The numbers game: Risk factors, lifestyle, and longevity

Content provided by the Faculty of the Harvard Medical School

How are you?

This simple question may soon give way to a growing array of more sophisticated queries: What's your cholesterol? Your blood pressure? Your weight? Your PSA? And with increasing health awareness, even these inquiries are beginning to sound quaint, as men ask about LDL and HDL cholesterol levels, systolic and diastolic blood pressures, BMIs and waist circumferences, free and total PSAs.

To men who grew up in a simpler era, it must seem like a tyranny of numbers. Knowing your numbers may stand you in good stead on the 19th hole, but do they really matter for your future health? Researchers have wondered, too — and their answers are good news for gents with good numbers, especially if they also have good health habits. And here's more good news: you don't need the latest sophisticated numbers to know where you stand. Instead, a few simple measurements and health habits will do — and good results in midlife predict successful aging and longevity.

Major studies, major impact

Back in 1999, an extraordinarily large study evaluated the impact of just three risk factors: total cholesterol below 200 mg/dL, a blood pressure of 120/80 mm Hg or lower, and no current cigarette smoking. The participants included 360,430 men between the age of 18 and 59. Men who had all three favorable risk factors enjoyed 50% to 58% lower mortality rates than their peers with less favorable profiles.

A smaller study of 6,342 people in the Chicago area shows the power of four simple cardiovascular risk factors. All the participants were healthy when the trial began. Researchers tracked the volunteers for an average of 26 years to see if risk factors in middle age predict quality of life in older age. The four risk factors in this study were high blood pressure, high total cholesterol, smoking, and the presence of minor EKG abnormalities. People who were free of risk factors in the late 1960s and early 1970s were consistently healthier when the results were tallied in 1996. The more risk factors that were present in middle-age, the greater the chance of illness during the next 26 years. And there's more: the low-risk people maintained better physical and mental function in their older years, and they reported a superior overall quality of life. A companion study of the same group of volunteers found that body mass index (BMI) had a similar predictive value: people who were lean in midlife were healthier and enjoyed a better quality of life in older age.

The Chicago studies included both men and women, but a newer study from Hawaii focused strictly on men. The 5,820 volunteers were between 45 and 68 when they enrolled. To establish a risk profile, each man underwent a detailed medical evaluation that included 29 individual factors. The scientists followed the men to learn if risk factors predicted healthy survival. The results were impressive: men who had no risk factors had a 55% chance of making it to age 85 without any major illness or disability, while men with six or more risk factors had just a 9% chance of exceptional survival. High blood sugar levels, high blood pressure, ever having smoked, and high alcohol consumption shared the dubious distinction of being the most dangerous risk factors; others included being overweight, having high triglyceride levels, being unmarried, having a low educational level, and having low grip strength.

Gripping results

Handgrip strength is not one of the numbers that middle-age men usually worry about, but it has real predictive value. A Japanese study evaluated grip strength in 4,912 people age 35 to 74 when they enrolled between 1970 and 1972. Researchers tracked the volunteers through 1999. The men with the strongest handgrips at the start of the study enjoyed a 48% lower death rate than the men with the weakest grips, even after cholesterol, blood pressure, BMI, smoking, and drinking were taken into account.

Another little-publicized number with predictive value is height. British scientists measured 4,213 men when they were between the ages of 40 and 59, and then repeated the measurements 20 years later. Men who lost more than 1.2 inches of height had a 64% higher 20-year mortality rate than men who lost less than 0.4 inches. Most of the excess deaths were related to cardiovascular disease; height loss remained a significant risk factor even after standard cardiovascular risk factors were taken into account.

Grip strength and preserved height represent surrogate markers for musculoskeletal fitness and physical activity. Indeed, many studies agree that regular exercise and physical fitness predict longevity and good health.

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