Lung Function Reference Values Research Articles

Development and validation of predictive equations for spirometry in Portuguese children.

There are no data on lung function reference values for Portuguese children, and the contribution from the Portuguese data set in the Global Lung Function Initiative (GLI) is scant. We aimed to estimate new up-to-date reference values for Portuguese children by fitting a multivariable regression model to a general population sample. Further, we intended to assess the external validity of the obtained reference values and to compare them to the GLI reference values. A random sample of 858 children from 20 primary schools were screened by health questionnaire, physical examination, and spirometry. Spirometric parameters recorded were FVC, FEV1, and FEF25-75. Multiple regression models were used to derive reference equations. Overall, 481 children, aged between 7 and 12 years, 267 boys (55.5%), were included. Boys had higher values for FVC and FEV1 than girls (P< .05). The strongest correlation was found for FVC with height (r= 0.71 for boys and 0.70 for girls), while the lowest correlation was observed in both sexes for FEF25-75 with age (r= 0.23). Height was the most significant predictor of FVC, FEV1, and FEF25-75 in our models. Weight and body mass index were not significant predictors for boys but had a significant effect on girls' equations for all spirometry parameters. Compared to obtained reference equations with GLI, they performed better for FVC in boys, FEV1 in girls, and FEF25-75 in both boys and girls. We offer up-to-date reference values of spirometry for Portuguese children that can be used in clinical practice and research.

Comparison of different reference values for lung function: implications of inconsistent use among centers

BackgroundFor interpretation of pulmonary function tests (PFTs), reference values based on sex, age, height and ethnicity are needed. In Norway, the European Coal and Steel Community (ECSC) reference values remain widely used, in spite of recommendations to implement the more recent Global Lung Function Initiative (GLI) reference values.ObjectiveTo assess the effects of changing from ECSC to GLI reference values for spirometry, DLCO and static lung volumes, using a clinical cohort of adults with a broad range in age and lung function.MethodsPFTs from 577 adults (18–85 years, 45% females) included in recent clinical studies were used to compare ECSC and GLI reference values for FVC, FEV1, DLCO, TLC and RV. Percent predicted and lower limit of normal (LLN) were calculated. Bland-Altman plots were used to assess agreement between GLI and ECSC % predicted values.ResultsIn both sexes, GLI % predicted values were lower for FVC and FEV1, and higher for DLCO and RV, compared to ECSC. The disagreement was most pronounced in females, with mean (SD) difference 15 (5) percent points (pp) for DLCO and 17 (9) pp for RV (p < 0.001). With GLI, DLCO was below LLN in 23% of the females, with ECSC in 49% of the females.ConclusionsThe observed differences between GLI and ECSC reference values are likely to entail significant consequences with respect to criteria for diagnostics and treatment, health care benefits and inclusion in clinical trials. To ensure equity of care, the same reference values should be consistently implemented across centers nationwide.

Differences in the Spirometry Parameters Between Indigenous and Non-Indigenous Patients with COPD: A Matched Control Study.

BackgroundComparison of spirometry parameters between Indigenous and non-Indigenous patients with underlying chronic obstructive pulmonary disease (COPD) has been sparsely reported in the past. In this study, differences in the lung function parameters (LFPs), in particular spirometry values for forced vital capacity (FVC), forced expiratory volume in one second (FEV1) and FEV1/FVC ratio between Indigenous and non-Indigenous patients with COPD were assessed.MethodsIn this retrospective study, Indigenous and non-Indigenous patients with a diagnosis of COPD between 2012–2020 according to spirometry criteria (ie; post-bronchodilator (BD) FEV1/FVC < 0.7) were included. A further analysis was undertaken to compare the differences in the spirometry parameters, including lower limit of normal (LLN) values matching for age, sex, height and smoking status between these two diverse ethnic populations.ResultsA total of 240/742 (32%) Indigenous and 873/4579 (19%) non-Indigenous patients were identified to fit the criteria for COPD. Indigenous patients were significantly younger (mean difference 9.9 years), with a greater proportion of females (50% vs 33%), underweight (20% vs 8%) and current smokers (47% vs 32%). Prior to matching, Indigenous patients’ post-BD percent predicted values for FVC, FEV1, and FEV1/FVC ratio were 17, 17%, and −2 points lower (Hedges G measure of effect size large (0.91), large (0.87), and small (0.25), respectively). Among the matched cohort (111 Indigenous and non-Indigenous), Indigenous patients LFPs remained significantly lower, with a mean difference of 16%, 16%, and −4, respectively (Hedges G large (0.94), large (0.92) and small (0.41), respectively). The differences persisted despite no significant differences in LLN values for these parameters.ConclusionIndigenous Australian patients with COPD display a significantly different demographic and clinical profile than non-Indigenous patients. LFPs were significantly lower, which may or may not equate to greater severity of disease in the absence of normative predictive lung function reference values specific to this population.

A comparative analysis of lung function and spirometry parameters in genotype-controlled natives living at low and high altitude

BackgroundThe reference values for lung function are associated to anatomical and lung morphology parameters, but anthropometry it is not the only influencing factor: altitude and genetics are two important agents affecting respiratory physiology. Altitude and its influence on respiratory function has been studied independently of genetics, considering early and long-term acclimatization.ObjectiveThe objective of this study is to evaluate lung function through a spirometry study in autochthonous Kichwas permanently living at low and high-altitude.MethodologyA cross-sectional study of spirometry differences between genetically matched lowland Kichwas from Limoncocha (230 m) at Amazonian basin and high-altitude Kichwas from Oyacachi (3180 m) in Andean highlands. The sample size estimates permitted to recruited 118 patients (40 men and 78 women) from Limoncocha and 95 (39 men and 56 women) from Oyacachi. Chi-square method was used to analyze association or independence of categorical variables, while Student’s t test was applied to comparison of means within quantitative variables. ANOVA, or in the case that the variables didn’t meet the criteria of normality, Kruskal Wallis test were used to compare more than two groups.ResultsThe FVC and the FEV1 were significantly greater among highlanders than lowlanders (p value < 0.001), with a proportion difference of 15.2% for men and 8.5% for women. The FEV1/FVC was significantly higher among lowlanders than highlanders for men and women. A restrictive pattern was found in 12.9% of the participants.ConclusionResidents of Oyacachi had greater FVC and FEV1 than their peers from Limoncocha, a finding physiologically plausible according to published literature. Lung size and greater ventilatory capacities could be an adaptive mechanism developed by the highlander in response to hypoxia. Our results support the fact that this difference in FVC and FEV1 is a compensatory mechanism towards lower barometric and alveolar partial pressure of oxygen pressure.

Factors Affecting Lung Function: A Review of the Literature

Lung function reference values are traditionally based on anthropometric factors, such as weight, height, sex, and age. FVC and FEV1 decline with age, while volumes and capacities, such as RV and FRC, increase. TLC, VC, RV, FVC and FEV1 are affected by height, since they are proportional to body size. This means that a tall individual will experience greater decrease in lung volumes as they get older. Some variables, such as FRC and ERV, decline exponentially with an increase in weight, to the extent that tidal volume in morbidly obese patients can be close to that of RV. Men have longer airways than women, causing greater specific resistance in the respiratory tract. The increased work of breathing to increase ventilation among women means that their consumption of oxygen is higher than men under similar conditions of physical intensity. Lung volumes are higher when the subject is standing than in other positions. DLCO is significantly higher in supine positions than in sitting or standing positions, but the difference between sitting and standing positions is not significant. Anthropometric characteristics are insufficient to explain differences in lung function between different ethnic groups, underlining the importance of considering other factors in addition to the conventional anthropometric measurements.

Factores que afectan a la función pulmonar: una revisión bibliográfica

Lung function reference values are traditionally based on anthropometric factors, such as weight, height, sex, and age. FVC and FEV1 decline with age, while volumes and capacities, such as RV and FRC, increase. TLC, VC, RV, FVC and FEV1 are affected by height, since they are proportional to body size. This means that a tall individual will experience greater decrease in lung volumes as they get older. Some variables, such as FRC and ERV, decline exponentially with an increase in weight, to the extent that tidal volume in morbidly obese patients can be close to that of RV. Men have longer airways than women, causing greater specific resistance in the respiratory tract. The increased work of breathing to increase ventilation among women means that their consumption of oxygen is higher than men under similar conditions of physical intensity. Lung volumes are higher when the subject is standing than in other positions. DLCO is significantly higher in supine positions than in sitting or standing positions, but the difference between sitting and standing positions is not significant. Anthropometric characteristics are insufficient to explain differences in lung function between different ethnic groups, underlining the importance of considering other factors in addition to the conventional anthropometric measurements.

The Global Lung Function Initiative (GLI) Network: bringing the world's respiratory reference values together.

The Global Lung Function Initiative (GLI) Network has become the largest resource for reference values for routine lung function testing ever assembled. This article addresses how the GLI Network came about, why it is important, and its current challenges and future directions. It is an extension of an article published in Breathe in 2013 [1], and summarises recent developments and the future of the GLI Network.Key pointsThe Global Lung Function Initiative (GLI) Network was established as a result of international collaboration, and altruism between researchers, clinicians and industry partners. The ongoing success of the GLI relies on network members continuing to work together to further improve how lung function is reported and interpreted across all age groups around the world.The GLI Network has produced standardised lung function reference values for spirometry and gas transfer tests.GLI reference equations should be adopted immediately for spirometry and gas transfer by clinicians and physiologists worldwide.The recently established GLI data repository will allow ongoing development and evaluation of reference values, and will offer opportunities for novel research.Educational aimsTo highlight the advances made by the GLI Network during the past 5 years.To highlight the importance of using GLI reference values for routine lung function testing (e.g. spirometry and gas transfer tests).To discuss the challenges that remain for developing and improving reference values for lung function tests.

South African and International Reference Values for Lung Function and its Relationship with Blood Pressure in Africans

In South Africa respiratory diseases are highly prevalent, with cardiovascular disease being a manifestation. However, international reference values for lung function are commonly used, which may not be appropriate to correctly identify reduced lung function. An inverse relationship exists between lung function and blood pressure (BP) but is not investigated extensively in black South Africans. We included 2010 Africans from the PURE (Prospective Urban Rural Epidemiology) study (aged > 35 years) in the North West Province. Spirometry was performed and predicted values for forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) were calculated from South African, European and United States prediction equations. With the exception of the European predicted values, all other predicted mean FEV1 and FVC were above 80%. South African reference values displayed the highest percentages of the predicted values for FEV1 and FVC (87.9 and 99.7%, respectively.) BP increased from quintiles five to one for both FEV1 and FVC, (p for trend <0.001). After adjustment the differences remained (p<0.05). South African reference values yielded higher percentages of predicted FEV1 and FVC values than European and US equations suggesting that South African prediction equations may be more useful when investigating lung function in black South Africans. Elevated BP is related to reduced lung function, highlighting the importance in managing both respiratory- and cardiovascular disease.

FEV1 and FVC pulmonary function reference values among 6-18-year-old children: a multi-centre study in Saudi Arabia

It is important to establish lung function reference values for each population. This study aimed to determine the spirometric reference values for healthy Saudi Arabian children and adolescents and to derive prediction equations for these. A cross-sectional study was conducted among healthy schoolboys and girls aged 6-18 years old, selected randomly from the 6 administrative regions of Saudi Arabia. Data were collected by questionnaire and physical examinations including spirometry. Forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) were significantly higher in males than females. Height was the anthropometric variable most strongly correlated with FEV1 (r = 0. 61), more so for males (r = 0.71) than females (r = 0.50). In males the multivariate linear regression model explained 53.9% of FEV1 and 35.1% of FVC variations. In females it explained 25.3% of FEV1 and 16.5% of FVC variations. All changes in R² were statistically significant.

New Danish reference values for spirometry

International recommendations state that reference values for lung function should derive from cross-sectional studies of healthy nonsmokers and be renewed from time to time because of cohort effect and newer, more accurate, technical equipment. In 1986, the Danish Lung Society published reference values for spirometry based on 570 individuals aged 30-70 years. To produce new reference values for lung function and to extend the existing values by including individuals between 20 and 30 years of age and older than 70 years of age. Two similar but independent studies was used: The 2001-2003 examination of the Copenhagen City Heart Study and the 2003–2010 examination of the Copenhagen General Population Study. Of a total of 69 822 individuals, we included 11 288 healthy never-smoking white individuals to produce the reference values: 6307 women and 4981 men, 20 years of age or older with adequate lung function. We used sex-stratified multiple linear regression analysis to find prediction formulas for forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC) and FEV1/FVC adjusted for age and height. The cutoff value of normal lung function was defined as the fifth percentile (also named the 5% quantile) according to gender, age and height. The robustness of the data was tested and validated in several ways. Compared with the 1986 data, our 2001–2010 material contributes with a substantial number of individuals in the more extreme groups of age and height, and in general, our dataset shows that in most subgroups, the lung function level has improved during the last two decades.

Reference values for lung function: past, present and future

Reliable interpretation of pulmonary function results relies on the availability of appropriate reference data to help distinguish between health and disease and to assess the severity and nature of any functional impairment. The overwhelming number of published reference equations, with at least 15 published for spirometry alone in the past 3 yrs, complicates the selection of an appropriate reference. The use of inappropriate reference equations and misinterpretation, even when potentially appropriate equations are used, can lead to serious errors in both under and over diagnosis, with its associated burden in terms of financial and human costs. Further misdiagnosis occurs when fixed cut-offs, such as 80% predicted forced expiratory volume in 1 s (FEV(1)) or 0.70 FEV(1)/forced vital capacity, are used; particularly in young children and elderly adults. While per cent predicted has historically been used to interpret lung function results, z-scores are more appropriate as they take into account the predicted value, as well as the between-subject variability of measurements. We aim to highlight some of the main issues in selecting and using reference equations and discuss how recent developments may improve interpretation of pulmonary function results.

Lung Function Reference Values in Children and Adolescents Aged 6 to 18 Years in Galicia

It is well known that lung function reference values differ between populations, hence the apparent importance of establishing such values. The aim of this study was to develop prediction equations for spirometry for healthy children and adolescents in Galicia, Spain. We studied children and adolescents aged 6 to 18 years from randomly selected schools in 14 municipalities in Galicia. Spirometric values were measured following the protocols established by the American Thoracic Society in 1987, with real-time monitoring of flow-volume curves. The prediction equations were derived using multivariate linear regression. We developed equations to predict the main spirometry parameters for this age group according to sex, height, and weight. Mean spirometry values in relation to height were higher for boys than for girls, except in the 140-160 cm range, where they were higher for girls. Equations published in other studies in similar populations gave different predictions, ranging from an underestimation of forced midexpiratory flow rate (FEF(25%-75%)) by 16% in comparison to ours to an overestimation of peak expiratory flow (PEF) rate by 15% for an average boy. For a girl, the corresponding differences ranged from an underestimation of FEF(25%-75%) by 17% to an overestimation of PEF by 19%. These results support the importance of using population-specific prediction equations to establish lung function reference values.

Lung function reference values in Chinese children and adolescents in Hong Kong. II. Prediction equations for plethysmographic lung volumes.

As part of a comprehensive evaluation of lung function in Hong Kong Chinese children and adolescents, over a thousand healthy subjects aged 7-19 yr from seven schools were recruited for lung function testing that included spirometry and, in many cases, lung subdivision measurements. Lung function tests were performed using SensorMedics Automated Body Plethysmograph according to published standards. Of these, 551 subjects (219 males), aged 8-19 yr, had satisfactory lung subdivision indices recorded. Analysis for the values of lung subdivisions including total lung capacity (TLC), residual volume (RV), and functional residual capacity (FRC) demonstrated that standing height and sitting height were the best predictors of lung volumes. After allowing for standing height or sitting height in the regression models for lung volumes, age at examination was the second best parameter, although its inclusion into the equations contributed to less than 1% of explained variance for boys and 3% for girls. These are the first reported data in international literature on reference values for lung subdivisions in Chinese children and adolescents.

References values for forced spirometry. Group of the European Community Respiratory Health Survey.

The European Coal and Steel Community (ECSC) prediction equations exemplify a significant effort carried out approximately 15 yrs ago to provide uniform standards for lung function testing, but this set of equations has not been properly validated as yet. The present study evaluates the ECSC reference values and four other sets of prediction equations, using spirometric data collected in 12,900 nonasthmatic subjects (43% lifetime nonsmokers and 36% active smokers) aged 20-44 yrs from the European Community Respiratory Health Survey (ECRHS). Standardized spirometric measurements were obtained using a common protocol in 34 centres in 14 countries. For each prediction equation, the prediction deviations (i.e. observed minus predicted value) for forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) were examined for the whole study population and for each centre. For the age range included, the errors about the ECSC equations showed the most prominent underestimation of both predicted FVC (+355 and +360 mL on average in males and females, respectively) and predicted FEV1 (+211 and +200 mL, respectively) among the five studies examined. As expected, FVC and FEV1 in active smokers from the ECRHS were significantly lower than in lifetime nonsmokers (each p<0.01). We conclude that the present European recommendations on lung function reference values should be reconsidered, but further data for nonsymptomatic subjects above the age of 44 yrs are needed.

Lung function reference values in Singaporean children aged 6-18 years.

A study was undertaken to produce reference values of lung function in Chinese children and a means of calculating adjusted standard deviation scores of lung function for Malay and Indian ethnic groups. A cross sectional study of lung function (forced expiratory volume in one second and forced vital capacity) measured with a Jaeger spirometer was performed in a representative sample of Singaporean children made up of 1403 Chinese, 335 Malays, and 206 Indians. The relation between natural logarithms of lung function and height was approximately linear until 150 cm in boys and 140 cm in girls. At these heights there were abrupt changes in the gradients of both lines. Separate regression lines were derived for heights above and below these inflection points. Significant differences in lung function were seen in Chinese compared with Malay and Indian children. In particular, values were considerably lower among Indian boys. The relation between lung function and height in Chinese children is best described by two regression equations over separate height ranges. Information is provided for the calculation of reference values and standard deviation scores, together with the correction factors that need to be applied to derive these values in Malay and Indian children.

Ventilatory standards for clinically well aboriginal adults.

To obtain reference standards for ventilatory function of clinically well Australian Aboriginal adults. A cross-sectional assessment of the population of a North Queensland Aboriginal community. A specialist clinical and public health service. The measurements were made with the cooperation of the local primary health care centre. The 288 study subjects included over 70% of Aboriginal adults residing in an isolated Cape York community. Those with known respiratory disease, abnormal chest x-ray findings, positive loose cough sign, abnormal lung signs or inability to perform the ventilatory tests satisfactorily were excluded; 229 persons (80%) remained for analysis. Smoking was prevalent in both men (85%) and women (76%). As in most other studies producing reference values for lung function, smokers were not excluded. Age, standing height in bare feet and sitting height were recorded. Ventilatory measurements included forced expiratory volume in one second (FEV1), forced vital capacity (FVC) and maximum mid-expiratory flow (MMEF) which is also known as the forced expiratory flow (FEF 25%-75%). Standing height, age and sex were the major determinants of ventilatory function. Sitting height was not a good predictor. Ventilatory values differed significantly from those expected for Europeans: Aboriginal lung volumes were much smaller (by about 25%) and fell much faster with age. The age-related decrease in lung function was less in smokers. The smoking effect may reflect the operation of differential survival or other selective factors and has been noted in some other ethnic groups. Although previous studies have yielded some ventilatory function data on Aborigines, we report the first population-based reference values expected for clinically well adults. The information will be useful to clinicians and public health workers.

Reference values and prediction equations for normal lung function in a non-smoking white urban population.

Prediction equations for normal lung function have been derived from tests on 179 healthy, non-smoking, white urban dwellers. The subjects, 96 women (height 1.46-1.77 m) and 83 men (height 1.61-1.96 m) aged 18-86 years, underwent measurements of spirometric flow and volume, multi-breath helium dilution lung volumes, and single breath carbon monoxide transfer factor and the single breath nitrogen washout test. Regression analysis using height, age, and weight as independent variables was used to provide predicted values for both sexes. Correlation coefficients were similar to those found in previous studies but normal ranges for spirometic measurements were narrower than in many previous studies, and spirometric flow and volume measurements were higher than those obtained in studies that included cigarette smokers, reflecting our more stringent criteria for selecting subjects and the newer standardised technical methods adopted. Multi-breath helium dilution values for total lung capacity were similar to those found in previous studies but the inspiratory vital capacity was larger and the residual volume reduced. Values for carbon monoxide transfer factor and the single breath nitrogen washout did not differ significantly from existing values. A complete set of lung function reference values and prediction equations for both sexes has been derived from a single population. The exclusion of cigarette smokers and subjects with respiratory symptoms has produced values that should have a greater sensitivity in the detection of mild lung disease.

Lung function in healthy British women.

The forces expiratory volume, total lung capacity, transfer factor (diffusing capacity), and their subdivisions have been measured in 113 healthy British women aged 27 to 74 years of whom 47 were current smokers and 66 were lifetime non-smokers. The results have been analysed in terms of age, stature, mass, body fat, and smoking. In addition to their relation to stature and to age, the inspiratory capacity was positively correlated with indices of body muscle while the residual volume, expiratory reserve volume, and total lung capacity were inversely correlated with the percentage of body mass that is fat or with mass divided by the square of stature. The inverse correlation between total lung capacity and age was apparently due to the quantity of body fat increasing with age. The transfer factor and its subdivisions were inversely correlated with smoking. In this study the forced expiratory volume and vital capacity were independent of both fat and smoking; the transfer factor was independent of the physiological response to exercise. The results provide reference values for lung function in British women.