Spirometric Reference Equations Research Articles

Spirometric reference equations and lung function testing in adults from Southwestern Tanzania.

The increasing relevance of lung function testing in diagnosing and treating pulmonary diseases globally requires adequate spirometric reference equations. However, locally derived reference standards from African countries are widely missing. This cross-sectional study was conducted in Southwestern Tanzania. Participants underwent a socio-demographic interview, anthropometric measurements and standardised spirometric lung function testing. Regression modelling was used to generate Tanzanian prediction equations for spirometry parameters forced vital capacity (FVC), forced expiratory volume in 1 sec (FEV1) and the FEV1/FVC ratio. Out of 400 recruited participants, 343 had usable spirometry results with respect to the American Thoracic Society (ATS)/European Respiratory Society (ERS) reproducibility and acceptability criteria. The mean age of participants was 32.65 years (SD 12.11), and 44,9% were females. Spirometric parameters increased with height but decreased with older age. The coefficients of our new prediction equations for spirometry parameters differed substantially from those of existing reference standards. This study provides prediction equations for spirometric lung function in a non-smoking Tanzanian population. The differences in existing equations underline the heterogeneity of locally derived reference equations in Africa and contribute insights and data to discussing global respiratory health care reference standards.

Comparison of race-specific and race-neutral GLI spirometric reference equations with an Indian reference equation

BackgroundDespite the increasing popularity and use of Global Lung Function Initiative (GLI) spirometric reference equations, the appropriateness of the race-specific and race-neutral GLI spirometric reference models among the Indian population has not been systematically investigated. MethodsIn this cross-sectional analysis, we used spirometric measurements of 1123 healthy Indian adults (≥18 years of age). We computed reference values and z-scores for forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), and FEV1/FVC from race-specific and race-neutral GLI reference equations as well as from a widely used Indian reference equation. We studied heterogeneity between GLI equations and the Indian equations using Bland-Altman analysis, and the differences between the reference and observed values were compared using the Friedman test. ResultsIn Bland-Altman analysis, significant heterogeneity in FVC and FEV1 between race-specific and Indian equations was observed (bias: 10.4 % and 14.1 %, respectively), with less bias for FEV1/FVC (3.76 %). The race-neutral equations showed almost similar bias (9.8 %, 13.8 %, and 3.8 % for FVC, FEV1, and FEV1/FVC, respectively). Median differences in race-specific reference values from observed values for FVC and FEV1 were 0.49L and 0.44L, respectively, decreasing slightly with race-neutral equations (0.46L and 0.43L) whereas Indian models showed minimal differences (FVC: 0.10L, FEV1: 0.05L). Z-scores for FVC and FEV1 were significantly different between race-specific and race-neutral GLI equations, and both differed from Indian equations. ConclusionBoth race-specific and race-neutral GLI reference equations are significantly different from the Indian equations, which underscores the importance of determining the suitability of global reference models before being used indiscriminately.

History of spirometric and plethysmographic reference equations in Algeria

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Race-neutral equations for assessment of lung function in children with thalassemia.

The aim of this study was to assess pulmonary dysfunction in children with transfusion-dependent thalassemia (TDT) using the Global Lung Function Initiative (GLI) 2022 race-neutral spirometric reference equations and to determine the main predicting factors. The spirometric results of 68 children with TDT were compared to the results of 68 healthy control subjects using both GLI-2012 reference equations for Caucasians and GLI-2022 global equations. Associations between the spirometric data and various anthropometric, clinical, and laboratory parameters were analyzed to detect predictors of pulmonary dysfunction in this group of patients. Children with TDT showed significantly lower values of FVC and FEV1 with a predominance of the restrictive pattern (23.53%). Thalassemic children with the restrictive pattern were significantly older, had a longer duration of regular blood transfusion, lower height, weight, and BMI z-scores, higher average serum ferritin, and higher frequency of having a serum ferritin level >2500 ng/mL. The strongest predictor for having a restrictive spirometric pattern was high serum ferritin. Our analysis shows that the transition from GLI-2012 spirometric reference equations for Caucasians to the GLI-2022 global equations has led to a reduction in the prevalence rate of restrictive pulmonary dysfunction in children with TDT, which should not affect the patient outcome in the long term. Asymptomatic children with TDT exhibited a restrictive spirometric pattern in a significant proportion. The most important predictor was high serum ferritin. We encourage the inclusion of pulmonary function testing in the routine monitoring of patients with TDT, especially in older patients and those with iron overload.

Diffusing capacity of lungs in chronic obstructive pulmonary disease: gender, age, and race aspects

Introduction. Diffusion capacity of lungs is the second most important respiratory test after spirometry. The importance of assessing lung diffusion capacity in chronic obstructive pulmonary disease (COPD) is not given due attention, although this parameter reflects changes in functional lung volume and gas transport through the alveolar-capillary membrane, thereby providing more information about respiratory physiology than spirometry results. Diffusing capacity of the lung for carbon monoxide (DLCO) measurement is the standard in pulmonology, however, in recent years, close attention has been given to the determination of lung diffusion capacity for nitric oxide (DLNO), which gives better explanation of gas transport through the alveolar-capillary membrane compared to DLCO. Recent literature is actively discussing the inclusion of age, race, and gender aspects in spirometric reference equations that are used to assess spirometric parameters and lung diffusion capacity.Aim. To analyze the literature over the past five years, reflecting the views of modern researchers on methods for diagnosing lung diffusion capacity, as well as the contribution of age, race, and gender aspects to the assessment of this parameter in COPD.Materials and methods. The PubMed database was searched for information for the period 2017-2022 according to the selected inclusion criteria. Information requests included the following set of keywords: “diffusion capacity”, “chronic obstructive pulmonary disease”, “gender”, “age”, “race”, “DLNO”, “DLCO”. 123 articles were analyzed.Results. Recent evidence highlights the importance of including lung diffusivity in COPD prognostic programs. Determining the diffusion capacity of the lungs for nitric oxide may be a promising area of research soon. Gender and age considerations play an important role in the interpretation of spirometry data and lung diffusion capacity. The issue of including a racial trait in the assessment of the diffusing capacity of the lungs in COPD is in doubt.

Spirometric reference equations for Cameroonians aged 4 to 89\xa0years derived using lambda, mu, sigma (LMS) method

BackgroundSpirometric reference values are well known in several ethnic groups but the normative spirometric values of blacks living in Africa have been less studied. The purpose of this study is to establish normative spirometric equations from a representative population of Cameroonian children and adults and compare these equations with those developed by the Global Lung Initiative (GLI) and in Nigerians.MethodsSpirometric data from healthy Cameroonians aged 4–89 years randomly collected between 2014 and 2018 were used to derive reference equations using generalized additive model for location (mu), shape (lambda) and scale (sigma).ResultsA total of 625 children and adolescents (290 males and 335 females) and 1152 adults (552 males and 600 females) were included in the study. The prediction equation for spirometric index was written as: M = Exp[a0 + a1*ln (Height) + a2*ln (Age) + Mspline, Mspline was age related spline contribution]. Applying the GLI standards for African Americans resulted in overall values greater than those found in our study for forced expiratory volume in 1s (FEV1) and forced vital capacity (FVC). These values were very close in children and adolescents while the values obtained with the GLI equations for African Americans were significantly higher in adults. FEV1/FVC ratio in our study was similar for adult males but lower in adult females (88% vs 85%, difference = + 3.5%) when applying Nigerian standards.ConclusionsFEV1 and FVC of the Cameroonian infant and adolescent population are very close to those of black Americans. However, FEV1 and FVC of Cameroonian adults are significantly lower than those of black American adults. These equations should allow a more suitable interpretation of spirometry in the Cameroonian population.

Spirometry reference equations for children from a Middle Eastern population.

Spirometry is a clinically useful test that can be used to assess lung function among children. Different equations had been formulated to determine the spirometric reference values depending on several individual characteristics. However, the widely used equations do not produce perfect suitability for Middle Eastern children. This study aims to formulate Middle Eastern-specific equations that may be applicable for other populations in the region. The spirometric data were collected from Jordanian children between the ages of 6 and 17 years. The collected data were used to formulate customised reference equations for Middle Eastern children using generalised additive models for location, scale and shape. The newly formulated equation results were compared with Global Lung Initiative 2012 (GLI-2012) equations predicted values. Spirometric values for 1576 healthy participants (870 males) were used to formulate the new equations. The assessment of z-scores produced by the present study equations and GLI-2012 indicated that the new equations were more suitable than GLI-2012 for Middle Eastern children. In-depth analysis of the results indicated that the suitability of GLI-2012 equations varied between different age points. This study formulated new spirometric reference equations for Middle Eastern children that can improve the diagnosis and management of different respiratory conditions.

Development of spirometric reference equations for children living at high altitude.

This study was aimed to provide locally derived spirometric equations from a population of healthy children residing in Bogota, Colombia, a high-altitude city. Healthy children aged more than 6years up to less than 18years underwent spirometry from January 2017 to January 2018, following the recommendations made by the American Thoracic Society/European Respiratory Society (ATS/ERS) Task Force. We performed stepwise multiple regression analyses to predict each spirometric parameter. We also performed extensive residual analyses comparing the measured values with those calculated with our new spirometric equations and with other commonly used equations. Predictive equations for each spirometric variable were derived from 326 spirometric tests (149 boys, 177 girls). Our newly derived spirometric equations provided the minimum of median of prediction error for almost all spirometric indices measured. We recommend the newly developed spirometric equations for assessing the ventilatory function of children living in Bogota, Colombia.

Changes In Pulmonary Function In Us Firefighters Over A 5-year Period

Acute and chronic changes in pulmonary function have been previously reported in US firefighters. However, the majority of research on pulmonary function in US firefighters was conducted more than three decades ago. Due to the changes in the use of protective equipment and changes in materials that are burning in structure fires, it is important to examine pulmonary function in firefighters and to explore changes in pulmonary function over time. PURPOSE: To examine pulmonary function and changes in pulmonary function over a 5-year period in US firefighters. METHODS: Occupational medical exams separated by 5 years (2009-2016) were examined from a cohort of US career firefighters in Virginia (males, n=603; females, n=69). The exam results were compared to the expected changes over time based on spirometric reference equations generated from NHANES III data. Paired t-tests were used to compare observed changes between Time 1 and Time 2. One-sample t-tests were used to compare the expected with the observed change. RESULTS: There were significant decreases (p<0.001) in FEV1, FVC, and FEV1/FVC over the 5-year period. There were significant differences (p<0.001) between observed changes in FEV1, FVC, and FEV1/FVC and the expected changes over a 5-year period (Table). CONCLUSION: Pulmonary function declined significantly over time. The observed decreases over the 5-year period in FEV1, FVC, and FEV1/FVC were two to four times greater than what would be expected in the general population. Increased efforts are needed to address respiratory protection for US firefighters in order to minimize their risk of pulmonary illnesses and occupational cancer. Supported by FEMA AFG Grant EMW 2017-FP-00445.Table: 5-Year Changes in Pulmonary Measurements Among US Firefighters

Validation of the global lung initiative 2012 multi-ethnic spirometric reference equations in healthy urban Zimbabwean 7\u201313\u2009year-old school children: a cross-sectional observational study

BackgroundThe 2012 Global Lung Function Initiative (GLI2012) provide multi-ethnic spirometric reference equations (SRE) for the 3–95 year-old age range, but Sub-Saharan African populations are not represented. This study aimed to evaluate the fit of the African-American GLI2012 SRE to a population of healthy urban and peri-urban Zimbabwean school-going children (7–13 years).MethodsSpirometry and anthropometry were performed on black-Zimbabwean children recruited from three primary schools in urban and peri-urban Harare, with informed consent and assent. Individuals with a history or current symptoms of respiratory disease or with a body mass index-z score (BMI) < − 2 were excluded. Spirometry z-scores were generated from African-American GLI2012 SRE, which adjust for age, sex, ethnicity and height, after considering all GLI2012 modules. Anthropometry z-scores were generated using the British (1990) reference equations which adjust for age and sex. The African-American GLI2012 z-score distribution for the four spirometry measurements (FVC, FEV1, FEV1/FVC and MMEF) were evaluated across age, height, BMI and school (as a proxy for socioeconomic status) to assess for bias. Comparisons between the African-American GLI2012 SRE and Polgar equations (currently adopted in Zimbabwe) on the percent-predicted derived values were also performed.ResultsThe validation dataset contained acceptable spirometry data from 712 children (344 girls, mean age: 10.5 years (SD 1.81)). The spirometry z-scores were reasonably normally distributed, with all means lower than zero but within the range of ±0.5, indicating a good fit to the African-American GLI2012 SRE. The African-American GLI2012 SRE produced z-scores closest to a normal distribution. Z-scores of girls deviated more than boys. Weak correlations (Pearson’s correlation coefficient < 0.2) were observed between spirometry and anthropometry z-scores, and scatterplots demonstrated no systematic bias associated with age, height, BMI or socioeconomic status. The African-American GLI2012 SRE provided a better fit for Zimbabwean paediatric spirometry data than Polgar equations.ConclusionThe use of African-American GLI2012 SRE in this population could help in the interpretation of pulmonary function tests.

Validation of Previous Spirometric Reference Equations and New Equations.

BackgroundPulmonary functions are interpreted using predicted values from reference equations that vary with ethnicity, gender, age, height, and weight. The universally used Choi's reference equations are not validated for Korean populations, and the purpose of this study was to validate them and develop new reference equations.MethodsSubjects with normal spirometry and chest radiographs, no co-morbidities, and non-smokers, from the Korean National Health and National Examination Survey (KNHANES)-VI were enrolled (n = 117). Intraclass correlation coefficient (ICC) was assessed for reliability of reference equations. New reference equations were developed using linear regression analysis. Differences between observed and predicted values were assessed to compare the reference equations from Choi's, Global Lung Function Initiative 2012, KNHANES-IV, and newly developed equations.ResultsThe ICC of Choi's reference equations was 0.854 (P < 0.001). The new reference equations for men were: forced vital capacity (FVC) (L) = − 4.38775 − 0.01184 × age + 0.05547 × height, forced expiratory volume – 1 second (FEV1) (L) = − 2.40147 − 0.02134 × age + 0.04103 × height; and for women: FVC (L) = − 3.09063 + 0.003904 × age + 0.038694 × height; FEV1 (L) = − 1.32933 − 0.00872 × age + 0.02762 × height. The differences between the predicted and observed means were largest in Choi's equations, but lowest in the new equations with highest goodness of fit.ConclusionBecause Choi's reference equations presented larger differences from the observed values, despite reliability, and the new reference equations showed better goodness of fit, we suggest the latter for Korean populations.

Espirometría: Manual de procedimientos. SERChile

Spirometry is a basic test for assessing pulmonary function. This test is largely used nowadays, because of its low cost and acceptable reproducibility. Its feasibility has been shown even in 2 to 6 year old children. Considering the importance of applying standardized techniques in spirometry, a committee of specialists on pulmonary function from Chilean Respiratory Society, published in 2006 a procedures manual on spirometry. By 2014 new spirometric reference equations for healthy Chilean adults were published and more recently in 2017, the American Thoracic Society and the European Respiratory Society have published recommendations for a standardized pulmonary function report. The aim of this manual is to report international norms performing spirometry, in order to promote their application in clinical and laboratory practice. In addition, this reviewed manual encloses newest concepts on spirometry in preschool children, reference values, and a general assent way for interpreting and reporting spirometric values at clinical and at laboratory work is proposed.

Spirometric Reference Equations for Elderly Chinese in Jinan Aged 60-84 Years.

Background:The interpretation of spirometry varies on different reference values. Older people are usually underrepresented in published predictive values. This study aimed at developing spirometric reference equations for elderly Chinese in Jinan aged 60–84 years and to compare them to previous equations.Methods:The project covered all of Jinan city, and the recruitment period lasted 9 months from January 1, 2017 to September 30, 2017, 434 healthy people aged 60–84 years who had never smoked (226 females and 208 males) were recruited to undergo spirometry. Vital capacity (VC), forced VC (FVC), forced expiratory volume in 1 s (FEV1), FEV1/FVC, FEV1/VC, FEV6, peak expiratory flow, and forced expiratory flow at 25%, 50%, 75%, and 25–75% of FVC exhaled (FEF25%, FEF50%, FEF75%, and FEF25–75%) were analyzed. Reference equations for mean and the lower limit of normal (LLN) were derived using the lambda-mu-sigma method. Comparisons between new and previous equations were performed by paired t-test.Results:New reference equations were developed from the sample. The LLN of FEV1/FVC, FEF25–75% computed using the 2012-Global Lung Function Initiative (GLI) and 2006-Hong Kong equations were both lower than the new equations. The biggest degree of difference for FEV1/FVC was 19% (70.46% vs. 59.29%, t = 33.954, P < 0.01) and for maximal midexpiratory flow (MMEF, equals to FEF25–75%) was 22% (0.82 vs. 0.67, t = 21.303, P < 0.01). The 1990-North China and 2009-North China equations predicted higher mean values of FEV1/FVC and FEF25–75% than the present model. The biggest degrees of difference were −4% (78.31% vs. 81.27%, t = −85.359, P < 0.01) and −60% (2.11 vs. 4.68, t = −170.287, P < 0.01), respectively.Conclusions:The newly developed spirometric reference equations are applicable to elderly Chinese in Jinan. The 2012-GLI and 2006-Hong Kong equations may lead to missed diagnoses of obstructive ventilatory defects and the small airway dysfunction, while traditional linear equations for all ages may lead to overdiagnosis.

Reference Equations for Spirometry in the Canadian Population.

Spirometry plays a major role in the diagnosis and assessment of severity of lung disease. Determining which lung function values are normal and which are below the lower limit of normal depends on reference equations derived from an appropriate population. The purpose of this study was to derive spirometric reference equations for the Canadian population. The Canadian Health Measures Survey consisted of a respiratory questionnaire, urinary cotinine measurements, and spirometry performed in the sitting position with rigorous quality control standards. Of the 16,606 respondents between 6 and 79 years of age, 11,145 were eliminated for positive responses to the respiratory questionnaire, tobacco exposure, or inability to provide high-quality spirograms. Of the remaining 5,461, roughly half were less than 18 years of age. Quantile regression was used to derive predictive (median) and lower limit of normal equations for males and females for FEV1, FVC, and FEV1/FVC ratio for those with ages greater and less than 18 years. The resulting equations were compared with those from the Global Lung Initiative (GLI) and National Health and Nutrition Examination Survey (NHANES) III by using an ideal subject on the 50th percentile for height and between the ages of 6 and 79 years; the comparison showed minor and inconsistent discrepancies among the predictive equations. A plot of residuals (predicted minus measured value for each subject) suggested a marginally better fit compared with the GLI and NHANES III equations, although differences among the equations were small and unlikely to have any clinical significance. This study provides spirometric reference equations for the Canadian population that were measured under the recommended clinical conditions and with rigorous quality control.

The effect of applying ethnicity-specific spirometric reference equations to Asian migrant workers in Korea.

ObjectivesAsian migrant workers in Korea have various ethnicities. The purpose of this study was to evaluate the difference in spirometric interpretation made using the set of third National Health and Nutrition Examination Survey (NHANES III) reference equations and the relevant ethnicity-specific reference sets.MethodsSpirometry was performed on 166 migrant and 498 Korean male workers between March and November 2012. We analyzed the spirometric data of healthy never-smokers. Spirometric patterns were evaluated using the NHANES III reference set and some relevant ethnicity-specific equations (Eom’s equation for Koreans, Ip’s equation for East Asians, Crapo’s equation for Central Asians, Memon’s equation for South Asians, and Gnanou’s equation for Southeast Asian people).ResultsIn all migrant groups except the Central Asian group, the forced expiratory volume in 1 second percentage (FEV1%) and forced vital capacity percentage (FVC%) calculated using each of the ethnicity-specific reference equations considered were significantly higher than those calculated using the NHANES III reference set. This study showed that in the evaluation of the spirometric result of subjects from Southeast Asia or South Asia, the percentage of cases with an abnormal FEV1 or FVC increased when the NHANES III set of equations was used as compared to when the ethnicity-specific equations were used.ConclusionsWe found that the spirometric results of all ethnic groups were higher and the composition of the abnormal spirometric result was lower when the ethnicity-specific reference equations were used instead of the NHANES III reference set.

A physiologically based model for spirometric reference equations in adults.

A spirometric reference equation consists of a mathematical model with constants and coefficients optimized to fit a specific data set from healthy individuals. Commonly applied models are selected on statistical rather than physiological considerations. A predetermined model with constants and coefficients optimized to various populations would enable interpretable and interesting comparisons between populations. Lubiński and Gólczewski recently presented a piecewise linear model with constants and coefficients claimed to be physiologically interpretable (Lubiński model). Three questions were addressed: Is the Lubiński model as useful clinically as other models: multiple linear, piecewise polynomial and exponential with splines? Will reference equations based on the Lubiński model and optimized to a Swedish and to a Polish population allow for interpretable comparisons? Are three well-known reference equations clinically useful in the Swedish adult population? A recent Swedish random population sample with high-quality spirometric measurements enabled the present analyses. When optimized to fit the Swedish population sample, the Lubiński model and two other models provided accurate predictive normal values. Interesting differences were demonstrated between the Polish and Swedish populations. The proportion of subjects below lower limit normal was adequate for the piecewise polynomial equations but too low and not clinically useful for the advocated exponential equations with splines. It is concluded that the Lubiński model is clinically as useful as other models, and it adds important value and is recommended for future spirometric reference equations for adults. The advocated exponential equations with splines are not recommended for Swedish adults because of too wide normal limits.

Spirometric reference values for healthy Han children aged 5-15 years in Guangzhou, southern China.

Reliable interpretation of spirometry rests on appropriate reference values, but there are few published reference values for healthy children in China. To develop the updated spirometric normative values for healthy children aged 5-15 years in Guangzhou, southern China, and to explore the differences by comparison with published reference values. In this cross-sectional study, health questionnaire and physical examination conducted for screening healthy Han children. Spirometry was performed by well-trained technicians according to American Thoracic Society guidelines. Using Lambda-Mu-Sigma (LMS) algorithm, predicted equations for the median and lower limits of normal were derived for forced vital capacity (FVC), forced expiratory volume in one second (FEV1 ), peak expiratory flow (PEF), and maximal mid-expiratory flow (FEF25-75% ). Predicted values were compared with other published spirometric reference equations. Data were obtained from 422 healthy children (226 boys and 196 girls) aged 5-15 years. Spirometric parameters showed moderate-to-strong positive correlations with age, height, and weight in both genders, with height being the most crucial predictor. There were significant differences between spirometric values and other published reference values. Spirometric values were comparable with the data derived from the same area population in 2002, with exception of increased height and weight in the equivalent age groups. The present spirometric reference equations are feasible for assessment of lung function among children in southern China. Further studies for establishment of reference values for Chinese children in other regions are needed.

Impact of switching to new spirometric reference equations on severity staging of airflow obstruction in COPD: a cross-sectional observational study in primary care

Background:Severity of airflow obstruction in chronic obstructive pulmonary disease (COPD) is based on forced expiratory volume in one second expressed as percentage predicted (FEV1%predicted) derived from reference equations for spirometry results.Aims:To establish how switching to new spirometric reference equations would affect severity staging of airflow obstruction in the Dutch primary care COPD patient population.Methods:Spirometry tests of 3,370 adults aged ≥40 years with obstruction (postbronchodilator FEV1/forced vital capacity (FVC) <0.70) were analysed. The presence and severity of obstruction were defined using Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria. Postbronchodilator FEV1%predicted was calculated using three reference equations: corrected European Community of Steel and Coal (ECSC) (currently recommended in Dutch primary care), Swanney et al., and Global Lung Initiative (GLI). Discordances between severity classifications based on these equations were analysed.Results:We studied 1,297 (38.5%) females and 2,073 males. Application of contemporary reference equations (i.e. Swanney and GLI) changed the GOLD severity stages obtained with the ECSC equations, mostly into milder stages. Severity of airflow obstruction was staged differently in 14.0% and 6.3%, respectively, when the Swanney et al. and GLI reference equations were applied.Conclusions:Compared with the (corrected) ECSC equations, switching to more contemporary reference equations would result in lower FEV1 predicted values and affect interpretation of spirometry by reclassifying 6–14% of primary care COPD patients into different (mostly milder) severity stages. If and how this will affect GPs' treatment choices in individual patients with COPD requires further investigation.

New spirometric reference equations for healthy Chilean adults

To correctly interpret spirometric results, reference values should come from the same population. Current spirometric reference equations have been under scrutiny due to deficiencies to fit adequately for Chilean population, specially, for those aged over 65 years old. To develop new spirometric reference values for Chilean adults, based on national studies in which spirometries were performed in healthy non-smoker adults. A standardized database of spirometric values was developed combining spirometric data collected from five population-based studies, in which healthy nonsmoker adults participated. Spirometries from 448 males aged 19 to 84 years and from 726 females aged 19 to 94 years, obtained according to guidelines from the American Thoracic and European Respiratory Societies, were analyzed. Using multiple regression models, which included height, gender, and age, the theoretical value and inferior limits of normality were calculated for 1st second (FEV1), forced vital capacity (FVC), FEV1/FVC, and forced mid-expiratory flow rate (FEF25-75). Reference values and lower limits of normality (LLN) were constructed for Chilean adults of both genders. The new proposed set of equations had a better fit, when compared with the current reference values used in Chile. The new spirometric references values derived from this study, fit better than currently used ones. Therefore, they should be used as new references values for Chilean adults.

Predicted lower limit of normal reduces misclassification risk of airflow limitation in asymptomatic elderly never-smokers

Background It remains controversial what better defines abnormal lung function at the extremes of age. This study aimed to establish new spirometric reference equations for residents in Jinan and compare the most accepted two spirometric definitions of chronic obstructive pulmonary disease (COPD)—a fixed post-bronchodilator ratio of forced expiratory volume in one second to forced vital capacity (FEV1/FVC) below 70% vs. FEV1/FVC &lt;lower limit of normal (LLN)—in an elderly population (age ≥60 years). Methods Among 10 002 cases, only never-smokers who had no respiratory symptoms or diagnoses of cardiopulmonary diseases and whose lung function measurements strictly followed the American Thoracic Society guidelines, were included in the statistical analysis. For each gender, prediction equations of FEV1, FVC, FEV1 /FVC and corresponding LLN values were developed using multiple regression models. Results In this cross-sectional study, spirometric reference values were statistically derived from a sample of 1328 healthy never-smokers (672 males, 656 females), age 56–84 years. As expected, age and height were the main predictors for all lung function parameters. Using the two spirometric definitions, the number of pulmonary function test results interpreted as obstructed varied markedly in the elderly population for both genders (males: χ2=19.59, P &lt; 0.01; females: χ2=5.67, P=0.017). Conclusions The Global Initiative for Chronic Obstructive Lung Disease (GOLD) criterion probably leads to over-diagnosis in asymptomatic elderly never-smokers. Our study suggests that the predicted LLN values will reduce the misclassification risk instead. However, cohort studies are urgently needed for clinical validation.