Christine F. McDonald, MBBS, PhD
In patients with chronic obstructive pulmonary disease (COPD), how do discrimination and calibration for prognosis compare for 3 clinical prediction guides?
Validation of the original BODE index, and derivation and validation of an updated BODE index and a simplified ADO index in 2 cohorts.
Switzerland and Spain.
The Swiss cohort consisted of 232 patients (mean age 72 y, 60% men) with long-standing and severe COPD. The Spanish cohort consisted of 342 patients (mean age 68 y, 93% men) who had recently been hospitalized for a first COPD exacerbation. Mean values of predictor variables in the Swiss and Spanish cohorts, respectively, were body mass index (BMI) 26 and 28 kg/m2; FEV1 45% and 52% of predicted; dyspnea score 2.2 and 2.1; and 6-minute walk distance 363 and 441 m.
Original BODE index (range 0 to 10, worst): BMI (B), 0 or 1 point; airway obstruction (FEV1) (O), 0 to 3 points; dyspnea (Medical Research Council dyspnea scale, range 0 to 4, worst) (D), 0 to 3 points; and exercise capacity (6-min walk test) (E), 0 to 3 points.* Updated BODE index (range 0 to 15, worst): same as the original BODE index except categories of FEV1 are compressed so that the maximum point score is 2, and more points are assigned for poor outcomes on the 6-minute walk test, up to 9. ADO index (range 0 to 10, worst): age (A), 0 to 5 points; dyspnea (D), 0 to 3 points; and FEV1 (O), 0 to 2 points. The 2 new indices were derived in the Swiss cohort and validated in the Spanish cohort.
All-cause mortality at 3 years.
The original BODE index had poor calibration (in the Swiss cohort, mortality was underpredicted by 36%, P = 0.013; in the Spanish cohort, mortality was overpredicted by 39%, P = 0.035) and discrimination (c statistic 0.67 and 0.62, respectively). In the validation (Spanish) cohort, the 2 new indices had excellent calibration (P = 0.99 for the updated BODE and 0.98 for the ADO) and similar discrimination to the original BODE index (c statistic 0.61 and 0.63, respectively) after adjustment for the difference in mortality between cohorts (Table).
In patients with chronic obstructive pulmonary disease, an updated BODE index and a simplified ADO index predicted 3-year mortality better than the original BODE index, with similar discrimination.
Mortality predicted by 2 indices in 2 cohorts with different severity of chronic obstructive pulmonary disease (COPD)
McDonald CF. An updated BODE index and a simplified ADO index predicted 3-year mortality in COPD better than the original BODE index. Ann Intern Med. 2010;152:JC1–12. doi: 10.7326/0003-4819-152-2-201001190-02012
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Published: Ann Intern Med. 2010;152(2):JC1-12.
Chronic Obstructive Airway Disease, Pulmonary/Critical Care.
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Print ISSN: 0003-4819 | Online ISSN: 1539-3704
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