The newspaper reported that for the first time doctors have quantified the effects of smoking, high blood pressure, and high cholesterol, described as “the three major killers of middle-aged men”. Failing to give up smoking or to control blood pressure and cholesterol were reported to reduce life expectancy by 10 to 15 years.

The Whitehall study that provided the data set for this new publication is a large cohort study that started in 1967. It provides over 30 years of follow-up data for cause-specific mortality in a large population of civil servants.

This study found that there has been a clear improvement in rates of cardiovascular deaths across the decades, and also an improvement in the control of high blood pressure and high cholesterol, in addition to a reduction in smoking rates.

However, despite this, those with the combined risk factors of smoking, high cholesterol and high blood pressure when aged 50 were found live an average of 10 years less than those without.

The study has only been conducted in a specific population of men but the findings concur with the numerous other health studies demonstrating the impact of smoking, blood pressure and cholesterol upon health and mortality. The study did not specifically assess alcohol use.

Where did the story come from?

This research was conducted by Robert Clarke and colleagues of University of Oxford, University College London Medical School and the London School of Hygiene and Tropical Medicine.

What kind of scientific study was this?

The Whitehall study is a large cohort study collecting many types of data from workers in the civil service. It used data collected from 19,019 men aged between 40 and 69 years. Subjects were entered into the study from 1967 to 1970 and 99% of the subjects were followed up to 2005.

What were the results of the study?

The WHO data showed that between 1950 and 2005, standardised rates of UK mortality due to cardiovascular causes in middle-aged men were about twice of those for middle-aged women. However, for both men and women there has been an improvement in mortality rates over time, with a decline of about 2% a year from 1970 onwards.

At the start of the Whitehall study, 42% of the men currently smoked, 39% had high blood pressure, and 51% had high cholesterol. At a re-examination stage in 1997, 13% were current smokers and 58% were ex-smokers, with an average quitting age of 52 years). Only one-third of those smoking at study start were still smoking.

About a quarter of all deaths in the cohort occurred before the age of 70.

What interpretations did the researchers draw from these results?

The researchers conclude that, despite substantial changes in the risk factors of smoking, cholesterol and blood pressure over the 30 years, baseline differences in risk factors were associated with 10 to 15 year shorter life expectancy from age 50 onwards.

NHS findings

The findings concur with the numerous other health studies that demonstrate the impact that smoking, blood pressure and cholesterol can have upon health and mortality. While this will be unsurprising to most people, the study has strengths in providing an estimation of the size of this risk. As the authors conclude, continued public health strategies to lower these risk factors could result in further improvements in life expectancy.