Updated reference values for static lung volumes from a healthy population in Austria.

BACKGROUND: Reference values for lung volumes are necessary to identify and diagnose restrictive lung diseases and hyperinflation, but the values have to be validated in the relevant population. Our aim was to investigate the Global Lung Function Initiative (GLI) reference equations in a representative healthy Austrian population and create population-derived reference equations if poor fit was observed. METHODS: We analysed spirometry and body plethysmography data from 5371 respiratory healthy subjects (6-80 years) from the Austrian LEAD Study. Fit with the GLI equations was examined using z-scores and distributions within the limits of normality. LEAD reference equations were then created using the LMS method and the generalized additive model of location shape and scale package according to GLI models. RESULTS: Good fit, defined as mean z-scores between + 0.5 and -0.5,was not observed for the GLI static lung volume equations, with mean z-scores > 0.5 for residual volume (RV), RV/TLC (total lung capacity) and TLC in both sexes, and for expiratory reserve volume (ERV) and inspiratory capacity in females. Distribution within the limits of normality were shifted to the upper limit except for ERV. Population-derived reference equations from the LEAD cohort showed superior fit for lung volumes and provided reproducible results. CONCLUSION: GLI lung volume reference equations demonstrated a poor fit for our cohort, especially in females. Therefore a new set of Austrian reference equations for static lung volumes was developed, that can be applied to both children and adults (6-80 years of age).

The effect of body compartments on lung function in childhood and adolescence.

BACKGROUND: There is an association between body composition and lung function, assessed by spirometry, but the effects of body compartments on static lung volumes and its changes during lung growth remain to be explored. We aimed to investigate the association of appendicular lean mass, reflecting skeletal muscle mass, and fat mass on forced and static lung function measures in childhood and adolescence. METHODS: In total, 1489 children and adolescents (6-18 years) of the observational, longitudinal (first and second visit within 4 years), general population-based LEAD study have been investigated. The association of appendicular lean mass and fat mass indices (ALMI and FMI; assessed by dual-energy X-ray absorptiometry) on lung function by spirometry (FEV1, FVC) and body plethysmography (TLC, RV, FRC) was investigated cross-sectionally. Longitudinal associations between lung function and body compartment changes between the two visits were analyzed. FINDINGS: The ALMI is positively associated with FEV1, FVC, and TLC. Contrary, FMI is inversely associated with lung function measures including FRC and RV. During the phase of lung growth, higher gain in muscle mass is associated with higher increases of FVC and TLC. INTERPRETATION: This study demonstrates the different effects of muscle and fat mass on forced expiratory and static lung volumes. Achieving and maintaining muscle mass in childhood and adolescence might become an important preventive strategy for lung health in adulthood.

Prevalence of dyspnea in general adult populations: A systematic review and meta-analysis.

INTRODUCTION: Dyspnea is a commonly described symptom in various chronic and acute conditions. Despite its frequency, relatively little is known about the prevalence and assessment of dyspnea in general populations. The aims of this review were: 1) to estimate the prevalence of dyspnea in general adult populations; 2) to identify associated factors; and 3) to identify used methods for dyspnea assessment. METHODS: A systematic literature search was conducted using MEDLINE/PubMed, Embase, CINAHL and JAMA network. Records were screened by two independent reviewers and quality was assessed by using the Joanna Briggs Institute checklist for risk of bias in prevalence studies. Multi-level meta-analysis was performed to estimate pooled prevalence. The protocol was registered on PROSPERO (CRD42021275499). RESULTS: Twenty original articles, all from studies in high-income countries, met the criteria for inclusion. Overall, their quality was good. Pooled prevalence of dyspnea in general adult populations based on 11 studies was 10% (95% CI 7, 15), but heterogeneity across studies was high. The most frequently reported risk factors were increasing age, female sex, higher BMI and respiratory or cardiac disease. The MRC or the modified MRC scale was the most used tool to assess dyspnea in general populations. CONCLUSIONS: Dyspnea is a common symptom in adults in high-income countries. However, the high heterogeneity across studies and the lack of data from low- and middle-income countries limit the generalizability of our findings. Therefore, more research is needed to unveil the prevalence of dyspnea and its main risk factors in general populations around the world.

Supranormal lung function: Prevalence, associated factors and clinical manifestations across the lifespan.

BACKGROUND AND OBJECTIVE: It is now well established that there are different life-long lung function trajectories in the general population, and that some are associated with better or worse health outcomes. Yet, the prevalence, clinical characteristics and risk factors of individuals with supranormal FEV1 or FVC values (above the upper-limit of normal [ULN]) in different age-bins through the lifetime in the general population are poorly understood. METHOD: To address these questions, we investigated the prevalence of supranormal FEV1 and FVC values in the LEAD (Lung, hEart, sociAl and boDy) study, a general population cohort in Austria that includes participants from 6 to 82 years of age. RESULTS: We found that: (1) the prevalence of supranormal pre-bronchodilator FEV1 and FVC values was 3.4% and 3.1%, respectively, and that these figures remained relatively stable through different age-bins except for participants >60 years., in whom they increased (5.0% and 4.2%, respectively). Approximately 50% of supranormal individuals had both increased FEV1 and FVC values; (2) supranormal spirometric values were consistently accompanied by higher static lung volumes and lower specific airway resistance through the lifespan, indicating better overall lung function; and (3) multivariate regression analysis identified that female sex, higher muscle mass (FFMI), less diabetes and fewer respiratory symptoms were consistently associated with supranormal FEV1 and FVC values. CONCLUSION: Supranormal FEV1 and/or FVC values occur in about 3% of the general population in different age bins and are associated with better health markers.

Prevalence of restrictive lung function in children and adults in the general population.

BACKGROUND: Restrictive lung function (RLF) is characterized by a reduced lung expansion and size. In the absence of lung volume measurements, restriction can be indirectly assessed with restrictive spirometric patterns (RSP) by spirometry. Prevalence data on RLF by the golden standard body plethysmography in the general population are scarce. Therefore, we aimed to evaluate the prevalence of RLF and RSP in the general population by body plethysmography and to determine factors influencing RLF and RSP. METHODS: Pre-bronchodilation lung function data of 8891 subjects (48.0% male, age 6-82 years) have been collected in the LEAD Study, a single-centered, longitudinal, population-based study from Vienna, Austria. The cohort was categorized in the following groups based on the Global Lung Initiative reference equations: normal subjects, RLF (TLC < lower limit of normal (LLN)), RSP (FEV1/FVC ≥ LLN and a FVC < LLN), RSP only (RSP with TLC ≥ LLN). Normal subjects were considered those with FEV1, FVC, FEV1/FVC and TLC between LLN and ULN (upper limit of normal). RESULTS: The prevalence of RLF and RSP in the Austrian general population is 1.1% and 4.4%. Spirometry has a positive and negative predictive value of 18.0% and 99.6% to predict a restrictive lung function. Central obesity was associated with RLF. RSP was related to smoking and underweight. CONCLUSIONS: The prevalence of true restrictive lung function and RSP in the Austrian general population is lower than previously estimated. Our data confirm the need for direct lung volume measurement to diagnose true restrictive lung function.