43 percent). Of the 1,108 MIs, 246 were fatal.
The study also found a relationship between gout and the risk of acute MI to be present among nonusers of alcohol, diuretics or aspirin and among those who did not have metabolic syndrome, diabetes mellitus or obesity.
"The absolute magnitude of the relative risk for the presence of gout was not high. Yet, the odds ratio associated with gout was relatively high compared to other risk factors in this study," Dr. Krishnan said. "For acute MI to occur, an environment that promotes atherogenesis and thrombogenesis is needed. Hyperuricemia is well known to be an independent risk factor for atherosclerotic diseases in general and since chronic hyperuricemia is strongly associated with gout, it is not very surprising that an independent coronary risk for the presence of both hyperuricemia and gout was observed."