A large-scale study of nearly 80,000 patients suggests men develop atrial fibrillation (AFib) an average of 10 years earlier than women, according to researched from the American Heart Association.

In addition to sex differences, study author Christina Magnussen, MD, and colleagues found body mass index had a significant impact on likelihood of developing the condition, which is characterized by an irregular heartbeat and increased risks of stroke and death. According to an AHA report, untreated AFib leads to a five-times increased risk of stroke and a threefold increase in risk of mortality.

“It’s crucial to better understand modifiable risk factors of atrial fibrillation,” Magnussen said in the report. “If prevention strategies succeed in targeting these risk factors, we expect a noticeable decline in new-onset atrial fibrillation.”

The researchers, whose results will be published in the AHA journal Circulation Oct. 17, reviewed the records of 79,793 Europeans in four community-based studies across the continent. The patients, ranging between 24 and 97 years old at the baseline of the study, hadn’t been diagnosed with AFib prior to the trial.

Magnussen and her team followed the medical data of these individuals for between 12 and 28 years, eventually finding more men had been diagnosed with AFib—6.4 percent of the pool—by the study’s conclusion. Women had a lower rate of diagnosis at 4.4 percent.

By the time patients were 90 years old, around 24 percent had developed AFib.

The onset of AFib was linked to age in both sexes, higher blood levels of C-reactive protein in men and BMI in both men and women. Men see a sharp increase in AFib symptoms after they turn 50, the research stated, while women are more likely to develop the condition a decade later, after they reach 60. The association between weight and risk seemed to be much more significant in men than in women—men saw higher risks of AFib with a 31 percent increase in BMI, and women witnessed those same high risks with an 18 percent increase in BMI.

“We advise weight reduction for both men and women,” Magnussen said. “As elevated body mass index seems to be more detrimental for men, weight control seems to be essential, particularly in overweight and obese men.”

Magnussen and co-authors also found a link between total cholesterol and risk of developing AFib. The tie, which connected higher cholesterol levels in women with a decreased risk of AFib, “surprised” researchers, according to the AHA report.

The report stated Magnussen and colleagues haven’t been able to delineate the pathophysiological factors causing sex differences in AFib risk, but felt they could generalize their results to a larger population. The study focused on both northern and southern Europe, a mostly Caucasian region, Magnussen said, so her team’s findings could likely be applied to other Caucasian populations. The BMI connection could probably be applied to other, more diverse groups, she said, since it was such a strong risk factor.

The AHA estimates between 2.7 and 6 million Americans are currently living with AFib. According to research, more than 12 million Americans are expected to develop the condition by 2030.