Predicting Life Expectancy in People With COPD

Life expectancy for people with chronic obstructive pulmonary disease (COPD) can be predicted by assessing body mass index (BMI), airway obstruction, dyspnea, and exercise capacity, collectively called the BODE index.

While certainly a difficult topic to consider if you or a loved one have been diagnosed with the disease, learning the prognosis of COPD can be important. For some, it is what prompts them to make much-needed changes that may improve their quality of life and help them live longer.

In the end, the average life expectancy of persons with COPD is just that—an average. You can often exceed expectations by taking charge and addressing the factors that you can change. This article covers the factors affecting prognosis, the BODE index results, and the relationship between COPD and lung cancer.

Factors Affecting Prognosis

While there are no hard-and-fast rules that govern how long a person can live with COPD, a system called the BODE index has been developed to help with predictions.

The BODE index considers four different measures—body mass index (BMI), airway obstruction, dyspnea, and exercise tolerance—each of which is given a certain number of points. While individually informative, added together, these scores make a more accurate prediction about how long someone will live after a diagnosis of COPD.

Note, however, that the BODE index provides only a general prediction of mortality. There are many other factors that can affect mortality in people with COPD, and this test is not perfect.

B—Body Mass Index

Body Mass Index (BMI) is a calculation that is made by comparing height in meters by weight in kilograms. It is an estimate of how overweight or underweight a person is in relation to their body frame. With COPD, being underweight or malnourished is a poor sign for prognosis.

Keep in mind, however, that 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—Obstruction (of the Airway)

Measured by a simple test known as spirometry, airway obstruction typically looks at a marker called forced expiratory volume (FEV1), a measure of the percentage of air that can be forcefully exhaled in one second.

Normally, this percentage is greater than 65%, which means the majority of air is exhaled in the first second of breathing out. If there is an obstruction in the airways that slows or prevents this rapid exhalation of air, the percentage decreases.

FEV1 is a strong predictor of survival in people with COPD. Those with severe airway obstruction on long-term oxygen therapy have low survival rates (roughly 70% to year one, 50% to year two, and 43% to year three).

D—Dyspnea

Dyspnea is the physical sensation of shortness of breath or breathlessness. Healthcare providers make distinctions based on what someone may need to do—how active they are—before they become short of breath. Early on, a person with COPD may only become breathless if they walk 5 miles. Later on, that same person may note breathlessness with any movement at all.

The symptom of dyspnea is objectified by a measurement called the modified Medical Research Council (MMRC) 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 level ground or walking up a slight hill
• MMRC 2: Short of breath on level ground and needing to stop intermittently to rest due to breathlessness; walks slower than other people of identical 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 the house or breathless when dressing

Dyspnea evaluation rates a person's perception of their COPD symptoms and translates those perceptions into measurable value. While FEV1 has been regarded as the best way to predict COPD mortality, the dyspnea level may be more significant when predicting survival.

E—Exercise Tolerance

Exercise capacity—how active someone is able to be with the restrictions put forth by their lung disease—may be dramatically reduced by COPD.

A standard test called the six-minute walk test is used to obtain the exercise capacity value for the BODE index. It can provide both an estimate of hospitalizations and risk of death. Unintended stops during the test and other measured variables appear to be good prognostic factors in COPD.

BODE Index Results

After the appropriate points for the factors above have been determined, they are added together. The BODE index is graded on a scale of 0 to 10, with lower grades (final scores) corresponding to longer survival times and higher grades corresponding to shorter survival times:

In considering each of the individual values that go into the total BODE index score, your healthcare provider can offer ways to improve upon your grading.

Considerations

Tests like this are good for making general predictions and evaluating statistics, but they do not necessarily give predictive information for individual people. Someone with a very high score could end up living for decades, and the opposite could be true for someone with a low score.

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.

COPD and Lung Cancer Risk

Another major factor contributing to the life expectancy of someone with COPD is lung cancer risk. COPD is considered an independent risk factor for lung cancer, meaning that just having COPD greatly increases your chances of contracting cancer, regardless of whether you ever smoked cigarettes.

Nonsmokers with COPD are more likely to develop lung cancer than nonsmokers without COPD, and smokers with COPD are more likely to develop lung cancer than those who smoke and don't have COPD.

If you have COPD, talk to a healthcare provider about a lung cancer screening, and familiarize yourself with the symptoms of the condition.

Summary

Predicting life expectancy with COPD is not an exact science. The BODE index uses four measures to give a fairly accurate prognosis for someone with COPD, but it's not always right.

Talk to a healthcare provider about lung cancer screening, and remember that the BODE index doesn't dictate how long you have to live. Rather, it informs you in order to determine the steps you can take to improve your condition. Chief among these is smoking. No other changeable factor has a greater impact on your survival time than the habit of lighting up.