BODE Index for Predicting COPD Survival

Senior woman out of breath
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The BODE index is a tool that is used by healthcare professionals to predict the mortality rate (death rate) from chronic obstructive pulmonary disease (COPD). Using points based on 4 different measures of lung function, the BODE score makes a prediction about how long someone will live after a diagnosis of COPD.

The 4 Factors in the BODE Index

Four different factors are evaluated as part of the BODE index. The reason for this index is that each of these factors can make some prediction about the prognosis of COPD, but added together the prediction is more accurate. The letters stand for:

  • B - BMI - BMI stands for body mass index, a calculation made by comparing height vs weight.
  • O - Airway obstruction - Airway obstruction is measured by evaluating FEV1 — the amount of air that can be forcefully exhaled in 1 second after a deep breath.
  • D - Dyspnea - Dyspnea refers to the degree of breathlessness someone experiences while living with COPD.
  • E - Exercise tolerance - Exercise testing refers to how well some does on a 6-minute walk test.

Let's look at each of these measures separately, and then put them together in measuring the BODE index.

B - Body Mass Index

BMI is a calculation that is made by comparing height in meters by weight in kilograms. There are calculators for determining BMI, as well as tables BMI is an estimate of how overweight or underweight a person is. With COPD, being underweight or malnourished is a poor sign when it comes to prognosis.

O - Airway Obstruction

FEV1 (forced expiratory volume at 1 second) is a measure of the amount of air which can be forcefully exhaled in 1 second. FVC stands for forced vital capacity, which is the amount of air that can be exhaled altogether after a deep breath. The ratio FEV1/FVC, therefore, represents what percent of the total air that can be exhaled in 1 second over all the air that can be exhaled. Normally this ratio is around 1, which means that we exhale the majority of air in the 1st second of exhalation. If there is an obstruction in the airways slowing or preventing this rapid exhalation of air, the ratio decreases.

D - Dyspnea

Dyspnea is the term that refers to the physical sensation of shortness of breath or breathlessness. Doctors may distinctions based on what someone may need to do — how active they are — before they become short of breath. At first, a person may only become breathless if they walk 5 miles. Later on, in COPD a person may note breathlessness with any movement at all. The symptom of dyspnea is objectified by a measurement called the modified MRC Dyspnea Index. In this measurement, breathlessness is measured on a scale of 0 to 4:

  • MMRC 0 - Breathless with only strenuous exercise
  • MMRC 1 - Short of breath when hurrying on the level or walking up a slight hill
  • MMRC 2 - Short of breath on level ground and needing to stop intermittently to rest due to breathlessness (and walks slower than other people of own age)
  • MMRC 3 - Short of breath and having to stop after walking about 100 meters or after a few minutes (even though walking at own pace)
  • MMRC 4 - Too breathless to leave house or breathless when dressing

E - Exercise Tolerance

Exercise tolerance refers to how active someone is able to be with the restrictions put forth by their lung disease. A test called a 6-minute walk test is used to obtain the value for the BODE index.

Values and Ranges

The following values are those that can be assigned to determine the BODE index. Note that a score can range from 0 to 10 total depending on how these add up.

B - Body Mass Index Values

  • 0 points for a BMI greater than 21
  • 1 point for a BMI less than 21

O - Airway Obstruction Values

  • 0 points for an FEV1 greater than 64%
  • 1 point for an FEV1 of 50-64%
  • 2 points for an FEV1 of 36-49%
  • 3 points for an FEV1 of less than 36%

D - Dyspnea Values

  • 0 points for a dyspnea index of 0-1
  • 1 point for a dyspnea index of 2
  • 2 points for a dyspnea index of 3
  • 3 points for a dyspnea index of 4-5

E - Exercise Tolerance Values

  • 0 point if able to walk over 349 meters
  • 1 point if able to walk 250-249 meters
  • 2 points if able to walk 150-249 meters
  • 3 points if able to walk 150 meters or less
Variable Points on BODE Index Points on BODE Index Points on BODE Index Points on BODE Index
0 1 2 3
FEV1 (% predicted) ≥65 50-64 36-49 ≤35
6-Minute Walk Test (meters) ≥350 250-349 150-249 ≤149
MMRC Dyspnea Scale 0-1 2 3 4
Body Mass Index >21 ≤21 ≤21 ≤21

Predicting Mortality

After obtaining a BODE index, mortality can be predicted. Please note that there are many other factors which can affect mortality in people with COPD, and this test is not perfect. Someone with a very high score could end up living for decades and someone with a low score could pass tomorrow. Tests like this are good for making general predictions and evaluating statistics, but they do not necessarily give predictive information for individual people.

Survival Rates

Approximate 4-year survival rates are then calculated as:

  • 0-2 points - 80%
  • 3-4 points - 67%
  • 5-6 points - 57%
  • 7-10 points - 18%

Life Expectancy

The BODE index is one generalized measurement but survival varies tremendously when talking about individual people. Learn about some of the factors which influence COPD expectancy along with what you can do to improve your personal survival chance. If your disease is worsening, you may wish to learn as well about what you can expect with end-stage COPD.

NOTE: The BODE Index is meant to be used as a tool, for informational purposes only. It should not replace the advice of a healthcare professional.

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