New York: Nearly one in every nine men and about one in 30 women are at risk of experiencing sudden cardiac death, most before the age 70, finds a study. Sudden cardiac death claims thousands of lives each year. It mostly occurs in people with no prior symptoms of cardiovascular disease. "Sudden cardiac death has been very hard to study because most patients had no history of heart problems and were not being monitored at the time of their death," said Donald Lloyd-Jones from Northwestern University in the US. The findings showed that sudden cardiac death risk was greater for men than women -- with an overall 10.9 per cent lifetime risk among all men at age 45 (roughly one in nine men) and a 2.8 per cent lifetime risk of among all women at age 45 (or about one in 30 women). Men with two or more major risk factors at all ages had even higher lifetime risks for of at least 12 per cent (or more than one in eight men). High blood pressure levels helped identify lifetime risk more accurately in both men and women than any other single risk factor. "Our paper sets the stage for thinking about how we can screen the population effectively to find out who's at risk," Lloyd-Jones said. For the study, published in the Journal of the American Heart Association, the team examined long-term data on more than 5,200 men and women aged 28-62. Focusing on four major risk factors -- blood pressure, total cholesterol, smoking, and diabetes - the researchers calculated overall cumulative lifetime risk estimates for sudden cardiac death, and estimates according to risk factor burden. During follow up, 375 people died of sudden cardiac arrest.