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Category Medicine & Tests

FEV₁ (% predicted) Post-bronchodilator value

— pts

6-Minute Walk Distance Best of two attempts

meters

— pts

mMRC Dyspnea Scale Select grade 0–4

— pts

Body Mass Index Weight (kg) / Height² (m²)

kg/m²

— pts

Clinical Presets:

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About

The BODE Index quantifies 4-year survival probability in patients with chronic obstructive pulmonary disease (COPD). Developed by Celli et al. and published in the New England Journal of Medicine (2004), it integrates four independent predictors: B (Body mass index), O (airflow Obstruction via FEV₁%), D (Dyspnea via mMRC scale), and E (Exercise capacity via 6-minute walk distance). Unlike FEV₁ alone, which captures only pulmonary mechanics, BODE incorporates systemic manifestations - cachexia, functional limitation, and perceived breathlessness - that independently predict mortality. Miscalculating this index leads to inappropriate palliative care timing, incorrect transplant referral urgency, or inadequate rehabilitation intensity. The composite score ranges from 0 to 10, where higher values indicate greater mortality risk: quartile 1 (score 0 - 2) carries approximately 20% 4-year mortality versus 80% in quartile 4 (score 7 - 10).

Formulas

The BODE Index is a simple additive model summing categorical scores from four domains:

BODE = B_score + O_score + D_score + E_score

where each component is scored as follows:

B_score =

{

0 if BMI > 211 if BMI ≤ 21

O_score =

{

0 if FEV₁% ≥ 651 if 50 ≤ FEV₁% ≤ 642 if 36 ≤ FEV₁% ≤ 493 if FEV₁% ≤ 35

D_score =

{

0 if mMRC ∈ {0, 1}1 if mMRC = 22 if mMRC = 33 if mMRC = 4

E_score =

{

0 if 6MWD ≥ 350m1 if 250 ≤ 6MWD ≤ 349m2 if 150 ≤ 6MWD ≤ 249m3 if 6MWD ≤ 149m

Variable definitions: BMI = body mass index in kg/m²; FEV₁% = forced expiratory volume in 1 second as percentage of predicted; mMRC = modified Medical Research Council dyspnea scale (0 - 4); 6MWD = 6-minute walk distance in meters.

Reference Data

Parameter	Points = 0	Points = 1	Points = 2	Points = 3
FEV₁ (% predicted)	≥ 65	50 - 64	36 - 49	≤ 35
6MWD (meters)	≥ 350	250 - 349	150 - 249	≤ 149
mMRC Dyspnea Scale	0 - 1	2	3	4
BMI (kg/m²)	> 21	≤ 21	-	-

BODE Quartile	Score Range	4-Year Mortality (%)	Median Survival	Clinical Action
Quartile 1	0 - 2	20%	> 80 months	Standard care, smoking cessation
Quartile 2	3 - 4	30%	60 - 80 months	Pulmonary rehabilitation
Quartile 3	5 - 6	40%	40 - 60 months	Transplant evaluation, LVRS consideration
Quartile 4	7 - 10	80%	< 36 months	Palliative care integration, transplant listing

mMRC Grade	Description
0	Dyspnea only with strenuous exercise
1	Short of breath when hurrying on level ground or walking up a slight hill
2	Walks slower than people of the same age on level ground due to breathlessness, or has to stop for breath when walking at own pace
3	Stops for breath after walking about 100 meters or after a few minutes on level ground
4	Too breathless to leave the house or breathless when dressing/undressing

Reference Study	n	Follow-up	Key Finding
Celli et al. (2004) NEJM	625	52 months	BODE better predicts mortality than FEV₁ alone (C-statistic 0.74)
Ong et al. (2005)	127	24 months	Each 1-point increase: HR 1.34 for mortality
Cote et al. (2008)	205	24 months	BODE change of ≥1 point predicts hospitalization
Martinez et al. (2008)	609	29 months	BODE predicts response to LVRS

Frequently Asked Questions

FEV1 captures only airflow limitation, a single physiological dimension. BODE integrates four domains: nutritional status (BMI), pulmonary mechanics (FEV1%), symptom burden (dyspnea), and functional capacity (6MWD). In the original Celli et al. validation, BODE achieved a C-statistic of 0.74 for mortality prediction versus 0.65 for FEV1 alone. Patients with identical FEV1 values can have dramatically different BODE scores based on exercise tolerance and cachexia, leading to different survival trajectories.

The BMI threshold of 21 kg/m² reflects the J-shaped mortality curve in COPD. Below this value, respiratory cachexia - driven by systemic inflammation and increased work of breathing - becomes a significant independent predictor of death. The binary scoring simplifies clinical application while capturing the critical inflection point. Obesity (BMI > 30) does not worsen prognosis in COPD and may even be protective (the 'obesity paradox'), hence no upper-range points.

Yes. BODE score ≥7 (Quartile 4) indicates median survival under 36 months, which aligns with transplant listing criteria requiring estimated 2-year mortality exceeding 50%. International guidelines recommend transplant evaluation when BODE reaches 5-6 (Quartile 3) to allow adequate time for workup. Serial BODE measurements showing progression of ≥1 point per year also trigger earlier referral regardless of absolute score.

The 6MWT must follow ATS/ERS guidelines: 30-meter flat corridor, standardized encouragement phrases at fixed intervals, oxygen supplementation only if prescribed for daily use (record flow rate). Patients should rest 10 minutes before testing and perform two walks separated by 30 minutes - use the higher distance. Testing within 4 weeks of exacerbation invalidates results. Walking aids are permitted but must be documented for longitudinal comparisons.

The original BODE validation excluded patients with asthma. In ACO, FEV1 variability after bronchodilation may artificially lower the O-score. Use post-bronchodilator FEV1% for BODE in ACO. Some studies suggest BODE remains predictive in ACO but with attenuated hazard ratios. For pure asthma without fixed obstruction, BODE is not validated and should not be applied.

Pulmonary rehabilitation primarily improves the E-component (6MWD) and D-component (dyspnea). A comprehensive 8-12 week program typically increases 6MWD by 25-50 meters and reduces mMRC by 0.5-1 grade. This can reduce BODE by 1-2 points. The Cote et al. study showed that improvement of ≥1 BODE point correlates with reduced hospitalization risk. Sustained benefit requires maintenance exercise programs.

BODE requires a 6-minute walk test, which demands corridor space, staff time, and patient ability to walk. It does not incorporate exacerbation frequency - a key prognostic factor addressed by the modified BODE-x and ADO indices. BODE was validated primarily in stable COPD; accuracy during acute exacerbations is uncertain. Additionally, FEV1% predicted requires appropriate reference equations matched to patient ethnicity and age.