A Race-neutral Approach to the Interpretation of Lung Function Measurements

Geographical variation in lung function: Results from the multicentric cross-sectional BOLD study

Spirometry is used to determine what is "unusual" lung function compared with what is "usual" for healthy non-smokers. This study aimed to investigate regional variation in the forced vital capacity (FVC) and in the forced expiratory volume in one second to FVC ratio (FEV1/FVC) using cross-sectional data from all 41 sites of the multinational Burden of Obstructive Lung Disease study. Participants (5,368 men; 9,649 women), aged ≥40 years, had performed spirometry, had never smoked and reported no respiratory symptoms or diagnoses. To identify regions with similar FVC, we conducted a principal component analysis (PCA) on FVC with age, age2 and height2, separately for men and women. We regressed FVC against age, age2 and height2, and FEV1/FVC against age and height2, for each sex and site, stratified by region. Mean age was 54 years (both sexes), and mean height was 1.69 m (men) and 1.61 m (women). The PCA suggested four regions: 1) Europe and richer countries; 2) the Near East; 3) Africa; and 4) the Far East. For the FVC, there was little variation in the coefficients for age, or age2, but considerable variation in the constant (men: 2.97 L in the Far East to 4.08 L in Europe; women: 2.44 L in the Far East to 3.24 L in Europe) and the coefficient for height2. Regional differences in the constant and coefficients for FEV1/FVC were minimal (<1%). The relation of FVC with age, sex and height varies across and within regions. The same is not true for the FEV1/FVC ratio.

Respiratory symptoms in preserved ratio impaired spirometry: Link to comorbidities and increased mortality risk

BACKGROUNDX

Respiratory symptoms are frequently observed in subjects with Preserved Ratio Impaired Spirometry (PRISm); however, their association with comorbidities and mortality in this population remains poorly understood.

METHODS

Data from the National Health and Nutrition Examination Survey (2007-2012) were analyzed. Logistic regression was used to assess the association between respiratory symptoms and comorbidities, while Cox regression was applied to evaluate mortality risks.

RESULTS

This study included 5612 adults aged 40 years and older with normal spirometry and 754 participants with PRISm. Among the PRISm group, 331 subjects (43.8 %) reported one or more respiratory symptoms. Compared to individuals with normal spirometry, PRISm subjects with respiratory symptoms exhibited a significantly higher prevalence of comorbidities, including hypertension, diabetes, angina, myocardial infarction, heart failure, and stroke, as well as increased risks of all-cause and cardiovascular mortality. In contrast, PRISm without respiratory symptoms was primarily associated with diabetes and an elevated mortality risk. When comparing PRISm subjects with and without respiratory symptoms, those with symptoms had a markedly higher prevalence of hypertension (OR 1.10, 95 % CI: 1.08-1.11), myocardial infarction (OR 5.75, 95 % CI: 2.25-14.67), heart failure (OR 5.52, 95 % CI: 2.50-12.19), and cancer (OR 2.34, 95 % CI: 1.12-4.86). Additionally, PRISm subjects with respiratory symptoms faced a significantly elevated risk of cardiovascular mortality (HR 1.55, 95 % CI: 1.38-1.74).

CONCLUSIONS

Respiratory symptoms were associated with a significantly higher burden of comorbidities and an increased risk of cardiovascular mortality in PRISm subjects.

Development and validation a nomogram to predict long-term mortality risks of PRISm and mild-to-moderate COPD based on NHANES 2007-2012

Chronic Obstructive Pulmonary Disease (COPD) can be prevented in the pre-clinical and early stages. However, very limited prediction models of COPD focus on Preserved Ratio Impaired spirometry (PRISm) and early stages. To fill this gap, this study aimed to develop and validate a nomogram to predict long-term mortality risks of PRISm and early COPD. We obtained data of participants in the US National Health and Nutrition Examination Surveys 2007-2012 and the available mortality follow-up data from the date of survey participation to Dec 31, 2019. The study population (n = 1043) was randomly divided into training and validation datasets at a ratio of 7:3. The cox proportional hazards model was applied to select significant prognostic risk factors of COPD in the training dataset. Besides, the predictive power and clinical usage value were assessed by the area under time dependent receiver operating characteristic curve (time-dependent AUROC), calibration curves and decision curve analysis (DCA). Moreover, directed acyclic graph (DAG) was utilized to plot causal associations between risk factors and mortality. We developed an accurate and easy to use nomogram using six predictors (age, passive smoking, alkaline phosphotase, gamma glutamyl transferase, lactate dehydrogenase, potassium). The nomogram had satisfactory predictive performance, as the time-dependent AUROC with 95% confidence interval (CI) at 7.5 years was 0.78 (0.69-0.84) and 0.80 (0.67, 0.87) in the training and validation datasets, respectively. The calibration curves and DCA also showed that the nomogram had good clinical usage value. Compared with the low-risk groups, the Hazard Ratio in the high-risk group was 2.25 (95% CI 1.29-3.94) in the validation datasets, respectively. DAG shown that there had directly associations of passive smoking and lactate dehydrogenase with all-cause mortality. The nomogram has the potential to identify high-risk populations in the pre-clinical and early stages of COPD.

Comparison of PRISm phenotypes on cardiovascular disease risk and spirometry trajectory: A large prospective cohort study

BACKGROUND

Emerging evidence indicated an association between preserved ratio impaired spirometry (PRISm) and cardiovascular disease (CVD) outcomes. However, the relationship between baseline characteristics, transitional trajectories of PRISm phenotypes, and CVD outcomes remains underexplored.

METHODS

This study included 285,049 participants with spirometry measurements between 2006 and 2010, excluding those with preexisting CVD, including heart failure (HF), coronary heart disease (CHD), stroke, and those with airway obstruction (AO). Among them, 23,650 participants with follow-up spirometry (2014-2020) were analyzed for further pulmonary function transitions study.

RESULTS

At baseline, restrictive (vs. non-restrictive) PRISm showed higher multivariate adjusted hazard ratios (HRs) of 1.20 (95 % confidence interval [CI], 1.03-1.46) for HF, 1.05 (95 % CI, 1.01-1.10) for stroke, and overall CVD events (HR = 1.10, 95 % CI = 1.00-1.23). For spirometry transition trajectory, restrictive PRISm tended to remain stable, while non-restrictive PRISm often transitioned to other status over time. Moreover, normal to restrictive PRISm (HR = 1.71; 95 % CI, 1.21-2.43), and normal to AO (HR = 1.45; 95 % CI, 1.05-2.00) were associated with higher CVD risk compared to consistently normal spirometry.

CONCLUSIONS

Restrictive PRISm is more strongly associated with the development of CVD compared to non-restrictive PRISm and follows a distinct spirometry trajectory. Early intervention aimed at improving PRISm lung function may help mitigate the incidence of cardiovascular events.

Mucus Plug Score Predicts Clinical and Pulmonary Function Response to Biologic Therapy in Patients With Severe Asthma

BACKGROUND

Mucus plugging has been identified as an important feature of severe asthma contributing to airway obstruction and disease severity. Recently, improvement in mucus plugging has been found on treatment with several biologic therapies.

OBJECTIVES

To analyze associations of baseline characteristic with the mucus plugging score (MPS) and to determine whether the MPS at baseline predicts the clinical and functional response to biologic treatment in patients with severe asthma.

METHODS

We retrospectively analyzed biologic-naive patients with a suitable computed tomography scan available at baseline. We calculated the MPS and analyzed correlations with baseline parameters and improvements in biomarkers, pulmonary function, and clinical parameters after 4 months of biologic therapy.

RESULTS

We included 113 patients in the baseline cohort, 101 patients of whom had sufficient data after 4 months of biologic therapy for the follow-up analysis. Computed tomography showed mucus plugging in 77% of patients (median MPS, 4). Multivariate regression analysis showed a correlation of MPS with lower FEV1 (ρ = -0.24; P = .009) and diffusing capacity for carbon monoxide (ρ = -0.26; P = .01), and higher FeNO (ρ = .36; P = .0003) at baseline. Patients received treatment with anti-IgE (8.8%), anti-IL-5 (27.4%), anti-IL-5R (37.2%), anti-IL-4R (25.7%), and anti-thymic stromal lymphopoietin (0.9%) in clinical routine. Baseline MPS correlated with improvements in FEV1 (β = 0.72; P = .01) and Asthma Control Test (β = 0.24; P = .001) in multivariate regression analysis.

CONCLUSION

Our study suggests that a higher MPS correlates with worse pulmonary function at baseline but also predicts a larger clinical and pulmonary function response to biologic therapies in severe asthma.

Update in paediatric asthma

PURPOSE OF REVIEW

The field of paediatric asthma is rapidly moving, with the advent of new biologicals for severe asthma and increased understanding of preschool wheeze amongst other developments and insights.

RECENT FINDINGS

There is increasing evidence of efficacy in children for biologics directed against Type 2 inflammation (especially mepolizumab and dupilumab) as well encouraging evidence that Tezepelumab may be effective against Type 2 low phenotypes. The importance of airway remodelling and infection in the pathophysiology of preschool wheeze is increasingly appreciated. The treatment of preschool wheeze is moving from symptom-based to biomarker driven therapies. Other important areas are prediction of risk of asthma attacks, the SMART regime, the importance of climate change and reducing greenhouse gas emissions from inhalers while ensuring adequate therapy for young children, the association of early adverse environmental factors including childhood poverty and deprivation and the switch to race-neutral lung function equations.

SUMMARY

We are increasingly moving towards personalized medicine and the use of biomarkers to guide treatment of wheeze at all ages, but we need to move from counting cells to determining their functional status. Airway wall structural changes rather than inflammation may drive the progression of preschool wheeze to school age asthma.

The Effect of Being Born Moderate to Late Preterm on Lung Function and Respiratory Morbidity at 9 to 10 Years of Age

Rationale: The effect of moderate to late preterm (MLP) birth (32-36 completed weeks' gestation) on childhood respiratory health is unclear. Objectives: To assess the effect of being born MLP, compared with being born at term (≥37 completed weeks' gestation), on lung function and respiratory morbidity at 9-10 years of age. Methods: A prospective cohort study was conducted among children born MLP or at term at the Royal Women's Hospital (Victoria, Australia). Participants completed pre and postbronchodilator spirometry, measurement of diffusing capacity of the lung for carbon monoxide, plethysmography, and multiple-breath washout at 9-10 years of age. Parents completed the ISAAC (International Study of Asthma and Allergies in Childhood) questionnaire. Mean differences in z-scores of lung function outcomes and risk ratio for ISAAC outcomes between those born MLP and those born at term were estimated using regression models with adjustment for potential confounding. Multiple imputation was used to handle missing data. Results: A total of 148 of 201 children born MLP and 120 of 201 term-born control subjects were assessed at 9-10 years. Compared with control subjects, children born MLP had lower mean z-scores for forced expiratory volume in 1 second (mean difference, -0.35 [95% confidence interval (CI), -0.61 to -0.08]), ratio of forced expiratory volume in 1 second to forced vital capacity (mean difference, -0.29 [95% CI, -0.58 to -0.01]), forced expiratory flow at 25-75% of forced vital capacity (-0.33 [95% CI, -0.62 to -0.04]), and diffusing capacity of the lung for carbon monoxide (-0.24 [95% CI, -0.45 to -0.03]). Participants born MLP had higher risk of experiencing asthma symptoms (risk ratio, 1.52 [95% CI, 1.08-2.14]). Conclusions: Children born MLP have lower lung function and increased risk of exhibiting asthma symptoms compared with term-born peers at 9-10 years. Such findings at the end of the first decade of life may portend adverse consequences for respiratory health in adulthood.

Clinical interpretation of DLCO and KCO: From rationale to clinical and research applications

Single-breath methods for measuring the diffusing capacity of the lung for carbon monoxide (DLCO), Krogh's constant for CO (KCO), and alveolar volume (VA) play clinically vital roles in assessing lung diffusion. While the methodology is valid for the kinetics of normal lungs, appropriate interpretations are necessary for lung diseases involving emphysema and/or ventilation heterogeneity. Severe airflow limitations and ventilation heterogeneities lead to the underestimation of lung volume, calculated as VA, relative to the total lung capacity assessed using the helium closed-circuit method. Notably, the relative increase in KCO (DLCO/VA) compared to DLCO-resulting from increased blood flow per alveolar-capillary unit in small lungs with fibrosis-is a distinct feature of interstitial lung disease. Therefore, the combined assessment of DLCO and KCO may help elucidate the pathophysiology of emphysema and/or pulmonary fibrosis. This review aims to explain Krogh's equation, the difference between DLCO and D'LCO, the kinetics, and the clinical application of DLCO (or D'LCO) and KCO. Pulmonary function varies among ethnicities and races; thus, reference equations derived while considering anthropological traits are necessary. Additionally, the link between physiological theory, radiological findings, and the clinical relevance of DLCO and KCO is discussed, mostly based on Japanese studies. In this review, DLCO obtained from the single-breath method is referred to as "D'LCO"; however, for convenience, it is described as "DLCO," with the term "D'LCO" used only where necessary.

Diagnosing Asthma in Children

Despite being the most common chronic lung disease in children, asthma continues to be frequently misdiagnosed in the pediatric population. The recommendations to establish a diagnosis of asthma in school-aged children have evolved over time, but there are still important discrepancies between published guidelines. Furthermore, preschool-aged children are often unable to perform objective testing, so the diagnosis of asthma remains a clinical one in the first several years of life, and there is still debate on the criteria and nomenclature to be used in this age group. In this review, we first discuss the definition and misdiagnosis of asthma in children. We then assess and compare published guidelines that outline how to establish the diagnosis of asthma in school-aged children. We also discuss the necessary steps to diagnose preschool-aged children with this disease. Last, we outline unanswered questions and opportunities for research in this field.

Health disparities and associated social determinants of health in interstitial lung disease: a narrative review

BACKGROUND

Health disparities are prevalent across respiratory diseases. Social determinants of health are closely associated with health disparities and account for between 30% and 55% of all health outcomes. In people with interstitial lung disease (ILD), disparities have the potential to significantly impact access to care and health outcomes along many stages of the disease journey.

AIM

This review aimed to provide an overview of health disparities in ILD, focusing on the determinants of health and access to care from diagnosis to end of life and to report on some approaches being proposed to address these disparities.

METHODS

A narrative review of the literature was undertaken using three electronic databases (Ovid Embase, Medline and CINAHL) from inception to May 2024. Disparities and social determinants were mapped to the domains of the Dahlgren-Whitehead model of social determinants of health.

RESULTS

A total of 31 studies were eligible for inclusion. Common disparities identified included differences in antifibrotic utilisation, representation in clinical trials, access to ILD care and lung transplantation waiting lists. Associated social determinants included race/ethnicity, gender, geography and socioeconomic status. Paradoxically, telehealth technology and utilisation have the potential to improve access to diagnostic and treatment options for marginalised communities but may exacerbate disparities for those with lower digital literacy and access.

CONCLUSION

Reducing health disparities in ILD will require an awareness and understanding of the root cause of the disparities at both the individual and societal level in order to develop effective interventions that improve access to care for all living with ILD.

Lung Function Trajectory Using Race-Specific vs Race-Neutral Global Lung Function Initiative Coefficients

Importance

The use of race-based coefficients in pulmonary function testing has led to the recent development of the race-neutral Global Lung Function Initiative (GLI) reference equation (hereafter GLI Global). The performance of GLI Global in comparison to race-adjusted coefficients (hereafter GLI 2012) has not been well characterized.

Objective

To compare the implications of GLI 2012 vs GLI Global reference equations for lung function trajectory.

Design, Setting, and Participants

This cohort study at Massachusetts General Hospital analyzed data of patients aged 18 to 95 years who completed spirometry testing between January 1, 1997, and December 31, 2020. Data analysis was performed from January 2023 to November 2024.

Exposures

GLI Global and GLI 2012 reference equations to define lung function.

Main Outcomes and Measures

Proportion of patients with recategorized lung function (FEV1 and FVC) based on the 2 reference equations and their lung function trajectory over time. Lung function metrics included forced expiratory volume in the first second of expiration (FEV1), forced vital capacity (FVC), and FEV1 to FVC ratio. The z scores for FEV1 and FVC were calculated using the GLI 2012 and GLI Global reference equations, with a score lower than -1.64 considered abnormal. Patients were categorized into 1 of 4 groups based on their z scores: normal to normal (normal z score on both equations); abnormal to normal (abnormal z score based on GLI 2012 equations but normal based on the GLI Global equation); normal to abnormal (normal z score on GLI 2012 equations but abnormal on the GLI Global equation); and abnormal to abnormal (abnormal z score on both equations).

Results

The sample included a total of 24 662 patients (988 Black [4.0%] and 22 297 White [90.4%] patients; 13 108 women [53.2%]) with a mean (SD) age of 57.6 (15.7) years who completed a median (IQR) of 3.0 (2.0-5.0) sets of spirometry over a median (IQR) of 2.6 (0.8-6.6) years between 1997 and 2020. Among Black patients, 190 (19.2%) had either their FEV1 or FVC recategorized from normal to abnormal using the GLI Global reference equation. The subset of Black patients whose lung function was recategorized from normal to abnormal exhibited FEV1 decline (-2.06%; 95% CI, -3.47% to -0.64%; P = .56) that was similar to decline in Black patients whose lung function was characterized as abnormal (-1.89%; 95% CI, -2.58% to -1.19%; P = .84) using both the GLI Global and GLI 2012 reference equations. Among White patients, 3348 (15.0%) had either their FEV1 or FVC recategorized from abnormal to normal using the GLI Global equation. FEV1 decline in these patients (-1.82%; 95% CI, -2.55% to -1.08%; P = .70) was similar to the decline in White patients with normal spirometry (-1.97%; 95% CI, -2.26% to -1.69%; P = .70) regardless of the reference equation used. Patterns in FVC trajectory among both Black and White participants were not consistent among participants whose spirometry was recategorized between normal and abnormal compared with those whose spirometry remained normal or remained abnormal regardless of the reference equation used.

Conclusions and Relevance

This cohort study found that Black patients whose lung function was recategorized from normal to abnormal using the GLI Global reference equation exhibited FEV1 decline similar to that in Black patients whose lung function was classified as abnormal regardless of which equation was used. This finding suggests that a race-neutral approach to spirometry interpretation may allow a more accurate identification of lung pathology in Black patients.

Brief Report: The Implications of Removing Race From Interpretation of Pulmonary Function Among Persons With or Without HIV

BACKGROUND

Studies suggest that the use of race-specific pulmonary function reference equations may obscure racial inequities in respiratory health. Whether removing race from the interpretation of pulmonary function would influence analyses of HIV and pulmonary function is unknown.

SETTING

Pulmonary function measurements from 1067 men (591 with HIV) in the Multicenter AIDS Cohort Study and 1661 women (1175 with HIV) in the Women's Interagency HIV Study were analyzed.

METHODS

Percent-of-predicted values for spirometry and single-breath diffusing capacity of carbon monoxide (DLCO) measurements were generated with race-specific reference equations derived from the National Health and Nutrition Examination Survey and with the race-neutral application of reference equations derived from the Global Lung Function Initiative database. Regression models were used to evaluate the association between HIV and percent-of-predicted measures of pulmonary function. Alpaydin's F test was used to compare how well these values predicted self-reported respiratory health-related quality of life.

RESULTS

Persons with HIV were observed to have significantly lower percent-of-predicted diffusing capacity for carbon monoxide (DLCO) than those without HIV but no significant differences in spirometric measures of pulmonary function, regardless of whether a race-specific or race-neutral approach was used. Among men, but not women, the race-neutral application of reference equations to generate percent-of-predicted DLCO values performed better for predicting respiratory-related quality of life.

CONCLUSIONS

The race-neutral application of pulmonary function reference equations continues to identify lung function impairment in persons with or at risk for HIV and, for DLCO, may be superior to the use of race-specific reference equations in identifying clinically relevant impairments.

The use of forced oscillation technique in children with restrictive physiology

The forced oscillation technique (FOT) may not identify lung function abnormalities in children with restrictive physiology. FOT findings correlate poorly with spirometry and plethysmography testing in children with diffuse parenchymal lung disease. https://bit.ly/4h4liIh.

Phenotypes and Trajectories of Tobacco-exposed Persons with Preserved Spirometry: Insights from Lung Volumes

Rationale: Among tobacco-exposed persons with preserved spirometry (TEPSs), we previously demonstrated that different lung volume indices-specifically, elevated total lung capacity (TLC) versus elevated ratio of functional residual capacity to TLC (FRC/TLC)-identify different lung disease characteristics in the COPDGene cohort. Objective: We sought to determine differential disease characteristics and trajectories associated with lung volume indices among TEPSs in the SPIROMICS cohort. Methods: We categorized TEPSs (n = 814) by tertiles (low, intermediate, and high) of TLC or residual volume-to-TLC ratio (RV/TLC) derived from baseline computed tomography images and then examined clinical and spirometric disease trajectories in mutually exclusive categories of participants with high TLC without high RV/TLC ([TLC]high) versus high RV/TLC without high TLC ([RV/TLC]high). We examined differences in computed tomography-measured emphysema (Hounsfield units [HU] ⩽-950; parametric response mapping [PRM] of emphysema), air trapping (HU⩽-856; PRM of functional small airway disease; a disease probability measure for non-emphysematous gas trapping), airway geometry (the mean square root of wall area of a hypothetical airway with 10 mm internal perimeter), respiratory symptoms (on the modified Medical Research Council Dyspnea Scale; COPD Assessment Test [CAT]; St. George's Respiratory Questionnaire [SGRQ]; and Short Form-12 [SF12]), and outcomes (annualized exacerbation rate) between the two categories at baseline and over follow-up time up to 8.5 years, using regression modeling adjusted for age, sex, height, weight, and smoking status (current vs. former smoker) and burden (pack-years). Results: In TEPSs, the pattern of spirometric disease progression differed between participants with [TLC]high and those with [RV/TLC]high: There was increased forced vital capacity with stable forced expiratory volume in 1 second in participants with [TLC]high, versus unchanged forced vital capacity but nominally decreased forced expiratory volume in 1 second in those with [RV/TLC]high. Compared with participants with [TLC]high, TEPSs with [RV/TLC]high had less emphysema (by HU ⩽-950) but more airway disease (by HU ⩽-856; PRM of functional small airway disease; disease probability measure for gas trapping, and mean square root of wall area of a hypothetical airway with 10 mm internal perimeter), more respiratory symptoms (on the modified Medical Research Council Dyspnea Scale, CAT, SGRQ, and SF12), and more severe exacerbations at baseline. Over an average follow-up of 4.1 ± 2.4 years (range = 0.5-8.5 yr), TEPSs with [RV/TLC]high also had a higher likelihood of developing more severe spirometric disease (preserved ratio impaired spirometry or Global Initiative for Chronic Obstructive Lung Disease Classification 2) and worsening of their respiratory symptoms (on the CAT and SGRQ). Although the incidence rates of respiratory exacerbations, hospitalizations, and mortality were not significantly different between the two categories over the follow-up period, TEPSs with [RV/TLC]high were more likely to have been prescribed a respiratory inhaler at their last follow-up visit. Conclusions: In these TEPSs from the SPIROMICS cohort, lung volume stratification by TLC versus RV/TLC identifies two pre-COPD phenotypes with distinct respiratory symptoms, radiographic features, and clinical trajectories. The characteristics of these pre-COPD phenotypes match those previously described in the COPDGene cohort using TLC versus FRC/TLC stratification.

Online database of clinical algorithms with race and ethnicity

Some clinical algorithms incorporate an individual's race, ethnicity, or both as an input variable or predictor in determining diagnoses, prognoses, treatment plans, or risk assessments. Inappropriate use of race and ethnicity in clinical algorithms at the point of care may exacerbate health disparities and promote harmful practices of race-based medicine. Using database analysis primarily, we identified 42 risk calculators that use race and ethnicity as predictors, five laboratory test results with reference ranges that differed based on race and ethnicity, one therapy recommendation based on race and ethnicity, 15 medications with race- and ethnicity-based initiation and monitoring guidelines, and five medical devices with differential racial and ethnic performances. Information on these clinical algorithms is freely available at https://www.clinical-algorithms-with-race-and-ethnicity.org/ . This resource aims to raise awareness about the use of race and ethnicity in clinical algorithms and track progress toward eliminating their inappropriate use. The database is actively updated to include clinical algorithms that were missed and additional characteristics of these algorithms.

Risk factors for lung cancer in never-smokers: Multi-cohort study

Background

If lung cancer in never-smokers was a single disease entity, it would be the sixth most commonly occurring malignancy. Despite the population impact, its risk factors are poorly understood owing to a dearth of larger-scale, well-characterised studies.

Methods

We pooled individual-participant data from 18 prospective cohort studies comprising 91,588 never smokers (55,452 women) aged 16-102 years at study induction. Participants were linked to national death registries.

Results

A maximum of 17 years follow-up (mean 9.7) gave rise to 85 lung cancer deaths. Of the 19 potential determinants captured at baseline, only being older age (hazard ratio; 95% confidence interval per 10 year increase: 2.45; 2.11, 2.85), male (2.25; 1.46, 3.48), and having a high fruit and vegetable intake (2.29; 1.25, 4.17) were associated with elevated rates of lung cancer in this never-smoking group. No other substantial relationships were detected.

Conclusions

Despite the number and breadth of potential risk factors featured in this multi-cohort study, there was no clear suggestion of new determinants of lung cancer in never-smokers.

Impact

Our findings point to the need to explore the influence of risk factors additional to those included herein, particular in the field of genetics. Our unlikely finding for fruit and vegetable consumption warrants further testing.

Association between e-cigarette exposure and ventilation homogeneity in young adults: a cross-sectional study

BACKGROUND

The number of young people who use e-cigarettes is rising. It remains unclear whether e-cigarette use impairs lung function. We aimed to compare ventilation distribution between young adults exposed to e-cigarettes and an unexposed group.

METHODS

Study participants included otherwise healthy young adults (18-24 years) who self-reported e-cigarette use and unexposed participants who had no history of e-cigarette, tobacco or cannabis exposure. Exposure to e-cigarettes was defined using three measures: 1) ever-exposed, 2) daily use and 3) puff frequency, which includes none (unexposed), minimal (<2 puffs·h-1), moderate (3-4 puffs·h-1) and heavy (≥5 puffs·h-1). Ventilation distribution was measured using the multiple-breath washout test and reported as lung clearance index (LCI).

RESULTS

A total of 93 participants were recruited; 38 unexposed and 41 exposed participants had LCI measures. The exposed group consisted predominately of participants who used flavoured e-liquids (94.5%) that contained nicotine (93.5%). The magnitude and direction of the difference in LCI across the exposure definitions was similar. Compared with the unexposed group, in the unadjusted models LCI was higher in those with any e-cigarette use (mean difference 0.15, 95% CI -0.004-0.31), daily users (mean difference 0.10, 95% CI -0.08-0.28) and heavy users (mean difference 0.22, 95% CI 0.03-0.41).

CONCLUSION

This preliminary work suggests that LCI may be a useful biomarker to measure the effects of e-cigarette use on ventilation distribution and to track early functional impairment of the small airways.

Prenatal ozone exposure and child lung function: Exploring effect modification by oxidative balance score

BACKGROUND

Prenatal exposures to ozone (O3) may impact child lung function, including through oxidative stress pathways, contributing to lifelong morbidity. Diet, reflected in oxidative balance scores (OBS), may modify these pathways and is a potential target for interventions to mitigate O3 effects.

METHODS

We examined associations between prenatal exposure to O3 and child lung function at age 8-9 years via spirometry in the CANDLE cohort within the ECHO-PATHWAYS Consortium. O3 was estimated using a point-based spatiotemporal model and averaged over fetal morphological lung development phases: pseudoglandular, canalicular, and saccular. Lung function z-scores were calculated for FEV1, FVC, FEV1/FVC, and FEF25-75. OBS during pregnancy was derived using maternal diet and lifestyle factors. Linear regression models adjusted for child, maternal, and neighborhood characteristics and exposure in other prenatal windows. Using two and three-way multiplicative interaction terms, we explored effect modification by OBS and maternal race.

RESULTS

Women (N = 661) self-identified as Black (61%), White (33%), or another race (6%); 40.7% attended some college/technical school. Mean O3 concentrations ranged from 26.1 to 29.5 ppb across exposure windows. No associations between prenatal O3 exposure and lung function were observed in primary models, although there was a suggestive adverse association of 10 ppb higher O3 in the saccular window (24-35 weeks) with lower z-scores for FEV1/FVC (-0.23, 95% CI: -0.52, 0.05) and FEF25-75 (-0.17, 95% CI: -0.43, 0.09). No effect modification by OBS or maternal race was found in two-way models. In three-way interaction models, higher O3 was associated with lower child FEV1 among Black women with lower OBS and among White women with higher OBS although data was sparse for those with the highest OBS.

CONCLUSIONS

In a large, well-characterized pregnancy cohort, we did not find robust evidence of an effect of prenatal O3 on lung function. There was suggestion of enhanced vulnerability for some subgroups in exploratory analyses.

Elexacaftor/Tezacaftor/Ivacaftor Treatment Accessibility and Mental Health: Reducing Anxiety in People With Cystic Fibrosis

BACKGROUND

Although modulator therapies have proven effective in cystic fibrosis (CF) access is limited due to reimbursement issues in Turkey. We aimed to examine anxiety and depression levels of people with CF (pwCF) and their caregivers according to their access to modulator treatment.

METHODS

Participants genetically eligible for elexacaftor/tezacaftor/ivacaftor (ETI) were divided into Group 1 (access via court decision, not yet on treatment) and Group 2 (unable to access due to reimbursement issues). Genetically ineligible participants formed Group 3. All pwCF and parents of those under 18 were screened for depression by the Patient Health Questionnaire-9 (PHQ-9) and for anxiety by the Generalized Anxiety Disorder-7 (GAD-7). Surveys for Group 1 patients were conducted just before starting ETI. Binary logistic regression analysis was performed to evaluate the effects of independent variables on anxiety and depression in pwCF and their primary caregivers.

RESULTS

A total of 389 pwCF and 285 caregivers were included. Group 3 (ineligible) had the highest depression rate (72.9%, n = 35), while Group 1 (pre-ETI) had the lowest (50.0%, n = 35). Median PHQ-9 scores were significantly lower in Group 1 (p < 0.006). Anxiety rates were higher in Groups 2 and 3 compared to Group 1 (p = 0.011 and p = 0.003, respectively). Access to ETI reduced the odds of anxiety by 67.7% (p = 0.029). Caregiver GAD-7 scores showed a weak negative correlation with pwCF age (r = -0.117).

CONCLUSION

Limited access to modulator therapies is associated with higher depression and anxiety symptoms among pwCF. Addressing these barriers is critical to improving their well-being.

Examining discordance in spirometry reference equations: A retrospective study

This study aimed to evaluate discordance, binary classification, and model fit between race-predicted and race-neutral spirometry prediction equations. Spirometry data from 9506 patients (18-95 years old) self-identifying as White, Black, or Hispanic were analyzed, focusing on the lower limit of normal (LLN). Best-fit prediction equations were developed from 3771 patients with normal spirometry, using Bayesian Information Criterion (BIC) to compare models with and without race as a covariate. Results showed that including race as a covariate improved model fit, reducing BIC by at least ten units compared to Race-Neutral equations. Discordance between race-specific and race-neutral equations for detecting airway obstruction and restrictive spirometry patterns ranged from 4% to 13%. Using race-neutral equations resulted in false discovery rates (FDR) of 14% for Hispanics and 45% for Blacks and false negative rates (FNR) of 21% for Hispanics and 27% for Blacks in diagnosing airway obstruction. These findings indicate that removing race as a covariate in spirometry equations increases FDR and FNR, leading to higher misclassification rates. The 4%-13% discordance in interpreting airway obstruction and restrictive patterns has significant clinical implications, underscoring the need for careful consideration in developing spirometry reference equations.

Comparison of Race-Neutral versus Race-Specific Spirometry Equations for Evaluation of Child Asthma

Rationale: Race-based estimates of pulmonary function in children could influence the evaluation of asthma in children from racial and ethnic minoritized backgrounds. Objectives: To determine if race-neutral (Global Lung Function Initiative [GLI]-Global) versus race-specific (GLI-Race-Specific) reference equations differentially impact spirometry evaluation of childhood asthma. Methods: The analysis included 8,719 children aged 5 to <12 years from 27 cohorts across the United States grouped by parent-reported race and ethnicity. We analyzed how the equations affected FEV1, FVC, and FEV1/FVC z-scores. We used multivariable logistic models to evaluate associations between z-scores calculated with different equations and asthma diagnosis, emergency department visits, and hospitalization. Measurements and Main Results: For Black children, the GLI-Global versus GLI-Race-Specific equations estimated significantly lower z-scores for FEV1 and FVC but similar values for FEV1/FVC, thus increasing the proportion of children classified with low FEV1 by 14%. Although both equations yielded strong inverse relationships between FEV1 and FEV1/FVC z-scores and asthma outcomes, these relationships varied across racial and ethnic groups (P < 0.05). For any given FEV1 or FEV1/FVC z-score, asthma diagnosis and emergency department visits were higher among Black and Hispanic than among White children (P < 0.05). For FEV1, GLI-Global equations estimated asthma outcomes that were more uniform across racial and ethnic groups. Conclusions: Parent-reported race and ethnicity influenced relationships between lung function and asthma outcomes. Our data show no advantage to race-specific equations for evaluating childhood asthma, and the potential for race-specific equations to obscure lung impairment in disadvantaged children strongly supports using race-neutral equations.

Differences in percentage predicted spirometric values obtained with thirteen reference equations applied to healthy children

BACKGROUND

There is limited information on the discrepancy between the spirometric values calculated with diverse spirometric prediction equations in normal children.

OBJECTIVE

To determine the differences in percentage predicted (PP) values calculated through thirteen prediction equations (PEs) in healthy Chilean children.

METHODS

We compared the PP values for FVC, FEV1, FEF25-75% and FEV1/FVC obtained by applying thirteen PEs, using GLI-2012 as a gold standard reference equation and including race neutral GLI-2022 in the analysis; PP values are from a group of 208 healthy Chilean children aged 7 to 17 years.

RESULTS

In boys, the range of differences for FVC between PEs compared to the reference group went from -5.47% to 20.82% and from -6.4% to 19.74% in girls. For FEV1, in girls, the range of differences went from -5.96% to 18.01% and from -5,04% to 20.67% in boys. Significant differences between GLI-2012 PPs and the other PEs were observed more frequently in girls than in boys (p < 0.001).

CONCLUSIONS

There is a wide difference between the spirometric PPs values by different PEs, including race neutral GLI-2022. Our findings, especially given the potential interpretative and clinical implications, might suggest the need for conducting standardized, multicenter studies in Latin America to determine which PEs would better fit pediatric populations in this region.

Exposure to urinary polycyclic aromatic hydrocarbon metabolites for the effect of lung function among children and adolescents: Epidemiological study and mechanism exploration

Human are widely exposed to polycyclic aromatic hydrocarbon (PAHs), but existing evidence about exposure to urinary PAHs metabolites for pulmonary health in children and adolescents is limited. Our aim was to examine the effect of single and mixed exposure of urinary PAHs metabolites on lung function among children and adolescents. We included 1417 individuals aged 6-19 years from 3 survey cycles (2007-2008, 2009-2010, 2011-2012) of NHANES program. Multivariable linear regression model was conducted to examine the relationship between urinary PAHs metabolites and lung function index including FEV1, FVC and FEV1/FVC. BKMR and WQS model were used to evaluate the joint effects of PAHs metabolites for lung function index. Mediation analyses were performed to investigate the mediating role of inflammation related index. Hub proteins were screened by network toxicology and validated using molecular docking. Our results indicated that 3-FLU was negatively linked with FEV1 and FEV1/FVC; 1-OHP was negatively linked with FEV1; 1-PYR was negatively linked with FEV1 and FVC. In addition, 3-OHP was positively corrected with three lung function parameters. In BKMR and WQS models, PAHs metabolites co-exposure was all negatively corrected with FEV1 and FVC. Systemic inflammation response index mediated the relationship between I-PYR and FEV1 as well as FVC, with the 8 % and 6 % proportion. IL-6, STAT3, TNF, and TP53 were screened and validated as the common targets related with PAHs, inflammation and lung function by molecular docking analysis. Taken together, our findings raise the concerns about the potential hazards of environmentally relevant PAHs metabolites exposure for respiratory system in the vulnerable population and guide future research into the toxic mechanisms of PAHs metabolites-mediated lung function injury, which has important public health implications.

Dupilumab Efficacy and Safety in Children With Moderate to Severe Asthma and High Blood Eosinophils: A Post Hoc Analysis of VOYAGE

BACKGROUND

Elevated blood or tissue eosinophils are considered to characterize type 2 inflammation in children with asthma and are associated with increased exacerbation rates and worse asthma control. Dupilumab, a human mAb that blocks type 2 inflammatory drivers IL-4 and IL-13, reduced severe exacerbation rates and improved lung function versus placebo in children aged 6 to 11 years with uncontrolled moderate to severe asthma in the phase 3 LIBERTY ASTHMA VOYAGE study (NCT02948959).

OBJECTIVE

To assess dupilumab efficacy and safety in children from VOYAGE with moderate to severe asthma and greater than or equal to 500 and less than 1500 blood eosinophils/μL at baseline.

METHODS

Children received add-on dupilumab (100/200 mg by body weight) or matched placebo every 2 weeks for 52 weeks. We assessed annualized severe exacerbation rates, least squares mean change from baseline in prebronchodilator percent predicted FEV1, and incidence of treatment-emergent adverse events.

RESULTS

In children with elevated baseline eosinophils (N = 174), dupilumab versus placebo significantly reduced annualized exacerbation rates by 67% (95% CI, 38%-82%; P < .001) and improved prebronchodilator percent predicted FEV1 from baseline at weeks 24 and 52 (week 24 least squares mean difference, 7.58 percentage points; 95% CI, 2.85-12.31; P = .002; week 52 least squares mean difference, 7.98 percentage points; 95% CI, 2.17-13.78; P = .007). The incidence of treatment-emergent adverse events was similar with dupilumab and placebo.

CONCLUSIONS

Dupilumab significantly reduced severe exacerbations and improved lung function in children with moderate to severe asthma and baseline blood eosinophil counts greater than or equal to 500 and less than 1500 cells/μL, with a safety profile comparable with the overall study population.

Changes in peak oxygen consumption in Fabry disease and associations with cardiomyopathy severity

BACKGROUND

Fabry disease (FD) causes multiorgan sphingolipid accumulation, with cardiac involvement responsible for the largest burden of morbidity and mortality. Exercise intolerance in FD is prevalent, yet the mechanisms of this are poorly understood. The aim of this study was to assess exercise intolerance in FD and identify whether this correlates with the phase of cardiomyopathy.

METHODS

This was a retrospective observational study of adults with FD undergoing cardiopulmonary exercise testing (CPEX) between September 2011 and September 2023 at a national referral centre in the UK. The primary outcome measure was peak oxygen uptake (V̇O2peak), with forced expiratory volume in 1 s (FEV1) used to quantify respiratory impairment. Age-normalised/sex-normalised values were additionally calculated, based on published normal ranges for subgroups of age and sex. The cardiomyopathy phase was classified on a 4-point scale by two FD experts using contemporaneous imaging and biochemistry results.

RESULTS

CPEX was completed by 42 patients, with a median age of 54 years and of whom 62% were male. Patients were approximately equally distributed across the four cardiomyopathy phases. At phase I, the mean (±SD) V̇O2peak was 28.7±7.7 mL/kg/min, which represented a significant underperformance of 23%, relative to age-normalised and sex-normalised values (expected mean: 37.3±3.2 mL/kg/min, p=0.006). V̇O2peak declined significantly across the cardiomyopathy phases (p=0.010), reaching a mean of 21.2±6.1 mL/kg/min at phase IV. Normalised FEV1 was not found to show a corresponding significant change with cardiomyopathy phase (p=0.683). Impaired left atrial global longitudinal strain as well as biochemical markers of inflammation were associated with impaired V̇O2peak.

CONCLUSIONS

This study identifies significantly impaired aerobic capacity in FD, even in those without phenotypic cardiomyopathy. No corresponding changes in respiratory impairment were observed, suggesting that exercise intolerance may be due to early cardiac sphingolipid accumulation and subsequent atrial and ventricular dysfunction, which increases as cardiomyopathy progresses. As such, peak V̇O2peak holds promise as a therapeutic marker of response to FD-specific therapy.

Within- and between-day test-retest reliability of responses to rapid bilateral anterolateral magnetic phrenic nerve stimulation in healthy humans (ReStim)

Background

Mechanical ventilation can lead to lung injury and diaphragmatic dysfunction. Rapid bilateral anterolateral magnetic phrenic nerve stimulation (rBAMPS) may attenuate both of the aforementioned issues by inducing diaphragm activation. However, in order for rBAMPS to become part of standard of care, the reliability of inspiratory responses to rBAMPS needs to be established.

Methods

Eighteen healthy participants (9F) underwent five blocks of 1-s rBAMPS at 25 Hz starting at 20% of maximal stimulator output with 10% increments. Three blocks were completed on the same day to test within-day reliability, and two additional blocks were each completed on subsequent days to test between-day reliability. Mean transdiaphragmatic pressure (Pdi,mean), tidal volume (VT), discomfort, pain, and paresthesia were recorded for each rBAMPS. Relative and absolute reliability of both Pdi,mean and VT were quantified by calculating intraclass correlation coefficients (ICC) and standard error of measurements (SEM), respectively. An ordinal regression was used to determine changes of sensory ratings within and between days.

Results

At all stimulator outputs, within-day Pdi,mean displayed "good" reliability (ICC range 0.78-0.89). Between days, Pdi,mean reliability was also "good" (ICC range 0.79-0.87) at stimulator outputs of 20%-50% of maximum, but "moderate" (ICC range 0.56-0.72) at stimulator outputs of 60%-100%. SEM for Pdi,mean within day ranged from 0.9 to 3.4 across tested stimulator outputs and increased on average by 1.4 ± 0.9 between days. The VT reliability was "good" to "excellent" within (ICC range 0.82-0.94) and between (ICC range 0.81-0.96) days at all stimulator outputs. SEM for VT within day ranged from 0.08 to 0.36 and from 0.11 to 0.30 between days and tended to be larger at stimulator outputs greater than 50% of maximum. Subsequent blocks within day were associated with decreased discomfort and pain (P ≤ 0.043), while subsequent days were associated with decreased discomfort and paresthesia (P < 0.001).

Discussion

rBAMPS appears to induce reliable diaphragmatic contractions, while select sensory responses become blunted over repeated stimulations. However, as reliability is slightly lower between days compared to within day, stimulation parameters may need to be adjusted to achieve similar responses on different days.

Risk of All-Cause Mortality in US Adults With Preserved Ratio Impaired Spirometry: An Observational Study

Background

Preserved ratio impaired spirometry (PRISm) is defined as forced expiratory volume in one second (FEV1)/forced vital capacity (FVC)≥0.70 and FEV1<80% predicted. Previous studies have shown that individuals with PRISm may develop airflow obstruction and have an increased mortality risk. However, studies with long-term follow-up are lacking, and this topic has not been evaluated in the general population. We explored the all-cause mortality risk of individuals with PRISm in a large sample of the general population.

Methods

We used data from the National Health and Nutrition Examination Survey III and 2007-2012. Participants aged 20-79 years at baseline and who underwent spirometry were included. Normal spirometry was defined as a prebronchodilator FEV1/FVC≥0.70 and FEV1≥80% predicted. We used Cox proportional hazards regression models to compare all-cause mortality between the groups. We performed sensitivity analyses stratified by the lower limit of normal definition of spirometry criteria. Subgroup analyses by sex, age, smoking status, race, body mass index, level of education, poverty-to-income ratio, respiratory symptoms, and comorbidities were performed in participants with the different spirometry classifications.

Results

Overall, 24,691 participants were included, with a median follow-up time of 25.7 years. Of these, 19,969 had normal spirometry and 1,452 had PRISm. PRISm was associated with a high all-cause mortality risk (unadjusted hazard ratio [HR]=2.47, 95% confidence interval [CI]: 2.25-2.71, P<0.001; adjusted HR=1.69, 95% CI: 1.54-1.86, P<0.001) compared with normal spirometry. Sensitivity analyses and subgroup analyses showed a similar increased all-cause mortality risk in PRISm.

Conclusion

Our finding revealed that PRISm was significantly associated with increased risk of all-cause mortality in the general population compared with normal spirometry. Further research is needed to explore the intervention effect of PRISm.

Race-Specific and Race-Neutral Equations for Lung Function and Asthma Diagnosis in Black Children

Importance

Use of the race-neutral Global Lung Initiative (GLI) equation has been shown to generate decreased lung function measures in Black children and adults. The effect on asthma detection and diagnosis in children is unknown.

Objective

To compare the use of race-specific vs race-neutral equations on subsequent asthma diagnosis in children.

Design, Setting, and Participants

The Childhood Asthma Management Program (CAMP, 1991-2012), the Cincinnati Childhood Allergy and Air Pollution Study (CCAAPS, 2001-2010), and the Mechanisms of Progression from Atopic Dermatitis to Asthma (MPAACH, 2016-2024) cohorts were included in this cohort study. Children in the CAMP cohort were aged 5 to 12 years with mild to moderate asthma. The CCAAPS and MPAACH cohorts included infants from atopic parents and children aged 0 to 2 years with atopic dermatitis, respectively. Data were analyzed from November 2023 to May 2024.

Exposures

Race-specific vs race-neutral GLI equations to define lung function.

Main Outcomes and Measures

Percent predicted values of forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), asthma or asthma symptoms, and eligibility for reversibility testing were determined.

Results

Among 1533 children, there were 849 CAMP (median [IQR] age, 8.7 [7.1-10.6] years; 138 [16%] Black, 711 [84%] White, and 498 [59%] male participants), 578 CCAAPS (median [IQR] age, 6.9 [6.7-7.0]; 115 [20%] Black, 463 [80%] White, and 315 [55%] male participants) and 106 MPAACH (median [IQR] age, 7.4 [7.1-7.8] years; 62 [58%] Black, 44 [42%] White, and 62 [58%] male participants). The median (IQR) percent predicted FEV1 in Black children decreased by 11.9 percentage points (pp) (10.4-13.1 pp) in CAMP, 13.5% pp (11.8-14.6 pp) in CCAAPS, and 13.2 pp (11.6-14.6 pp) in MPAACH compared with the race-specific equation. The race-specific equation failed to detect reduced percent predicted FEV1 in 12 of 22 Black children in CCAAPS with asthma symptoms (55%) and 5 of 15 Black children in MPAACH with asthma (41%). In CCAAPS, children with less than 90% predicted FEV1 based on race-specific equations were eligible for postreversibility testing to objectively diagnose asthma. When this asthma diagnostic algorithm was applied, 16 of 36 Black children in CCAAPS (44%) and 6 of 16 Black children in MPAACH (38%) who were not eligible for reversibility testing based on the race-specific equation became eligible with a less than 90% predicted FEV1 based on the race-neutral equation.

Conclusions and Relevance

In this cohort study of 1533 children, the use of the race-neutral equation improved the detection of asthma in children. These results support the universal use of the race-neutral equation to improve asthma detection in children and help guide medical practice toward alleviating asthma-related health disparities.

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.

Implications of Global Lung Function Initiative Spirometry Reference Equations in Northeast Asian Patients With COPD

BACKGROUND

Accurate spirometry interpretation is critical in the diagnosis and management of COPD. With increasing efforts for a unified approach by the Global Lung Function Initiative (GLI), this study evaluated the application of race-specific 2012 GLI and race-neutral 2022 GLI reference equations compared with Choi's reference equations, which are derived and widely used in South Korea, for spirometry interpretation in Northeast Asian patients with COPD.

RESEARCH QUESTION

What are the effects of applying race-specific 2012 GLI, race-neutral 2022 GLI, and Choi's reference equations on the diagnosis, severity grade, and clinical outcome associations of COPD?

STUDY DESIGN AND METHODS

Serial spirometry data from the Korea COPD Subgroup Study (KOCOSS) consisting of 3,477 patients were used for reanalysis using 2012 GLI, 2022 GLI, and Choi's reference equations. The COPD diagnosis and severity categorization, associations with disease manifestations and health outcomes, and longitudinal trajectories of lung function were determined.

RESULTS

Although there was strong concordance in COPD diagnosis comparing 2012 GLI, and 2022 GLI reference equations with Choi's reference equations, a notable portion of patients were reclassified to milder disease severity (17.0% and 23.4% for 2012 GLI and 2022 GLI reference equations, respectively). Relationships between FEV1 % predicted values calculated using 2012 GLI, 2022 GLI, and Choi's equations with clinical outcomes including dyspnea severity, exercise capacity, health-related quality of life, and frequency of exacerbations remain consistently significant. Similar annual decline rates of FEV1 and FVC % predicted were observed among the reference equations used, except for slower annual decline rate of FEV1 in Choi's equation compared with 2022 GLI race-neutral equation.

INTERPRETATION

Application of GLI reference equations for spirometry interpretation in Northeast Asian patients with COPD has potential implications on disease severity grade for clinical management and trial participation, and maintains consistent significant relationships with key disease outcomes.

Oscillometry in the diagnosis, assessment, and monitoring of asthma in children and adults

Diagnosing asthma typically relies on clinical history, physical examination, and objective lung function test results. Spirometry, the gold standard for assessing lung function, is universally recommended for the diagnostic, assessment, and monitoring of asthma. It requires maximal respiratory effort that limits cooperation in certain populations and has limitations in detecting small airway dysfunction. Oscillometry requires minimal patient effort, is noninvasive, and provides valuable information on both large and small airways. Recent task force reports have suggested oscillometry as an alternative or a complementary lung function test to spirometry in the management of individuals with asthma. This review explores the scientific evidence and psychometric properties regarding oscillometry in the main purposes served by lung function testing in asthma, namely diagnosis, assessment of control and future risk, as well as longitudinal monitoring, including clinical utility. Furthermore, it addressed challenges and facilitators to implementation and future directions regarding its positioning as lung function testing in individuals with asthma.

Associations between ultra-processed foods intake and preserved ratio impaired spirometry in U.S. adults

Background

Preserved Ratio Impaired Spirometry (PRISm) is increasingly recognized as a precursor to Chronic Obstructive Pulmonary Disease (COPD). The impact of Ultra-Processed Foods (UPFs) intake on PRISm and lung function remains underexplored, and we aimed to explore their associations.

Methods

This study included 8,336 U.S. adults. Weighted logistic and linear regression models were employed for main analysis. Dose-response relationship was examined through restricted cubic spline (RCS) analysis, and subgroup analyses explored interactions with selected covariates.

Results

Participants in the PRISm group were older and exhibited various adverse health characteristics. The percentage of total daily energy intake from UPFs (%Kcal) intake was associated with a non-significant increase in PRISm risk (OR 1.67, 95% CI: 0.96-2.92, p = 0.07). However, the highest quartile of UPFs (%Kcal) intake was significantly linked to increased PRISm risk (OR 1.36, 95% CI: 0.99-1.86, P for trend = 0.043). Furthermore, higher UPFs (%Kcal) intake negatively affected lung function, with participants in the highest quartile showing a significant reduction in forced expiratory volume in 1 s (FEV1) of -45.5 mL (95% CI: -87.6 to -3.4, P for trend = 0.045) and a decrease in forced vital capacity (FVC) of -139.4 mL (95% CI: -223.5 to -55.4, p < 0.001) compared to those in the lowest quartile. RCS analysis demonstrated linear relationships for both PRISm and lung function. Subgroup analysis revealed increased susceptibility primarily among individuals with occupational exposure. Additionally, sensitivity analysis indicated that a higher percentage of total daily intake from UPFs (%Grams) intake was significantly associated with an increased risk of PRISm (OR 1.86, 95% CI: 1.07-3.25, p = 0.03).

Conclusion

Higher intake of UPFs is linked to an increased risk of PRISm and negatively affects lung function, particularly in individuals with occupational exposure.

Development and External Validation of a Machine Learning Model to Predict Restriction from Spirometry

Background

Though European Respiratory Society and American Thoracic Society (ERS/ATS) guidelines for pulmonary function test (PFT) interpretation recommend the use of the forced vital capacity (FVC) lower limit of normal (LLN) to exclude restriction, recent data suggest that the negative predictive value (NPV) of the FVC LLN is lower than has been accepted, particularly among non-Hispanic Black patients. We sought to develop and externally validate a machine learning (ML) model to predict restriction from spirometry and determine whether its use may improve the accuracy and equity of PFT interpretation.

Methods

We included PFTs with both static and dynamic lung volume measurements for patients between 18 and 80 years of age who were tested at pulmonary diagnostic labs within two health systems. We used PFTs from one health system to train logistic regression, random forest, and boosted tree models to predict restriction using demographic, anthropometric, and spirometric data. We used PFTs from the second health system to externally validate these models. The primary measure of model performance was the NPV. Racial equity was assessed by comparing the NPV among non-Hispanic Black and non-Hispanic White patients.

Findings

A total of 42 462 PFTs were used for model development and 24 524 for external validation. The prevalence of restriction was 29.8% in the development dataset and 39.6% in the validation dataset. All three ML models outperformed the FVC LLN by a wide margin, both overall and among all demographic subgroups. The overall NPV of the random forest model (88.3%, 95% confidence interval [CI] 87.8% to 88.9%) was significantly greater than that of the FVC LLN (72.7%, 95% CI 72.1% to 73.3%). The NPV of the random forest model was greater than that of the FVC LLN among both non-Hispanic Black (74.6% [95% CI 72.5% to 76.6%] versus 49.5% [95% CI 47.8% to 51.2%]) and non-Hispanic White (90.9% [95% CI 90.3% to 91.5%] versus 79.6% [95% CI 78.9% to 80.3%]) patients.

Interpretation

ML models to exclude restriction from spirometry improve the accuracy and equity of PFT interpretation but do not fully eliminate racial differences.

Debunking the GAMLSS myth: Simplicity reigns in pulmonary function diagnostics

RATIONALE

Current technical standards advocate using Generalized, Additive Models of Location, Scale, and Shape (GAMLSS) for lung function reference equations. These equations are complicated and require supplementary spline tables.

OBJECTIVE

(1) To demonstrate that segmented (piecewise) linear regression (SLR) yields prediction accuracies similar to GAMLSS in pulmonary function diagnostics. (2) To determine the agreement between both SLR and GAMLSS.

METHODS

The NHANES 2007-2012 database was utilized to construct spirometric reference equations for FEV1, FVC, and FEV1/FVC using both SLR and GAMLSS modeling techniques. K-fold cross-validation was used to provide the 95% confidence interval (CI) of the root-mean-square error (RMSE) as an indicator of prediction accuracy. Additionally, agreement was assessed between the two modeling techniques in classifying spirometric patterns (standard, airflow obstruction, restrictive, or mixed disorder) using an unweighted kappa statistic.

RESULTS

The RMSE values for FEV1, FVC, and FEV1/FVC and correlation coefficients between predicted values and test data were similar between the two techniques. Agreement in classifying spirometric patterns between the two techniques ranged from 0.78 to 0.80 (95 % CI).

CONCLUSIONS

The findings suggest that simple linear regression for FEV1/FVC and SLR for FEV1 and FVC offer prediction accuracies on par with GAMLSS while being more straightforward, parsimonious, and accessible to a broader audience in the field of pulmonary function diagnostics.

Aging with CF: Characteristics of people with CF aged 40 and older in the United States

We conducted a descriptive analysis of people with CF 40 years of age and older using CF Foundation Patient Registry data from 2022 to provide a current estimate of the population size and characteristics. We summarized demographic details including biological sex, race, ethnicity, insurance and employment status. Clinical data including body mass index, lung function, respiratory infections, hospitalization rates, prevalence of CF-related complications and CF therapy prescriptions were collated. A total of 5,243 individuals aged 40 years or older contributed data to the CFFPR: 2,687 (51 %) people aged 40-49 years; 1,410 (27 %) people aged 50-59 years; and 1,146 (22 %) people aged 60 years or older. The ≥60 year old group have unique characteristics compared to younger individuals, with later diagnosis of CF and greater proportion of females (58 %). These results highlight heterogeneity in the older CF adult population and the need to develop and individualize CF care practices.

Dendriform pulmonary ossification in military combat veterans: A case series

Dendriform pulmonary ossification (DPO) is a rare condition characterized by mature bone formation in the lung. DPO has been linked to various conditions, but little is known about the link between DPO and hazardous airborne exposures. We queried research databases of military personnel evaluated for deployment-related respiratory diseases at two occupational pulmonary medicine clinics (Colorado, USA) for diagnoses of DPO, and summarized demographics, Gulf War military deployment history, medical history, and pulmonary function testing. Chest imaging was independently reviewed and scored by a thoracic radiologist, and all cases had undergone lung tissue biopsy. We identified five male combat veterans with DPO, median age 49 years [range: 32-64]. All had deployed to Southwest Asia or Afghanistan during the First or Second Gulf War, and all reported frequent, intense exposure to diesel exhaust, burn pit emissions, and sandstorms. Lung physiology was abnormal in all cases. The most prevalent chest imaging and histopathology findings were airway-centric injury, inflammation, and retained particulate matter, suggesting substantial hazardous exposure during military deployment. This case series of a rare lung disease from the only two contemporary Colorado clinics serving previously deployed veterans highlights a potential link between airborne hazards and lung injury leading to DPO. A high index of clinical suspicion combined with a detailed occupational history may reveal additional exposure-related associations with DPO. Access to large medical databases of military veterans with linkage to exposure histories may further elucidate risk factors for lung injury with ossification, paving the way for targeted prevention.

The discrepant effect of blood glucose on the risk of early and late lung injury: a national cohort study

BACKGROUND

The association between glycemic control and short-, and long-term lung health remains controversial. This study aimed to investigate the relationship between glucose control and overall lung health in a national cohort.

METHODS

The analysis included 5610 subjects from NHANES 2007-2012. We assessed the correlation of glycemic status with respiratory symptoms (cough, sputum, wheeze, and exertional dyspnea), lung function (forced expiratory volume in 1-s (FEV1), forced vital capacity (FVC)), and obstructive or restrictive lung disease (RLD). Furthermore, we determined all-cause mortality in patients with restrictive lung disease by linking data to the National Mortality Index records up to December 31, 2019.

RESULTS

The study involved the examination of respiratory symptoms, pulmonary function tests, and mortality analyses encompassing 3714, 3916, and 173 subjects, respectively. Multifactorial regression analyses revealed that a 1% increase in blood glucose was associated with a reduction in effect sizes (β) for FVC and FEV1 by -1.66% (-2.47%, -0.86%) and -1.94% (-2.65%, -1.23%), respectively. This increase also exhibited correlations with an elevated risk of exertional dyspnoea, restrictive ventilation dysfunction, and all-cause mortality, presenting odds ratios (ORs) of 1.19 (1.06, 1.33), 1.22 (1.10, 1.36), and 1.61 (1.29, 2.01), respectively. Regarding glycemic control, patients with improved control demonstrated stronger associations with early lung damage, significantly correlating with reduced FVC (β -10.90%, [-14.45%, -7.36%]) and FEV1 (β -9.38%, [-12.90%, -5.87%]). Moreover, they experienced a notably higher risk of exertional dyspnoea (adjusted OR 2.09, [1.35- 3.24]), while the diabetic group with poorer glycemic control showed more significant connections with advanced lung damage. This group exhibited significant associations with an increased risk of restrictive ventilatory dysfunction (adjusted OR, 2.56, [1.70-3.86]) and all-cause mortality (hazard ratios [HRs] 2.65, [1.05-6.67]), all compared to the reference group with normal glycemic metabolism.

CONCLUSIONS

Elevated blood glucose exhibited an inverse correlation with both long-term and short-term lung health. A negative L-shaped relationship was observed between glycemic control and early lung injury, along with a linearly negative association concerning late-stage lung damage. Given the cross-sectional nature of this study, a longitudinal investigation is needed to validate our findings.

Development, Progression, and Mortality of Suspected Interstitial Lung Disease in COPDGene

Rationale: Some with interstitial lung abnormalities (ILA) are suspected to have interstitial lung disease (ILD), a subgroup with adverse outcomes. Rates of development and progression of suspected ILD and their effect on mortality are unknown. Objectives: To determine rates of development, progression, and mortality in those with suspected ILD and assess effects of individual ILD and progression criteria. Methods: Participants from COPDGene (Genetic Epidemiology of Chronic Obstructive Pulmonary Disease) with ILA characterization and FVC at enrollment and 5-year follow-up were included. ILD was defined as ILA and fibrosis and/or FVC < 80% predicted. Prevalent ILD was assessed at enrollment and incident ILD and progression were assessed at 5-year follow-up. Computed tomography (CT) progression was assessed visually and FVC decline as relative change. Multivariable Cox regression tested associations between mortality and prevalent ILD, incident ILD, and progression groups. Measurements and Main Results: Of 9,588 participants at enrollment, 268 (2.8%; 51% of ILA) had prevalent ILD. Those with prevalent ILD had 51% mortality after median 10.6 years, which was higher than those with ILA without prevalent ILD (henceforth ILA) (33%; hazard ratio [HR], 2.0; P < 0.001). The subgroup of prevalent ILD with only fibrosis criteria (FVC ≥ 80%) had worse mortality (58%) than ILA (HR, 2.2; P < 0.001). A total of 98 participants with prevalent ILD completed 5-year follow-up: 33% had stable CT and relative FVC decline <10%, 6% had FVC decline ≥10% only, 39% had CT progression only, and 22% had both CT progression and FVC decline ≥10%. Mortality rates were 31%, 50%, 45%, and 45%, respectively; those with only CT progression had worse mortality than those with ILA (HR, 2.6; P = 0.005). At 5-year follow-up, incident ILD occurred in 148/4,842 participants without prevalent ILD (5.5/1,000 person-years) and had worse mortality than ILA (HR, 2.4; P < 0.001). Conclusion: Rates of mortality and progression are high among those with suspected ILD in COPDGene; fibrosis and radiologic progression are important predictors of mortality.

Is it time to end race and ethnicity adjustment for pediatric pulmonary function tests?

The continued inclusion of race in spirometry reference equations is a topic of intense debate for adult lung function, but less discussion has focused on implications for children. Obtaining accurate estimates of children's lung function is an important component of the diagnosis of childhood respiratory illnesses, including asthma, cystic fibrosis, and interstitial lung disease. Given the higher burden among racial/ethnic minorities for many respiratory illnesses, it is critical to avoid racial bias in interpreting lung function. We recommend against the continued use of race-specific reference equations for a number of reasons. The original reference populations used to develop the equations were comprised of children with restricted racial diversity, relatively small sample sizes, and likely included some unhealthy children. Moreover, there is no scientific justification for innate racial differences in lung function, as there is no clear physiological or genetic explanation for the disparities. Alternatively, many environmental factors harm lung development, including allergens from pests, asbestos, lead, prenatal smoking, and air pollution, as well as preterm birth and childhood respiratory illnesses, which are all more common among minority racial groups. Race-neutral equations may provide a temporary solution, but still rely on the racial diversity of the reference populations used to build them. Ultimately researchers must uncover the underlying factors truly driving racial differences in lung function.

A refined spirometry dataset for comparing segmented (piecewise) linear models to that of GAMLSS

Generalized Additive Models for Location, Scale, and Shape (GAMLSS) are widely used for developing spirometric reference equations but are often complex, requiring additional spline tables. This study explores the potential of Segmented (piecewise) Linear Regression as an alternative, comparing its predictive accuracy to GAMLSS and examining the agreement between the two methods. Spirometry data from nearly 16,600 patients, deemed Grade "A" and "B" acceptable from the NHANES 2007-2012 dataset, was analyzed. The dataset includes both nominal and scalar variables. Reference equations for forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), and the ratio (FEV1/FVC) were generated using GAMLSS (FEV1, FVC, FEV1/FVC), Segmented Linear Regression (FEV1, FVC) and multiple linear regression (FEV1/FVC). K-fold cross-validation was employed to compare prediction accuracy, using root-mean-square error (RMSE) and correlation coefficients. Agreement in classifying spirometric patterns (i.e. airway obstruction, restrictive spirometry pattern, mixed obstructive and restrictive disorder) was evaluated with the kappa statistic. This study uniquely compares the models by incorporating the lower limit of normal (LLN) using fitted z-scores of -1.645 or -1.96. The dataset is publicly available in SPSS (.sav) and .csv formats through the Mendeley Data repository.

Mexican Hispanics show significant improvement in lung function approximately 1 year after having severe COVID-19

The long-term effects of COVID-19 on lung function are not understood, especially for periods extending beyond 1 year after infection. This observational, longitudinal study investigated lung function in Mexican Hispanics who experienced severe COVID-19, focusing on how the length of recovery affects lung function improvements. At a specialized COVID-19 follow-up clinic in Yucatan, Mexico, lung function and symptoms were assessed in patients who had recovered from severe COVID-19. We used z-scores, and Wilcoxon's signed rank test to analyse changes in lung function over time. Lung function was measured twice in 82 patients: the first and second measurements were taken a median of 94 and 362 days after COVID-19 diagnosis, respectively. Initially, 61% of patients exhibited at least one of several pulmonary function abnormalities (lower limit of normal = -1.645), which decreased to 22% of patients by 390 days post-recovery. Considering day-to-day variability in lung function, 68% of patients showed improvement by the final visit, while 30% had unchanged lung function from the initial assessment. Computed tomography (CT) scans revealed ground-glass opacities in 33% of patients. One year after infection, diffusing capacity of the lungs for carbon monoxide z-scores accounted for 30% of the variation in CT fibrosis scores. There was no significant correlation between the length of recovery and improvement in lung function based on z-scores. In conclusion, 22% of patients who recovered from severe COVID-19 continued to show at least one lung function abnormality 1 year after recovery, indicating a prolonged impact of COVID-19 on lung health.

[Recommendations on interpretive strategies for routine lung function tests]

During the annual conference of the German Respiratory Society (DGP = Deutsche Gesellschaft für Pneumologie und Beatmungsmedizin) in 2024, updated recommendations for lung function testing have been published. The original full-length version can be downloaded free of charge as pfd-paper from the journal entitled "Atemwegs- und Lungenkrankheiten, Jahrgang 50 (2024) März (111-184)". In the current recommendations new approaches have been embedded that focus on modern interpretations of lung function results, as has been proposed by the ERS (European Respiratory Society) in collaboration with the ATS (American Thoracic Society). This targets the spirometry, the whole bodyplethysmography, diffusion capacity testing, testing for bronchodilation, unspecific bronchoprovocation in addition to the reference values. Oscillometry and respiratory muscle function testing are also included in the recommendations. The current publication considers itself as a short version of the most important topics of the full-length lung function recommendations. However, reading also the full-length paper is strongly emphasised based on the understanding that lung function testing is highly important in daily clinical practice when dealing with patients suffering from respiratory diseases.

Application of the European Respiratory Society/American Thoracic Society Spirometry Standards and Race-Neutral Equations in the COPDGene Study

Rationale: For spirometry interpretation, the European Respiratory Society (ERS) and American Thoracic Society (ATS) recommend using z-scores, and the ATS has recommended using Global Lung Initiative (GLI) "Global" race-neutral reference equations. However, these recommendations have been variably implemented, and the impact has not been widely assessed in clinical or research settings. Objectives: To evaluate the ERS/ATS classification of airflow obstruction severity. Methods: In COPDGene (Genetic Epidemiology of COPD Study) (N = 10,108), airflow obstruction has been defined by an FEV1/FVC ratio <0.70, with spirometric severity graded from class 1 to class 4 based on race-specific percent predicted (pp) FEV1 cutoff points as recommended by the Global Initiative for Chronic Obstructive Lung Disease (GOLD). We compared the GOLD approach, using National Health and Nutrition Examination Survey III race-specific equations, versus the application of GLI Global equations using the ERS/ATS definition of airflow obstruction as an FEV1/FVC ratio below the lower limit of normal and z-score-based FEV1 cutoff points of -1.645, -2.5, and -4 ("zGLI Global"). We tested the four-tier severity scheme for association with chronic obstructive pulmonary disease outcomes. Measurements and Main Results: The lowest agreement between ERS/ATS with zGLI Global and the GOLD classification was observed in individuals with milder disease (56.9% and 42.5% in GOLD stages 1 and 2, respectively), and race was a major determinant of redistribution. After adjustment for relevant covariates, zGLI Global distinguished all-cause mortality risk between normal spirometry and the first grade of chronic obstructive pulmonary disease (hazard ratio, 1.23; 95% confidence interval, 1.04-1.44; P = 0.014) and showed a linear increase in exacerbation rates with increasing disease severity in comparison with GOLD. Conclusions: The zGLI Global severity classification outperformed the GOLD criteria in the discrimination of survival, exacerbations, and imaging characteristics.

Severity of Airflow Obstruction Based on FEV1/FVC Versus FEV1 Percent Predicted in the General U.S. Population

Rationale: According to the Global Initiative for Obstructive Lung Disease (GOLD), the FEV1/FVC ratio is used to confirm the presence of airflow obstruction in the diagnosis of chronic obstructive pulmonary disease (COPD), whereas FEV1 percent predicted normal value (FEV1%pred) is used for grading its severity. The STaging of Airflow obstruction by the FEV1/FVC Ratio (STAR), and its prediction of adverse outcomes, has not been evaluated in general populations. Objectives: To compare the STAR (FEV1/FVC) and the GOLD (FEV1%pred) classifications for the severity of airflow limitation in terms of exertional breathlessness and mortality in the general U.S. population. Methods: Severity stages according to the STAR and GOLD were applied to the multiethnic National Health and Nutrition Examination Survey of 2007-2012, including people ages 18-80 years, using a postbronchodilatory FEV1/FVC ratio of <0.70 to define airflow obstruction in both staging systems. Prevalence of the severity stages STAR 1-4 and GOLD 1-4 was calculated, and associations with breathlessness and mortality were analyzed by multinomial logistic regression and Cox regression, respectively. Measurements and Main Results: STAR versus GOLD severity staging of airflow obstruction showed similar associations with breathlessness and all-cause mortality, regardless of ethnicity and/or race. In those with airflow obstruction, the correlation between the two classification systems was 0.461 (P < 0.001). STAR reclassified 59% of GOLD 2 subjects as having mild airflow obstruction (STAR 1). Compared with GOLD 1, STAR 1 was more clearly differentiated from nonobstruction in terms of both breathlessness and mortality. Conclusions: FEV1/FVC and FEV1%pred as measures of airflow limitation severity show similar predictions of breathlessness and mortality in the adult U.S. population across ethnicity groups. However, Stage 1 differed more clearly from nonobstruction on the basis of FEV1/FVC ratio than FEV1%pred.

Changes in spirometry and pulmonary diffusing capacity in Mexican Hispanics approximately one year after having severe COVID-19: A dataset

This observational longitudinal study was conducted at the Long-term follow-up COVID-19 Clinic in Mérida, Mexico, from March to August 2021. A total of 100 patients hospitalized for severe COVID-19 were enrolled. Inclusion criteria required participants to be adults over 18, recovering from severe COVID-19 as defined by the World Health Organization (oxygen saturation below 90 %, severe pneumonia, or signs of severe respiratory distress). Exclusion criteria included pneumonia from non-SARS-CoV-2 causes, mild or moderate COVID-19, or a single follow-up evaluation. Pulmonary function tests were conducted at approximately 100 and 400 days after diagnosis. The dataset includes 82 patients with baseline and follow-up spirometry, pulmonary diffusing capacity and alveolar volume. Morbidity history and fibrosis scores from high-resolution CT scans were also obtained. Finally, fitted z-scores for spirometry and pulmonary diffusing capacity were acquired from established reference equations. The freely accessible data (Version 4) is provided in both SPSS (.sav) and .csv format. at the Mendeley Data cloud-based repository and includes nominal data, ordinal data, and scalar data.

Prenatal exposure to ambient fine particulate matter and child lung function in the CANDLE cohort

BACKGROUND

Ambient fine particulate matter (PM2.5) exposure adversely impacts child airway health; however, research on prenatal PM2.5 exposure, and child lung function is limited. We investigated these associations in the ECHO-PATHWAYS Consortium, focusing on the role of exposure timing during different phases of fetal lung development.

METHODS

We included 675 children in the CANDLE cohort born between 2007 and 2011 in Memphis, TN, USA. Prenatal exposure to ambient PM2.5 was estimated using a spatiotemporal model based on maternal residential history and averaged over established prenatal periods of lung development. Forced expiratory volume in the first second (FEV1) and forced vital capacity (FVC) were measured by spirometry at age 8-9 years. We used linear regression and Bayesian Distributed Lag Interaction Models (BDLIM) to estimate associations between exposure and lung function z-scores, adjusting for maternal/child characteristics, prenatal/postnatal tobacco exposure, and birth year/season, and evaluating effect modification by child sex and allergic sensitization.

RESULTS

The average ambient concentration of PM2.5 during pregnancy was 11.1 µg/m3 (standard deviation:1.0 µg/m3). In the adjusted linear regression and BDLIM models, adverse, but not statistically significant, associations were observed between exposure during the pseudoglandular (5-16 weeks of gestation) and saccular (24-36 weeks) phases of lung development and FEV1 and FVC. The strongest association was between a 2 μg/m3 higher concentration of PM2.5 during the saccular phase and FEV1 z-score (-0.176, 95% Confidence Interval [CI]: -0.361, 0.010). The FEV1/FVC ratio was not associated with PM2.5 in any exposure window. No effect modification by child sex or allergic sensitization was observed.

CONCLUSIONS

We did not find strong evidence of associations between prenatal ambient PM2.5 exposure and child lung function in a large, well-characterized study sample. However, there was a suggested adverse association between FEV1 and exposure during late pregnancy. The saccular phase of lung development might be an important window for exposure to PM2.5.