Long working hours linked to increased risk of coronary heart disease

According to a recent poll, 18% of adults employed full-time in the US work more than 60 hours a week. Although these long hours may benefit pay packets, the same may not be said for heart health; a new study suggests long working hours may increase the risk of coronary heart disease.

Heart disease is the leading cause of death in the US, killing around 600,000 people every year. Coronary heart disease (CHD) is the most common form of the condition, responsible for around 380,000 of these deaths.

CHD occurs when plaque accumulates inside the coronary arteries - the arteries that supply the heart muscle with oxygen-rich blood. The plaque can harden or rupture over time, restricting or blocking blood flow. The heart muscle can then become weakened, leading to arrhythmias - irregular heart beats - and heart failure.

According to the research team, including senior author Dr. Yun-Chul Hong of the Medical Research Center and College of Medicine at Seoul National University in South Korea, past studies have linked long working hours to adverse health outcomes, such as hypertension, diabetes, sleep problems and poor psychological health.

"Working hours not only affect physical health outcomes, but also lifestyle conditions, such as dietary patterns, exercise, smoking habits, and alcohol consumption," the researchers note. "It is highly probable that cardiovascular diseases are affected by overtime work, because the risk factors of cardiovascular diseases are influenced by working hours."
Working 61-70 hours a week linked to 42% increased risk of CHD

In this study, recently published in the American Journal of Industrial Medicine, Dr. Hong and colleagues wanted to see how working hours affected the risk of CHD.

Fast facts about CHD

The risk of CHD increases after the age of 45 for men and 55 for women
One of the most common symptoms of CHD is angina - chest pain or discomfort caused by lack of oxygen-rich blood reaching the heart muscle
Some people with CHD can treat the condition simply by making lifestyle changes, such as following a healthy diet and increasing exercise.

They assessed 8,350 participants aged 19 or over who were a part of the Korean National Health and Nutrition Examination Survey IV (2007-09).

The participants were asked about their working hours, general health and lifestyle factors, such as diet, exercise, smoking habits and alcohol consumption. They also underwent a physical examination, and their blood pressure, total cholesterol levels, fasting plasma glucose levels, triglyceride levels and high-density lipoprotein levels were measured.

The subjects' 10-year risk of CHD was assessed using the Framingham risk model - a scoring system that uses an array of information to calculate an individual's likelihood of developing cardiovascular diseases within a certain time period.