Working long hours? Watch out for your heart‎ problems

When a patient comes into the office, it is important to do a risk assessment for cardiovascular disease. Many doctors use a tool called the Framingham risk score.

We take data on a lot of risk factors that are routinely measured. These include your age, gender, lipid levels, blood pressure and history of smoking. We then get a score that can stratify you to low moderate or high risk. Additional history such as if you are diabetic or have a first-degree family member with early heart disease acts as a multiplier. The tool helps us to decide whether or not we address your cholesterol level with lifestyle changes alone or whether or not medication must be added. This week, a study in the Annals of Internal Medicine looked at the impact of long working hours and whether or not that would modify the assessed risk. The typical risk assessment tool we use does not take into account psychosocial factors. 

In this study, the researchers looked at more than 7,000 civil service workers who were between 39 and 62 years old. None of the people had any signs of heart disease at the beginning of the study. They were followed for an average of 12 years. The patients were screened for heart disease every five years until 2004. About half of the participants worked 7 to 8 hours a day (54%). About 10.4% worked 11 hours or more a day. Those who worked 10 hours a day had a 45% increase risk for a coronary event compared to those who worked 7-8 hours a day. If you worked 11 hours a day then the risk jumped to 67% over the baseline.

By adding working hours as a separate but additional risk factor, it reclassified participants on occasion to a different risk category. In fact, the reclassification was a better fit when working hours were used as opposed to the model that used the Framingham risk score alone. This would be particularly important for those who jumped from moderate risk to high-risk assessments. The medical literature has studies that do speak to long working hours and heart disease. Six studies looking at different populations such as Sweden, Netherland, the UK and Japan have shown a statistically significant positive association, which simply means that the risk for heart diseases, such as heart attack and death from heart disease, is greater in those working overtime.

By considering working hours to assess heart disease, it is possible we have another risk factor that is easy to assess by simply asking detailed questions about work in a routine check-up. It is not possible to assess whether or not working hours are a cause of heart disease and therefore modifiable prevention.  It is important however to consider the potential role of our work on our health!

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