This I Believe

Michael - Beachwood, Ohio
Entered on January 2, 2007
Age Group: 30 - 50
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The Power of Data

Submitted by Michael S Lauer, MD, FACC, FAHA

Professor of Medicine, Epidemiology, and Biostatistics

Cleveland Clinic Lerner College of Medicine of Case Western Reserve University

Desk JJ40, 9500 Euclid Avenue

Cleveland, OH 44195

Phone: 216 444 6798

Fax: 216 636 2574


Word count: 481

I believe in the power of data.

Seven years ago my research group published a paper about heart rates.1 My colleagues collected data on heart rates during and immediately after exercise in 2500 patients. I looked at something called “heart rate recovery,” simply the difference in heart rate at right at the end of exercise and the heart rate one minute later. I analyzed the data and discovered that if the heart rate did not go down by much during that first minute, death rates doubled over the next 5 years.

When the paper was published, the media pounced. I was inundated by calls from print, radio, and television journalists. “How could it be,” they asked, “that a simple measurement like heart rate recovery could predict death?” One reporter, though, asked something else: “Isn’t this obvious? Haven’t we known that if the pulse rate is high after exercise, one is bad shape? We learned that in high school gym!”

Thinking about that question made me realize that while the concept perhaps was obvious, the process of knowing about was hardly so. Yes, it’s true that having a high pulse rate after exercise implies being in poor physical shape. Alert gym teachers and coaches figured that out. But knowing that this measure predicts long-term death rates—for that, one needs to harness the power of data.

Perhaps the first modern example of the power of data in health was the 1854 London cholera epidemic. I recently read Steven Johnson’s fascinating book “The Ghost Map,” which describes how Dr. Snow and Rev. Whitehead systematically recorded lots of data during the days immediately after the outbreak. While the establishment’s belief was that bad odors caused the disease, analyses of the data suggested otherwise. The disease spread by contaminated water from the Broad Street pump. Fortunately, the city authorities, skeptical as they were, agreed to close the pump, and the epidemic abated.

Since then, there have been many instances in which the power of data has yielded life-saving insights. Because of data, we know about the dangers of smoking, environmental toxins, post-menopausal hormones, and fatty and sugary foods. Because of data, we know about the benefits of physical activity, cholesterol-lowering drugs, defibrillators, and diets rich in green leafy vegetables and fish.

Like parenting (and many other things in life), data need quality and quantity to have power and value. Quality means standard and objective definitions, uniform and unbiased methods of collection and measurement, and easy ability to query. Quantity means collecting many measurements on many people.

Like other powerful tools, data can be used and abused. When, as Sherlock Holmes once quipped, theories take priority over data, we are misled. But it’s the theories and people behind them doing the misleading, not the data. When analyzed properly, unencumbered by biases, data makes it possible to understand and improve ourselves, our world and our shared destiny.

1. Cole CR, Blackstone EH, Pashkow FJ, Snader CE, Lauer MS. Heart-rate recovery immediately after exercise as a predictor of mortality. N Engl J Med. 1999;341:1351-7.