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Original Articles

External Validation and Recalculation of the CODEX Index in COPD Patients. A 3CIAplus Cohort Study

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Pages 8-17 | Received 19 Jan 2018, Accepted 31 May 2018, Published online: 14 Mar 2019
 

Abstract

The CODEX index was developed and validated in patients hospitalized for COPD exacerbation to predict the risk of death and readmission within one year after discharge. Our study aimed to validate the CODEX index in a large external population of COPD patients with variable durations of follow-up. Additionally, we aimed to recalculate the thresholds of the CODEX index using the cutoffs of variables previously suggested in the 3CIA study (mCODEX).

Individual data on 2,755 patients included in the COPD Cohorts Collaborative International Assessment Plus (3CIA+) were explored. A further two cohorts (ESMI AND EGARPOC-2) were added. To validate the CODEX index, the relationship between mortality and the CODEX index was assessed using cumulative/dynamic ROC curves at different follow-up periods, ranging from 3 months up to 10 years. Calibration was performed using univariate and multivariate Cox proportional hazard models and Hosmer-Lemeshow test.

A total of 3,321 (87.8% males) patients were included with a mean ± SD age of 66.9 ± 10.5 years, and a median follow-up of 1,064 days (IQR 25–75% 426–1643), totaling 11,190 person-years. The CODEX index was statistically associated with mortality in the short- (≤3 months), medium- (≤1 year) and long-term (10 years), with an area under the curve of 0.72, 0.70 and 0.76, respectively. The mCODEX index performed better in the medium-term (<1 year) than the original CODEX, and similarly in the long-term.

In conclusion, CODEX and mCODEX index are good predictors of mortality in patients with COPD, regardless of disease severity or duration of follow-up.

Abbreviations
COPD=

Chronic Obstructive Pulmonary Disease

FEV1=

Forced Expiratory Volume in the first second

mMRC=

modified dyspnea scale of the Medical Research Council

3CIA=

COPD Cohorts Collaborative International Assessment

Post-BD=

post bronchodilator

STROBE=

STrengthening the Reporting of OBservational studies in Epidemiology

25–75% IQR=

25–75% interquartile range

ROC=

receiver operating characteristic curve

AUC=

area under the curve

NNE=

nearest-neighbor estimator

ESMI=

COPD in internal medical services

HR=

Hazard Ratio

95% C.I.=

95% Confidence Interval

CODEX index=

Comorbidity, Obstruction, Dyspnea, Exacerbations

mCODEX index=

modified CODEX index

BODE=

Body mass index, Obstruction, Dyspnea, Exercise

BODEX=

Body mass index, Obstruction, Dyspnea, Exacerbations

ADO=

Age, Dyspnea, Obstruction

HADO=

Health, Activity, Dyspnea, Obstruction

DOSE=

Dyspnea, Obstruction, Smoking, Obstruction

PEARL=

Previous admissions, eMRCD score, Age, Right-sided heart failure, Left-sided heart failure

Abbreviations
COPD=

Chronic Obstructive Pulmonary Disease

FEV1=

Forced Expiratory Volume in the first second

mMRC=

modified dyspnea scale of the Medical Research Council

3CIA=

COPD Cohorts Collaborative International Assessment

Post-BD=

post bronchodilator

STROBE=

STrengthening the Reporting of OBservational studies in Epidemiology

25–75% IQR=

25–75% interquartile range

ROC=

receiver operating characteristic curve

AUC=

area under the curve

NNE=

nearest-neighbor estimator

ESMI=

COPD in internal medical services

HR=

Hazard Ratio

95% C.I.=

95% Confidence Interval

CODEX index=

Comorbidity, Obstruction, Dyspnea, Exacerbations

mCODEX index=

modified CODEX index

BODE=

Body mass index, Obstruction, Dyspnea, Exercise

BODEX=

Body mass index, Obstruction, Dyspnea, Exacerbations

ADO=

Age, Dyspnea, Obstruction

HADO=

Health, Activity, Dyspnea, Obstruction

DOSE=

Dyspnea, Obstruction, Smoking, Obstruction

PEARL=

Previous admissions, eMRCD score, Age, Right-sided heart failure, Left-sided heart failure

Acknowledgments

The COCOMICS study was funded in part by a grant from the Spanish Society of Pneumology and Thoracic surgery (SEPAR) coded with the number 057/12.SEPAR 2013. We thank Tom Yohannan (professional medical copy-editor) for his editorial assistance.

Declaration of interest

Marc Miravitlles has received speaker or consulting fees from AstraZeneca, Bial, Boehringer Ingelheim, Chiesi, Cipla, CSL Behring, Laboratorios Esteve, Gebro Pharma, GlaxoSmithKline, Grifols, Menarini, Mereo Biopharma, Novartis, pH Pharma, Rovi, TEVA, Verona Pharma and Zambon, and research grants from GlaxoSmithKline and Grifols unrelated to this manuscript Pere Almagro has received speaker or consulting fees from Chiesi, AstraZeneca, Boehringer-Ingelheim, GlaxoSmithKline, Laboratorios Esteve, Rovi, Menarini y Novartis unrelated to this manuscript.

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