Middle aged men who smoke, have high blood pressure and raised cholesterol levels can expect a 10-15 year shorter life expectancy from age 50 compared with men without these risk factors, concludes research published on bmj today.

Death rates from heart disease in the United Kingdom have declined steadily since the early 1970s, resulting in substantial improvements in life expectancy.

These improvements are believed to result from stopping smoking, changes in diet and lifestyle, and better treatment for people with vascular disease. Previous studies have not investigated the extent to which differences in life expectancy can be explained by differences in cardiovascular risk factors.

So researchers led by Dr Robert Clarke from the University of Oxford assessed life expectancy in relation to cardiovascular risk factors recorded in middle age.

Their findings are based on over 19,000 men aged 40-69 years and employed in the civil service in London when they were first examined in 1967-1970 as part of the Whitehall Study.

Participants completed a questionnaire at entry about previous medical history, smoking habits, employment grade and marital status. The initial examination recorded height, weight, blood pressure, lung function, cholesterol, and blood glucose levels.

The records of 18,863 men were traced and 7,044 surviving participants were re-examined in 1997 (around 28 years after their initial examination).

At entry into the study, 42% of the men were current smokers, 39% had high blood pressure and 51% had high cholesterol. At the re-examination, about two thirds had quit smoking and the mean differences in levels of blood pressure and cholesterol had also declined by two thirds over this period.

Despite changes in heart disease risk factors, the presence of three heart disease risk factors recorded on a single occasion in middle aged men compared to men with no risk factors predicted a three times higher risk of vascular mortality and a two times increased risk of non-vascular mortality.

Compared with men without any risk factors, the presence of all three risk factors at entry was associated with a 10 year shorter life expectancy from age 50 (23.7 versus 33.3 years).

The researchers then classified men according to a risk score based on all available risk factors (smoking, diabetes, employment grade, and continuous levels of blood pressure, cholesterol concentration, and body mass index). Compared with men in the lowest 5% of this risk score, men in the highest 5% had a 15 year shorter life expectancy from age 50 (20.2 versus 35.4 years).

Continued public health strategies to lower heart disease risk factors should result in further improvements in life expectancy, conclude the authors.

Link to paper

Source
British Medical Journal