Body mass index, airflow obstruction and dyspnea and body mass index, airflow obstruction, dyspnea scores, age and pack years-predictive properties of new multidimensional prognostic indices of chronic obstructive pulmonary disease in primary care

Abstract

Background: The assessment of the severity of chronic obstructive pulmonary disease (COPD) should involve a multidimensional approach that is now clearly shown to be better than using spirometric impairment alone. The aim of this study is to validate and compare novel tools without an exercise test and to extend prognostic value to patients with less severe impairment of Forced expiratory volume 1 s.

Methods: A prospective, observational, primary care cohort study identified 458 eligible patients recruited from the primary care clinics in the northeast of England in 1999-2002. A new prognostic indicator - body mass index, airflow obstruction and dyspnea (BOD) together with the conventional prognostic indices age, dyspnea and airflow obstruction (ADO), global initiative for chronic obstructive lung disease (GOLD) and new GOLD matrix were studied. We also sought to improve prognostication of BOD by adding age (A) and smoking history as pack years (S) to validate BODS (BOD with smoking history) and BODAS (BOD with smoking history and age) as prognostic tools and the predictive power of each was analyzed.

Results: The survival of the 458 patients was assessed after a median of 10 years when the mortality was found to be 33.6%. The novel indices BOD, BODS, and BODAS were significantly predictive for all-cause mortality in our cohort. Furthermore with ROC analysis the C statistics for BOD, BODS, and BODAS were 0.62, 0.66, and 0.72, respectively (P < 0.001 for each), whereas ADO and GOLD stages had a C statistic of 0.70 (P < 0.001) and 0.56 (P < 0.02), respectively. GOLD Matrix was not significant in this cohort.

Conclusion: BOD, BODS, and BODAS scores are validated predictors of all-cause mortality in a primary care cohort with COPD.

Keywords: Age; airflow obstruction; body mass index; chronic obstructive pulmonary disease; dyspnea; mortality; multidimensional prognostic index; smoking history.

Figure 1

Kaplan–Meier survival analysis curves using BOD scores. BOD=Body mass index, airflow obstruction and dyspnea

Figure 2

KMSA curves representing the time course of the probability of survival for BOD categories (long rank test; P< 0.001). BOD=Body mass index, airflow obstruction and dyspnea, KMSA=Kaplan–Meier survival analysis

Figure 3

KMSA curves representing the time course of the probability of survival for BODS categories (long rank test; P< 0.001). BODS=Body mass index, airflow obstruction, dyspnea scores and pack years, KMSA=Kaplan–Meier survival analysis

Figure 4

KMSA curves representing the time course of the probability of survival for BODAS categories (long rank test; P< 0.001). BODAS=Body mass index, airflow obstruction, dyspnea scores, age and pack years, KMSA=Kaplan–Meier survival analysis

Figure 5

KMSA curves representing the time course of the probability of survival for GOLD stages (long rank test; P< 0.001). KMSA=Kaplan–Meier survival analysis, Gold=Global initiative for chronic obstructive lung disease

Figure 6

KMSA curves representing the time course of the probability of survival for ADO categories (long rank test; P< 0.001). ADO=Age, dyspnea and airflow obstruction, KMSA=Kaplan–Meier survival analysis, Gold=Global initiative for chronic obstructive lung disease

Figure 7

ROC curves for the respective scores of BODAS (0.72), ADO (0.71), BODS (0.66), BOD (0.63) scores, GOLD (0.56), GOLD matrix A–D (0.51). BOD=Body mass index, airflow obstruction and dyspnea, BODS=Body mass index, airflow obstruction, dyspnea scores and pack years, BODAS=Body mass index, airflow obstruction, dyspnea scores, age and pack years, ADO=Age, dyspnea and airflow obstruction, Gold=Global initiative for chronic obstructive lung disease

Figure 8

ROC curves for the respective categories of BODAS (0.69), ADO (0.71), BODS (0.65), BOD (0.60) scores, GOLD (0.56), GOLD matrix A–D (0.52). BOD=Body mass index, airflow obstruction and dyspnea, BODS=Body mass index, airflow obstruction, dyspnea scores and pack years, BODAS=Body mass index, airflow obstruction, dyspnea scores, age and pack years, ADO=Age, dyspnea and airflow obstruction, Gold=Global initiative for chronic obstructive lung disease