Predictive properties of different multidimensional staging systems in patients with chronic obstructive pulmonary disease

Toru Oga¹, Mitsuhiro Tsukino², Takashi Hajiro³, Akihiko Ikeda⁴, Koichi Nishimura^5
1Department of Respiratory Care and Sleep Control Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan; ²Department of Respiratory Medicine, Hikone Municipal Hospital, Hikone, Japan; ³Department of Respiratory Medicine, Tenri Hospital, Tenri, Japan; ⁴Department of Respiratory Medicine, Nishi-Kobe Medical Center, Kobe, Japan; ⁵Department of Respiratory Medicine, Rakuwakai Otowa Hospital, Kyoto, Japan

Background: Chronic obstructive pulmonary disease (COPD) is considered to be a respiratory disease with systemic manifestations. Some multidimensional staging systems, not based solely on the level of airflow limitation, have been developed; however, these systems have rarely been compared.
Methods: We previously recruited 150 male outpatients with COPD for an analysis of factors related to mortality. For this report, we examined the discriminative and prognostic predictive properties of three COPD multidimensional measurements. These indices were the modified BODE (mBODE), which includes body mass index, airflow obstruction, dyspnea, and exercise capacity; the ADO, composed of age, dyspnea, and airflow obstruction; and the modified DOSE (mDOSE), comprising dyspnea, airflow obstruction, smoking status, and exacerbation frequency.
Results: Among these indices, the frequency distribution of the mBODE index was the most widely and normally distributed. Univariate Cox proportional hazards analyses revealed that the scores on three indices were significantly predictive of 5-year mortality of COPD (P < 0.001). The scores on the mBODE and ADO indices were more significantly predictive of mortality than forced expiratory volume in 1 second, the Medical Research Council dyspnea score, and the St. George's Respiratory Questionnaire total score. However, peak oxygen uptake on progressive cycle ergometry was more significantly related to mortality than the scores on the three indices (P < 0.0001).
Conclusion: The multidimensional staging systems using the mBODE, ADO, and mDOSE indices were significant predictors of mortality in COPD patients, although exercise capacity had a more significant relationship with mortality than those indices. The mBODE index was superior to the others for its discriminative property. Further discussion of the definition of disease severity is necessary to promote concrete multidimensional staging systems as a new disease severity index in guidelines for the management of COPD.

Keywords: COPD, multidimensional staging systems, BODE index, ADO index, DOSE index