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A combined pulmonary function and emphysema score prognostic index for staging in Chronic Obstructive Pulmonary Disease.

Boutou AK, Nair A, Douraghi-Zadeh D, Sandhu R, Hansell DM, Wells AU, Polkey MI, Hopkinson NS - PLoS ONE (2014)

Bottom Line: Pulmonary artery dimensions were not associated with survival.An emphysema score of 55% was chosen as the optimal threshold and 30% and 65% as suboptimals.This approach was more discriminatory for survival (HR = 3.123; 95% CI = 1.094-10.412) than either individual component alone.

View Article: PubMed Central - PubMed

Affiliation: NIHR Respiratory Biomedical Research Unit at Royal Brompton and Harefield NHS Foundation Trust and Imperial College, London, United Kingdom.

ABSTRACT

Introduction: Chronic Obstructive Pulmonary Disease (COPD) is characterized by high morbidity and mortality. Lung computed tomography parameters, individually or as part of a composite index, may provide more prognostic information than pulmonary function tests alone.

Aim: To investigate the prognostic value of emphysema score and pulmonary artery measurements compared with lung function parameters in COPD and construct a prognostic index using a contingent staging approach.

Material-methods: Predictors of mortality were assessed in COPD outpatients whose lung computed tomography, spirometry, lung volumes and gas transfer data were collected prospectively in a clinical database. Univariate and multivariate Cox proportional hazard analysis models with bootstrap techniques were used.

Results: 169 patients were included (59.8% male, 61.1 years old; Forced Expiratory Volume in 1 second % predicted: 40.5±19.2). 20.1% died; mean survival was 115.4 months. Age (HR = 1.098, 95% Cl = 1.04-1.252) and emphysema score (HR = 1.034, 95% CI = 1.007-1.07) were the only independent predictors of mortality. Pulmonary artery dimensions were not associated with survival. An emphysema score of 55% was chosen as the optimal threshold and 30% and 65% as suboptimals. Where emphysema score was between 30% and 65% (intermediate risk) the optimal lung volume threshold, a functional residual capacity of 210% predicted, was applied. This contingent staging approach separated patients with an intermediate risk based on emphysema score alone into high risk (Functional Residual Capacity ≥210% predicted) or low risk (Functional Residual Capacity <210% predicted). This approach was more discriminatory for survival (HR = 3.123; 95% CI = 1.094-10.412) than either individual component alone.

Conclusion: Although to an extent limited by the small sample size, this preliminary study indicates that the composite Emphysema score-Functional Residual Capacity index might provide a better separation of high and low risk patients with COPD, than other individual predictors alone.

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Kaplan Meier curves for the COPD population, categorized according to A) ES optimal threshold of 55%, B) ES subthresholds of 30 and 65%, C) FRC % predicted optimal threshold of 210% and D) ES-FRC composite index.
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pone-0111109-g001: Kaplan Meier curves for the COPD population, categorized according to A) ES optimal threshold of 55%, B) ES subthresholds of 30 and 65%, C) FRC % predicted optimal threshold of 210% and D) ES-FRC composite index.

Mentions: In univariate survival analysis ES was a strong, independent predictor of mortality and its prognostic value was tested using several threshold values from 20 to 70 (Table 4). Although several cut-off values were significantly associated with mortality, the 55% was selected as optimal. The 55% cut-off separated the population in two subgroups: a smaller one with ES≥55% (N1 = 64; 37.9%) with a mean survival of 94.6 (71.8–117.4) months, and a larger one with ES<55% (N2 = 105; 62.1%) and a mean survival of 116 (103.9–128.1) months (p = 0.003) (Figure 1A). In patients with ES<55% mortality was not associated with ES (HR = 1.029; 95% CI = 0.992–1.097), while in patients with ES≥55% there was a definite association between ES and mortality (HR = 1.097; 95% CI = 1.003–1.228). Compared to the other three thresholds which separated the patient population in a similar manner (that is the 45%, the 50% and the 60% threshold) the 55% cut-off point also had the highest AUC when it was evaluated by the ROC curve method (Figure S1).


A combined pulmonary function and emphysema score prognostic index for staging in Chronic Obstructive Pulmonary Disease.

Boutou AK, Nair A, Douraghi-Zadeh D, Sandhu R, Hansell DM, Wells AU, Polkey MI, Hopkinson NS - PLoS ONE (2014)

Kaplan Meier curves for the COPD population, categorized according to A) ES optimal threshold of 55%, B) ES subthresholds of 30 and 65%, C) FRC % predicted optimal threshold of 210% and D) ES-FRC composite index.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4208797&req=5

pone-0111109-g001: Kaplan Meier curves for the COPD population, categorized according to A) ES optimal threshold of 55%, B) ES subthresholds of 30 and 65%, C) FRC % predicted optimal threshold of 210% and D) ES-FRC composite index.
Mentions: In univariate survival analysis ES was a strong, independent predictor of mortality and its prognostic value was tested using several threshold values from 20 to 70 (Table 4). Although several cut-off values were significantly associated with mortality, the 55% was selected as optimal. The 55% cut-off separated the population in two subgroups: a smaller one with ES≥55% (N1 = 64; 37.9%) with a mean survival of 94.6 (71.8–117.4) months, and a larger one with ES<55% (N2 = 105; 62.1%) and a mean survival of 116 (103.9–128.1) months (p = 0.003) (Figure 1A). In patients with ES<55% mortality was not associated with ES (HR = 1.029; 95% CI = 0.992–1.097), while in patients with ES≥55% there was a definite association between ES and mortality (HR = 1.097; 95% CI = 1.003–1.228). Compared to the other three thresholds which separated the patient population in a similar manner (that is the 45%, the 50% and the 60% threshold) the 55% cut-off point also had the highest AUC when it was evaluated by the ROC curve method (Figure S1).

Bottom Line: Pulmonary artery dimensions were not associated with survival.An emphysema score of 55% was chosen as the optimal threshold and 30% and 65% as suboptimals.This approach was more discriminatory for survival (HR = 3.123; 95% CI = 1.094-10.412) than either individual component alone.

View Article: PubMed Central - PubMed

Affiliation: NIHR Respiratory Biomedical Research Unit at Royal Brompton and Harefield NHS Foundation Trust and Imperial College, London, United Kingdom.

ABSTRACT

Introduction: Chronic Obstructive Pulmonary Disease (COPD) is characterized by high morbidity and mortality. Lung computed tomography parameters, individually or as part of a composite index, may provide more prognostic information than pulmonary function tests alone.

Aim: To investigate the prognostic value of emphysema score and pulmonary artery measurements compared with lung function parameters in COPD and construct a prognostic index using a contingent staging approach.

Material-methods: Predictors of mortality were assessed in COPD outpatients whose lung computed tomography, spirometry, lung volumes and gas transfer data were collected prospectively in a clinical database. Univariate and multivariate Cox proportional hazard analysis models with bootstrap techniques were used.

Results: 169 patients were included (59.8% male, 61.1 years old; Forced Expiratory Volume in 1 second % predicted: 40.5±19.2). 20.1% died; mean survival was 115.4 months. Age (HR = 1.098, 95% Cl = 1.04-1.252) and emphysema score (HR = 1.034, 95% CI = 1.007-1.07) were the only independent predictors of mortality. Pulmonary artery dimensions were not associated with survival. An emphysema score of 55% was chosen as the optimal threshold and 30% and 65% as suboptimals. Where emphysema score was between 30% and 65% (intermediate risk) the optimal lung volume threshold, a functional residual capacity of 210% predicted, was applied. This contingent staging approach separated patients with an intermediate risk based on emphysema score alone into high risk (Functional Residual Capacity ≥210% predicted) or low risk (Functional Residual Capacity <210% predicted). This approach was more discriminatory for survival (HR = 3.123; 95% CI = 1.094-10.412) than either individual component alone.

Conclusion: Although to an extent limited by the small sample size, this preliminary study indicates that the composite Emphysema score-Functional Residual Capacity index might provide a better separation of high and low risk patients with COPD, than other individual predictors alone.

Show MeSH
Related in: MedlinePlus