Classification of Airflow Limitation Based on <i>z</i>-Score Underestimates Mortality in Patients with Chronic Obstructive Pulmonary Disease

Tejero, Elena; Prats, Eva; Casitas, Raquel; Galera, Raúl; Pardo, Paloma; Gavilán, Adelaida; Martínez‐Cerón, Elisabet; Cubillos‐Zapata, Carolina; Peso, Luis del; García‐Río, Francisco

doi:10.1164/rccm.201611-2265oc

Cited by 26 publications

(18 citation statements)

References 28 publications

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“…Similar to our study, other studies have found that decreased ppFEV 1 , FEV 1 z‐score or FEV 1 Q are associated with an increased risk of death . Furthermore, a study by Mannino et al .…”

Section: Discussionsupporting

confidence: 92%

“…Similar to our study, other studies have found that decreased ppFEV 1 , FEV 1 z-score or FEV 1 Q are associated with an increased risk of death. 6,14,30,31 Furthermore, a study by Mannino et al 32 found that the risk of death increased with worsening GOLD-defined airflow limitation, where participants with severe or very severe obstruction were associated with 4.5 times higher risk of dying compared to participants with normal lung function. HR were slightly higher than in our study, likely due to the exclusion of participants with respiratory symptoms from their reference population.…”

Section: Discussionmentioning

confidence: 99%

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Comparison of pre‐ and post‐bronchodilator lung function as predictors of mortality: The HUNT Study

et al. 2019

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Background and objective Post‐bronchodilator (BD) lung function is recommended for the diagnosis of chronic obstructive pulmonary disease (COPD). However, often only pre‐BD lung function is used in clinical practice or epidemiological studies. We aimed to compare the discrimination ability of pre‐BD and post‐BD lung function to predict all‐cause mortality. Methods Participants aged ≥40 years with airflow limitation (n = 2538) and COPD (n = 1262) in the second survey of the Nord‐Trøndelag Health Study (HUNT2, 1995–1997) were followed up until 31 December 2015. Survival analysis and time‐dependent area under the receiver operating characteristic curves (AUC) were used to compare the discrimination ability of pre‐BD and post‐BD lung function (percent‐predicted forced expiratory volume in the first second (FEV1) (ppFEV1), FEV1 z‐score, FEV1 quotient (FEV1Q), modified Global Initiative for Chronic Obstructive Lung Disease (GOLD) categories or GOLD grades). Results Among 2538 participants, 1387 died. The AUC for pre‐BD and post‐BD ppFEV1 to predict mortality were 60.8 and 61.8 (P = 0.005), respectively, at 20 years' follow‐up. The corresponding AUC for FEV1 z‐score were 58.5 and 60.4 (P < 0.001), for FEV1Q were 68.7 and 70.1 (P = 0.002) and for modified GOLD categories were 62.3 and 64.5 (P < 0.001). Among participants with COPD, the AUC for pre‐BD and post‐BD ppFEV1 were 57.0 and 58.8 (P < 0.001), respectively. The corresponding AUC for FEV1 z‐score were 53.1 and 55.8 (P < 0.001), for FEV1Q were 63.6 and 65.1 (P = 0.037) and for GOLD grades were 56.0 and 57.0 (P = 0.268). Conclusion Mortality was better predicted by post‐BD than by pre‐BD lung function; however, they differed only by a small margin. The discrimination ability using GOLD grades among COPD participants was similar.

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“…Similar to our study, other studies have found that decreased ppFEV 1 , FEV 1 z‐score or FEV 1 Q are associated with an increased risk of death . Furthermore, a study by Mannino et al .…”

Section: Discussionsupporting

confidence: 92%

Section: Discussionmentioning

confidence: 99%

Comparison of pre‐ and post‐bronchodilator lung function as predictors of mortality: The HUNT Study

et al. 2019

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“…To estimate the implied impact on LE, we used a parametric survival function which was estimated using the functional form (Weibull, Gompertz or exponential) that minimized the Akaike information criteria (AIC). 26,27 The remaining LE were extrapolated using the estimated model taking into account the already known diagnoses of COPD, asthma and CVD at baseline and presented graphically as the remaining LE compared to the LE of a never smoker with no respiratory symptoms. CI for LE and years of life lost (YLL) were derived by bootstrapping (sampling with replacement) and used the 2.5 and 97.5 centiles from 2000 LE estimate repetitions.…”

Section: Discussionmentioning

confidence: 99%

Predicting life expectancy of older people using respiratory symptoms and smoking status: Data from the Australian Longitudinal Study of Ageing

et al. 2019

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Background and objective Respiratory symptoms are recognizable to patients and may be markers of chronic disease and mortality risk. This risk may be easier to conceptualize if presented as remaining life expectancy (LE) rather than hazard ratios. We aimed to predict the remaining LE of older people with respiratory symptoms using data from the Australian Longitudinal Study of Ageing (ALSA). Methods The ALSA is a prospective longitudinal cohort of older Australians (n = 2087) with 22 years of follow‐up. The symptoms analysed were cough, shortness of breath (SOB) and wheeze. The implied impact on LE was estimated using a parametric survival function. Results SOB predicted shorter LE irrespective of smoking status. Cough predicted shorter LE in former smokers and wheeze predicted shorter LE in current smokers. The estimated remaining LE of a 70‐year‐old male never smoker with no symptoms was 16.6 (95% CI: 14.8–17.7) years. The years of life lost for a 70‐year‐old male current smoker with cough, SOB and wheeze compared to a never smoker with no symptoms was 4.93 (95% CI: 2.87–7.36) years with only 2.99 (95% CI: 1.35–4.97) years being attributed to their current smoking and the remainder to their respiratory symptoms. Conclusion Respiratory symptoms predict mortality in older people. Cough in former smokers, wheeze in current smokers and all those with SOB require further investigations and disease‐specific management.

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“…While the ATS/ERS classification is based on the FEV 1 expressed in percentage of the predicted value (%pred) [1], the GLI new classification is based on the FEV 1 Z -scores [3]. This could be a source of confusion [6,8]. …”

mentioning

confidence: 99%

“…This study finding do not support the above conclusions. In the cohort study of Tejero et al [8] ( n = 2614 patients with chronic obstructive pulmonary disease (COPD)), based on ATS/ERS [1] and GLI [11] classifications, 33.2% and 35.7% had mild, 39.9% and 36.2% had moderate, 18.5% and 20.9% had severe, and 8.3% and 7.3% had very severe OVD. Like in this study, in the aforementioned one [8], the classification based on Z -score [3] showed little concordance with the ATS/ERS classification [1]: according to the Z -score classification [3], 66.3% of COPD remained with the same severity, while 23.7% worsened and 10.0% improved.…”

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confidence: 99%

Defining and grading an obstructive ventilatory defect (OVD): ‘FEV₁/FVC lower limit of normal (LLN) vs. Z-score’ and ‘FEV₁ percentage predicted (%pred) vs. Z-score’

Kammoun

Ghannouchi

Rouatbi

et al. 2018

Libyan Journal of Medicine

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An obstructive ventilatory defect (OVD) is defined by a low forced expiratory volume/‘forced/slow’ vital capacity (FEV1/FVC) (e.g. 70%), moderate (60–69%), moderately severe (50–59%), severe (35–49%), and very severe (<35%) and GLI (FEV1Z-score): mild (≥ −2.0), moderate (−2.0 to −2.5), moderately severe (−2.5 to −3.0), severe (−3.0 to −4.0), and very severe (<−4.0). The frequencies of OVD were 14.4% (ATS/ERS method) and 10.5% (GLI method) (p < 0.05). Among the 103 participants having an OVD according to the two methods, the severity classification was mild (34.95% vs. 37.86%, p < 0.05), moderate (25.24% vs. 18.45%, p < 0.05), moderately severe (23.30% vs. 15.53%, p = 0.144), severe (9.71% vs. 20.39%, p < 0.05), and very severe (6.80% vs. 7.77%, p = 0.785), respectively for the ATS/ERS and GLI classifications. The two OVD definitions were not exchangeable. Moreover, the two grading severity systems misclassified the OVD grades.

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Classification of Airflow Limitation Based on z-Score Underestimates Mortality in Patients with Chronic Obstructive Pulmonary Disease

Abstract: In patients with COPD, the AL classification based on z-score predicts worse mortality than those based on percentage of predicted. It is possible that the z-score underestimates AL severity in patients older than 60 years of age with severe functional impairment.

Cited by 26 publications

References 28 publications

Comparison of pre‐ and post‐bronchodilator lung function as predictors of mortality: The HUNT Study

Comparison of pre‐ and post‐bronchodilator lung function as predictors of mortality: The HUNT Study

Predicting life expectancy of older people using respiratory symptoms and smoking status: Data from the Australian Longitudinal Study of Ageing

Defining and grading an obstructive ventilatory defect (OVD): ‘FEV₁/FVC lower limit of normal (LLN) vs. Z-score’ and ‘FEV₁ percentage predicted (%pred) vs. Z-score’

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Classification of Airflow Limitation Based on z-Score Underestimates Mortality in Patients with Chronic Obstructive Pulmonary Disease

Abstract: In patients with COPD, the AL classification based on z-score predicts worse mortality than those based on percentage of predicted. It is possible that the z-score underestimates AL severity in patients older than 60 years of age with severe functional impairment.

Cited by 26 publications

References 28 publications

Comparison of pre‐ and post‐bronchodilator lung function as predictors of mortality: The HUNT Study

Comparison of pre‐ and post‐bronchodilator lung function as predictors of mortality: The HUNT Study

Predicting life expectancy of older people using respiratory symptoms and smoking status: Data from the Australian Longitudinal Study of Ageing

Defining and grading an obstructive ventilatory defect (OVD): ‘FEV1/FVC lower limit of normal (LLN) vs. Z-score’ and ‘FEV1 percentage predicted (%pred) vs. Z-score’

Contact Info

Product

Resources

About

Defining and grading an obstructive ventilatory defect (OVD): ‘FEV₁/FVC lower limit of normal (LLN) vs. Z-score’ and ‘FEV₁ percentage predicted (%pred) vs. Z-score’