In an analysis of cohort studies, a history of kidney stones was associated with an increased risk for coronary heart disease (CHD) and stroke. The data suggest that the risk may be higher in women than men.
The studies included close to 50,000 patients with kidney stones and 3.56 million controls. Results found kidney stone history to be associated with a 19% greater risk for CHD and a 40% greater risk for stroke. Additionally, women showed a statistically significant increased risk for myocardial infarction, while men did not.
The researchers noted that a lack of studies separately evaluating for effect modification by sex, along with other limitations, could explain the risk difference among men and women. Though, they added that several recent studies have shown a gender difference in kidney stone-related CHD and stroke risk.
One was reported in JAMA in July 2013. 
The prospective study included 45,748 men and 196,357 women in the U.S. without a history of CHD at baseline, including 19,678 who reported a history of kidney stones. Two cohorts of women and one of men were followed for up to 24 years.
The study found that women with a history of kidney stones had about an 18% increased risk for CHD and a 48% increased risk compared with women who had never had a kidney stone.
An even larger study from Alberta, Canada, reported in March of this year, showed similar differences in risk by gender.
The study included close to 3.2 million people registered in Alberta’s universal healthcare system between 1997 and 2009 who were followed for a median of 11 years.
The study showed that people who had at least one kidney stone had a 40% higher risk for heart attack, a 63% higher risk for blockage of blood flow to the heart and other organs, and a 26% higher risk for stroke. The magnitude of increased risk appeared more pronounced for women than men.
Both studies were included in the newly-published meta-analysis.
Gary C. Curhan, MD, who was a co-author on both, said the new data make a strong case for a real gender difference in cardiovascular disease risk associated with kidney stone history.
Curhan is a professor of medicine at Harvard Medical School and a renal disease specialist at Brigham and Women’s Hospital, Boston.
“The risk certainly seems to be higher in women than men, but I would not say the risk is zero in men.” “These two studies give us more confidence that this association is real. The next step is to try and answer the question ‘Why is there a difference?'”
Source: medpage Today