BODE Index for Predicting COPD Survival

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 four different measures of lung function, the BODE score makes a prediction about how long someone will live after a diagnosis of COPD.

Senior woman out of breath — Science Photo Library / Getty Images

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:

Body Mass Index (BMI) is a calculation made by comparing height vs weight.
Airway Obstruction: Airway obstruction is measured by evaluating FEV1 — the amount of air that can be forcefully exhaled in one second after a deep breath.
Dyspnea refers to the degree of breathlessness someone experiences while living with COPD.
Exercise tolerance refers to how well someone 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.

BMI is a dated, flawed measure. It does not take into account factors such as body composition, ethnicity, sex, race, and age.
Even though it is a biased measure, BMI is still widely used in the medical community because it’s an inexpensive and quick way to analyze a person’s potential health status and outcomes.

O - Airway Obstruction

Forced expiratory volume in one second (FEV1) is a measure of the amount of air that can be forcefully exhaled in one second. The forced vital capacity (FVC) measurement shows the amount of air a person can forcefully and quickly exhale after taking a deep breath. The ratio FEV1/FVC, therefore, represents the total percentage of air that can be exhaled in one second. A normal FEV1/FVC ratio in adults is 0.70 or greater, while in children a normal ratio is 0.80 or greater. 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 modified Medical Research Council dyspnea scale (mMRC) is frequently used to evaluate dyspnea related to COPD. In this measurement, breathlessness is measured on a scale of 0 to 4:

mMRC Grade 0: Breathless with only strenuous exercise
mMRC Grade 1: Short of breath when hurrying or walking up a slight hill
mMRC Grade 2: Walks slower than peers on level ground because of breathlessness or has to stop for breath when walking at own pace
mMRC Grade 3: Stops for breath after walking 100 meters or after a few minutes
mMRC Grade 4: Too breathless to leave the house or breathless when dressing or undressing

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.

Variable	Points on BODE Index	Points on BODE Index	Points on BODE Index	Points on BODE Index
	0	1	2	3
FEV1 (% of predicted)	≥65	50-64	36-49	≤35
Distance walked in 6 minutes (meters)	≥350	250-349	150-249	≤149
mMRC dyspnea scale	0-1	2	3	4
BMI	>21	≤21

Predicting Mortality

After obtaining a BODE index, mortality can be predicted. Please note that there are many other factors that 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 based on the BODE index point system above is as follows:

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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