Predictive Value of Different Expressions of Forced Expiratory Volume in 1 Second (FEV1) for Adverse Outcomes in a Cohort of Adults Aged 80 and Older

An updated comparison of standard and novel FEV1 indices' association with all-cause mortality

RATIONALE

Current recommendations for defining FEV1 abnormalities are based on Z-score cutoffs. Alternative approaches may better correlate with patient-related outcomes, including mortality.

OBJECTIVE

This study evaluates the association between FEV1 value and mortality in six FEV1 indices in a large, U.S based cohort.

METHODS

This is a cohort of 2007-2012 National Health and Nutrition Examination Study (NHANES) participants with spirometry and linked mortality data through 2019. We transformed FEV1 values to the following indices: raw FEV1, FEV1-Z scores (FEV1-Z), FEV1-Percent Predicted (FEV1-PP), FEV1/Height2 (FEV1/Ht2), FEV1/Height3 (FEV1/Ht3), and FEV1-Q. We compared association with all-cause mortality between lowest and highest FEV1 deciles of each index using Cox Proportional Hazards models. Two sensitivity analyses were performed, one after applying NHANES sample weighting and one including lower quality spirometry. A subgroup analysis of participants with airflow obstruction, defined as FEV1/FVC ≤ LLN, was performed.

RESULTS

Of the 12,994 included participants, 971 (7.5%) had died. The majority (56.2%) were nonsmokers and 13.2% had an FEV1/FVC < LLN. When comparing the most to least severe deciles of FEV1, the indices with the largest magnitude unadjusted hazard ratios were FEV1/ht3 (HR 26.4, 95%CI 16.0-43.6), FEV1/ht2 (HR 21.8, 95%CI 13.8-34.7), FEV1-Q (HR 17.5, 95%CI 11.6-26.5), and FEV1 (HR 14.4, 95%CI 9.7-21.5). After adjusting for age, gender, and tobacco pack-years, FEV1/Ht3 (HR 4.9, 95%CI 2.6-9.3) and FEV1/Ht2 (HR 4.8, 95%CI 2.7-8.7) had the highest hazard ratios, however the confidence intervals had significant overlap with other indices. In adjusted analyses, the C-statistic (0.81) was the same across indices. Sensitivity and subgroup analyses yielded a similar pattern.

CONCLUSIONS

Reference-range-independent indices based on absolute FEV1 (raw FEV1, FEV1-Q, FEV1/Ht2, FEV1/Ht3) are equally or more strongly associated with mortality than reference-range- dependent FEV1 indices (FEV1-Z scores, FEV1-Percent Predicted) in a large U.S. cohort.

Pulmonary function tests: an integrated approach to interpreting results in the search for treatable traits

INTRODUCTION

Technological advances have led to the proliferation of lung function assessment techniques beyond spirometry in most countries. At the same time, new knowledge of respiratory physiology has allowed an expansion of lung function parameters, requiring an integrated approach to interpreting results.

AREAS COVERED

This review addresses the major pulmonary function tests (PFTs) used in clinical practice, new concepts regarding reference values, and reformulations of terminology for defining standards of lung function impairment. It highlights the complexities and nuances inherent in the interpretation of PFT parameters, particularly in light of recent updates from the European Respiratory Society/American Thoracic Society.

EXPERT OPINION

In a new paradigm, PFTs should be used to classify the pathophysiology of treatable traits rather than to diagnose respiratory disease, given the considerable variation in the clinical patterns of PFTs. It is necessary to look not only at lung mechanics but also at lung volume, gas transfer, and small airway involvement to capture as much information as possible. In this context, it is also important to understand that racial/ethnic differences in lung function are not due to biological differences but may reflect socioeconomic status and represent health disparities.

FEV1Q: a race-neutral approach to assessing lung function

BACKGROUND

Forced expiratory volume in 1 s quotient (FEV1Q) is a simple approach to spirometry interpretation that compares measured lung function to a lower boundary. This study evaluated how well FEV1Q predicts survival compared with current interpretation methods and whether race impacts FEV1Q.

METHODS

White and Black adults with complete spirometry and mortality data from the National Health and Nutrition Examination Survey (NHANES) III and the United Network for Organ Sharing (UNOS) database for lung transplant referrals were included. FEV1Q was calculated as FEV1 divided by 0.4 L for females or 0.5 L for males. Cumulative distributions of FEV1 were compared across races. Cox proportional hazards models tested mortality risk from FEV1Q adjusting for age, sex, height, smoking, income and among UNOS individuals, referral diagnosis. Harrell's C-statistics were compared between absolute FEV1, FEV1Q, FEV1/height2, FEV1 z-scores and FEV1 % predicted. Analyses were stratified by race.

RESULTS

Among 7182 individuals from NHANES III and 7149 from UNOS, 1907 (27%) and 991 (14%), respectively, were Black. The lower boundary FEV1 values did not differ between Black and White individuals in either population (FEV1 first percentile difference ≤0.01 L; p>0.05). Decreasing FEV1Q was associated with increasing hazard ratio (HR) for mortality (NHANES III HR 1.33 (95% CI 1.28-1.39) and UNOS HR 1.18 (95% CI 1.12-1.23)). The associations were not confounded nor modified by race. Discriminative power was highest for FEV1Q compared with alternative FEV1 approaches in both Black and White individuals.

CONCLUSIONS

FEV1Q is an intuitive and simple race-neutral approach to interpreting FEV1 that predicts survival better than current alternative methods.

Influences of Two FEV1 Reference Equations (GLI-2012 and GIRH-2017) on Airflow Limitation Classification Among COPD Patients

Objective

Methods

Results

Conclusion

ERS/ATS technical standard on interpretive strategies for routine lung function tests

BACKGROUND

Appropriate interpretation of pulmonary function tests (PFTs) involves the classification of observed values as within/outside the normal range based on a reference population of healthy individuals, integrating knowledge of physiological determinants of test results into functional classifications and integrating patterns with other clinical data to estimate prognosis. In 2005, the American Thoracic Society (ATS) and European Respiratory Society (ERS) jointly adopted technical standards for the interpretation of PFTs. We aimed to update the 2005 recommendations and incorporate evidence from recent literature to establish new standards for PFT interpretation.

METHODS

This technical standards document was developed by an international joint Task Force, appointed by the ERS/ATS with multidisciplinary expertise in conducting and interpreting PFTs and developing international standards. A comprehensive literature review was conducted and published evidence was reviewed.

RESULTS

Recommendations for the choice of reference equations and limits of normal of the healthy population to identify individuals with unusually low or high results are discussed. Interpretation strategies for bronchodilator responsiveness testing, limits of natural changes over time and severity are also updated. Interpretation of measurements made by spirometry, lung volumes and gas transfer are described as they relate to underlying pathophysiology with updated classification protocols of common impairments.

CONCLUSIONS

Interpretation of PFTs must be complemented with clinical expertise and consideration of the inherent biological variability of the test and the uncertainty of the test result to ensure appropriate interpretation of an individual's lung function measurements.

Reduced pulmonary function, low-grade inflammation and increased risk of total and cardiovascular mortality in a general adult population: Prospective results from the Moli-sani study

AIM

to investigate the relation of pulmonary function impairment with mortality and the possible mediation by low-grade inflammation in a general adult population.

METHODS

A prospective investigation was conducted on 14,503 individuals from the Moli-sani study (apparently free from lung disease and acute inflammatory status at baseline; 2005-2010). The 2012 Global Lung Function Initiative percent predicted (% pred) value of forced expiratory volume in the first second (FEV1), forced vital capacity (FVC), forced expiratory flow at 25-75% of FVC (FEF25-75) and FEV1 quotient (FEV1Q) index were used. C-reactive protein and blood cell counts were measured and a score of subclinical inflammation (INFLA-score) was calculated.

RESULTS

Over a median follow-up of 8.6y, 503 deaths (28.9% cardiovascular) were ascertained. Total mortality increased by 19% for each decrease in 1 standard deviation of FEV1% pred or FVC% pred (Hazard Ratio:1.19; 95% CI:1.11-1.28 and 1.19; 1.10-1.28, respectively). Comparable findings for FEV1Q (1.30; 1.15-1.47) were observed. A statistically significant increased risk in cardiovascular mortality of 23%, 32% and 49% was observed for 1 standard deviation decrease of FEV1% pred, FVC% pred and FEV1Q, respectively. INFLA-score mediated the association of FEV1% pred and FEV1Q with cardiovascular mortality by 22.3% and 20.1%, respectively. Subjects with FEV1, FVC lower than normal limit showed increased risk both in total and cardiovascular mortality. Abnormal FEF25-75 values were associated with 33% (1.33; 1.02-1.74) total mortality risk.

CONCLUSIONS

Obstructive lung function impairment was associated with decreased survival. Low-grade inflammation mainly mediated the association of FEV1 with cardiovascular mortality.

Reduction in TLco and survival in a clinical population

How best to express the level of lung gas transfer (TLco) function has not been properly explored. We used the most recent clinical data from 13 829 patients (54% male, 10% non-European ancestry), median age 60.5 years (range 20-97), median survival 3.5 years (range 0-20) to determine how best to express TLco function in terms of its relation to survival. The proportion of subjects of non-European ancestry with Global Lung Function Initiative (GLI) TLco z-scores above predicted was reduced but was significantly increased between -1.5 to -3.5 suggesting the need for ethnicity appropriate equations. Applying GLI FVC ethnicity methodology to GLI TLco z-scores removed this ethnic bias and was used for all subsequent analysis. TLco z-scores using the GLI equations were compared with Miller's US equations with median TLco z-scores being -1.43 and -1.50 for GLI and Miller equations respectively (interquartile range -2.8 to -0.3 and -2.4 to -0.7, respectively). GLI TLco z-scores gave the best Cox regression model for predicting survival. A previously proposed six-tier grading system for level of lung function did not show much separation in survival risk in the less severe grades. A new four-tier grading based on z-scores of -1.645, -3 and -5 showed better separation of risk with hazard ratio for all-cause mortality of 2.0, 3.4 and 6.6 with increasing severity. Using GLI FVC ethnicity methodology to GLI TLco predictions removed ethnic bias and may be the best approach until relevant datasets are available.

A comprehensive analysis of factors related to lung function in older adults: Cross-sectional findings from the Canadian Longitudinal Study on Aging

Maintenance of lung function is an often underappreciated, yet critical component of healthy aging. Given the unprecedented shift in the average age of Canadians over the next half century, it will be important to investigate the determinants of lung function in the elderly. In the following study, we estimated the association between lung function and a broad array of factors related to sociodemographics, lifestyle, chronic medical conditions and psychosocial factors in older adults aged 45-86 years old using cross-sectional data from the Canadian Longitudinal Study of Aging (n = 21,338). In addition to examining the entire cohort, we also performed stratified analyses within men/women, adults aged 45-64/65+, and healthy/comorbid. In multivariable regression, our explanatory factors (excluding age, sex, height and ethnicity) were able to explain 17% and 11% of the total variance in FEV₁ and FEV₁/FVC, respectively. Notable and significant contributions were observed for respiratory disease, smoking, obesity, income, and physical activity, while psychosocial factors mainly exhibited non-significant associations. Generally, these associations were stronger for males than females, and adults 65 and older as compared to those aged 45-64. Our findings indicate that there are pervasive and generally under-recognized sociodemographic and lifestyle factors that exhibit significant associations with FEV₁ and FEV₁/FVC in older adults. While implication of causality in these relationships is not possible due to the cross-sectional nature of the study, future work aiming to investigate determinants of lung health in older adults may choose to target these factors, given that many are modifiable.

How to Stage Airflow Limitation in Stable Chronic Obstructive Pulmonary Disease Male Patients?

No study has evaluated the utility of different classifications of chronic obstructive pulmonary disease (COPD) airflow limitation (AFL) in terms of the refined “ABCD” classification of the Global Initiative for Chronic Obstructive Lung Disease (GOLD) or in terms of the impacts on quality of life. This study aimed to compare some relevant health outcomes (i.e., GOLD classification and quality-of-life scores) between COPD patients having “light” and “severe” AFL according to five COPD AFL classifications. It was a cross-sectional prospective study including 55 stable COPD male patients. The COPD assessment test (CAT), the VQ11 quality-of-life questionnaire, a spirometry, and a bronchodilator test were performed. The patients were divided into GOLD “A/B” and “C/D.” The following five classifications of AFL severity, based on different post-bronchodilator forced expiratory volume in 1 s (FEV₁) expressions, were applied: FEV_1%pred: “light” (≥50), “severe” (<50); FEV_1z-score: “light” (≥−3), “severe” (<−3); FEV₁/height²: “light” (≥0.40), “severe” (<0.40); FEV₁/height³: “light” (≥0.29), “severe” (<0.29); and FEV_1Quotient: “light” (≥2.50), “severe” (<2.50). The percentages of the patients with “severe” AFL were significantly influenced by the applied classification of the AFL severity (89.1 [FEV_1z-score], 63.6 [FEV_1%pred], 41.8 [FEV₁/height³], 40.0 [FEV_1Quotient], and 25.4 [FEV₁/height²]; Cochrane test = 91.49, df = 4). The CAT and VQ11 scores were significantly different between the patients having “light” and “severe” AFL. In GOLD “C/D” patients, only the FEV_1Quotient was able to distinguish between the two AFL severities. To conclude, the five classifications of COPD AFL were not similar when compared with regard to some relevant health outcomes.

Predictive Accuracy of Frailty Tools for Adverse Outcomes in a Cohort of Adults 80 Years and Older: A Decision Curve Analysis

OBJECTIVES

To compare the predictive performance of 3 frailty identification tools for mortality, hospitalization, and functional decline in adults aged ≥80 years using risk reclassification statistics and decision curve analysis.

DESIGN

Population-based, prospective cohort.

SETTING

BELFRAIL study, Belgium.

PARTICIPANTS

560 community-dwelling adults aged ≥80 years.

MEASUREMENTS

Frailty by Cardiovascular Health Study (CHS) phenotype, Longitudinal Aging Study Amsterdam (LASA) markers, and Groeningen Frailty Indicator (GFI); mortality until 5.1 ± 0.25 years from baseline and hospitalization until 3.0 ± 0.25 years; and functional status assessed by activities of daily living at baseline and after 1.7 ± 0.21 years.

RESULTS

Frailty prevalence was 7.3% by CHS phenotype, 21.6% by LASA markers, and 22% by GFI. Participants determined to be frail by each tool had a significantly higher risk for all-cause mortality and first hospitalization. For functional decline, only frail by GFI had a higher adjusted odds ratio. Harrell 's C-statistic for mortality and hospitalization and area under receiver operating characteristic curve for functional decline were similar for all tools and <0.70. Reclassification statistics showed improvement only by LASA markers for hospitalization and mortality. In decision curve analysis, all tools had higher net benefit than the 2 default strategies of "treat all" and "treat none" for mortality risk ≥20%, hospitalization risk ≥35%, and functional decline probability ≥10%, but their curves overlapped across all relevant risk thresholds for these outcomes.

CONCLUSIONS AND IMPLICATIONS

In a cohort of adults aged ≥80 years, 3 frailty tools based on different conceptualizations and assessment sources had comparable but unsatisfactory discrimination for predicting mortality, hospitalization, and functional decline. All showed clinical utility for predicting these outcomes over relevant risk thresholds, but none was significantly superior. Future research on frailty tools should include a focus on the specific group of adults aged ≥80 years, and the predictive accuracy for adverse outcomes of different tools needs a comprehensive assessment that includes decision curve analysis.

Relationship between peak expiratory flow and incidence of frailty, deaths and falls among nursing home residents: Results of the SENIOR cohort

OBJECTIVE

To correlate peak expiratory flow (PEF) with the incidence of frailty, deaths and falls among nursing home residents.

METHODS

This is a 1-year longitudinal analysis performed on the clinical data of the SENIOR cohort. PEF, measured by peak flow meter, was considered as "low" when the observed value was ≤80% of the theoretical value. Physical capacity was evaluated using Short Physical Performance Battery, balance and gait using Tinetti test and muscle strength using a dynamometer. The incidence of frailty was defined as the transition from a "robust" or "prefrail" status to a "frail" status following Fried's criteria. Deaths and falls were also collected.

RESULTS

Among 646 subjects included at baseline (83.2 ± 9 years and 72.1% women), 297 (45.7%) displayed a low PEF. In this subgroup, physical capacity (p-values from 0.01 to <0.001), muscle strength (p < 0.001), balance and gait score (p < 0.001) were significantly lower compared to subjects displaying normal PEF. Subjects who became frail after one year displayed a lower % of the theoretical PEF value compared to those that did not (88.52 ± 45.06 vs 102.78 ± 50.29, respectively, p = 0.03). After adjustment for potential confounding variables (calf circumference, Tinetti test, SPPB test and handgrip strength), PEF was no longer associated with the occurrence of frailty. There was no association between PEF and mortality and falls.

CONCLUSION

In a nursing home setting, PEF is not an independent factor associated with the incidence of frailty, deaths and falls.

Prognostic value of short-term decline of forced expiratory volume in 1 s over height cubed (FEV1/Ht3) in a cohort of adults aged 80 and over

BACKGROUND

Forced expiratory volume in 1 s over height cubed (FEV₁/Ht³) is an FEV₁ expression that uses no reference values and is independently associated with adverse outcomes in older adults. No studies have reported on the prognostic value of its decline over time in adults aged 80 and over.

AIM

To investigate the prognostic value of FEV₁/Ht³ decline for adverse outcomes in a cohort of adults aged 80 and over.

METHODS

328 community-dwelling adults aged 80 and over of the BELFRAIL prospective cohort had two valid FEV₁ measurements as part of their comprehensive geriatric assessment at baseline and follow-up (after 1.7 ± 0.21 years). Kaplan-Meier survival curves, Cox and logistic multivariable regression, assessed association of excessive decline of FEV₁/Ht³ (lowest quintile of percentage change) with all-cause mortality (3 years after follow-up assessment), time to first hospitalization (1 year), and new/ worsened disability in activities of daily living (ADL) at the follow-up assessment.

RESULTS

Participants with excessive FEV₁/Ht³ decline had increased adjusted hazard ratio for all-cause death 1.61 (95% CI 1.01-2.55) and first hospitalization 1.71 (1.08-2.71) and increased odds ratio for new/worsened ADL disability at follow-up 2.02 (1.10-3.68) compared to the rest of the study population.

CONCLUSIONS

Excessive, short-term decline in FEV₁/Ht³ was independently associated with all-cause mortality, time to first, unplanned hospitalization, and ADL disability in a cohort of adults aged 80 and over. This FEV₁ expression should be further investigated in studies of longitudinal FEV₁ change in older adults.

Comparison of different staging methods for COPD in predicting outcomes

Chronic obstructive pulmonary disease (COPD) is commonly staged according to the percentage of predicted forced expiratory volume in 1 s (FEV₁ % pred), but other methods have been proposed. In this study we compared the performance of seven staging methods in predicting outcomes.We retrospectively studied 296 COPD outpatients. For each patient the disease severity was staged by separately applying the following methods: the criteria proposed by the Global Initiative for Chronic Obstructive Lung Disease (GOLD), quartiles of FEV₁ % pred and z-score of FEV₁, quartiles and specified cut-off points of the ratio of FEV₁ over height squared ((FEV₁·Ht^-2)_A and (FEV₁·Ht^-2)_B, respectively), and quartiles of the ratio of FEV₁ over height cubed (FEV₁·Ht^-3) and of FEV₁ quotient (FEV₁Q). We evaluated the performance of these methods in predicting the risks of severe acute exacerbation and all-cause mortality.Overall, staging based on the reference-independent FEV₁Q performed best in predicting the risks of severe acute exacerbation (including frequent exacerbation) and mortality, followed by (FEV₁·Ht^-2)_B The performance of staging methods could also be influenced by the choice of cut-off values. Future work using large and ethnically diverse populations to refine and validate the cut-off values would enhance the prediction of outcomes.