Race/Ethnicity, Spirometry Reference Equations, and Prediction of Incident Clinical Events: The Multi-Ethnic Study of Atherosclerosis (MESA) Lung Study.

Rationale: Normal values for FEV1 and FVC are currently calculated using cross-sectional reference equations that include terms for race/ethnicity, an approach that may reinforce disparities and is of unclear clinical benefit. Objectives: To determine whether race/ethnicity-based spirometry reference equations improve the prediction of incident chronic lower respiratory disease (CLRD) events and mortality compared with race/ethnicity-neutral equations. Methods: The MESA Lung Study, a population-based, prospective cohort study of White, Black, Hispanic, and Asian adults, performed standardized spirometry from 2004 to 2006. Predicted values for spirometry were calculated using race/ethnicity-based equations following guidelines and, alternatively, race/ethnicity-neutral equations without terms for race/ethnicity. Participants were followed for events through 2019. Measurements and Main Results: The mean age of 3,344 participants was 65 years, and self-reported race/ethnicity was 36% White, 25% Black, 23% Hispanic, and 17% Asian. There were 181 incident CLRD-related events and 547 deaths over a median of 11.6 years. There was no evidence that percentage predicted FEV1 or FVC calculated using race/ethnicity-based equations improved the prediction of CLRD-related events compared with those calculated using race/ethnicity-neutral equations (difference in C statistics for FEV1, -0.005; 95% confidence interval [CI], -0.013 to 0.003; difference in C statistic for FVC, -0.008; 95% CI, -0.016 to -0.0006). Findings were similar for mortality (difference in C statistics for FEV1, -0.002; 95% CI, -0.008 to 0.003; difference in C statistics for FVC, -0.004; 95% CI, -0.009 to 0.001). Conclusions: There was no evidence that race/ethnicity-based spirometry reference equations improved the prediction of clinical events compared with race/ethnicity-neutral equations. The inclusion of race/ethnicity in spirometry reference equations should be reconsidered.

Interaction between Genetic Risk Scores for reduced pulmonary function and smoking, asthma and endotoxin.

RATIONALE: Genome-wide association studies (GWASs) have identified numerous loci associated with lower pulmonary function. Pulmonary function is strongly related to smoking and has also been associated with asthma and dust endotoxin. At the individual SNP level, genome-wide analyses of pulmonary function have not identified appreciable evidence for gene by environment interactions. Genetic Risk Scores (GRSs) may enhance power to identify gene-environment interactions, but studies are few. METHODS: We analysed 2844 individuals of European ancestry with 1000 Genomes imputed GWAS data from a case-control study of adult asthma nested within a US agricultural cohort. Pulmonary function traits were FEV1, FVC and FEV1/FVC. Using data from a recent large meta-analysis of GWAS, we constructed a weighted GRS for each trait by combining the top (p value<5×10-9) genetic variants, after clumping based on distance (±250 kb) and linkage disequilibrium (r2=0.5). We used linear regression, adjusting for relevant covariates, to estimate associations of each trait with its GRS and to assess interactions. RESULTS: Each trait was highly significantly associated with its GRS (all three p values<8.9×10-8). The inverse association of the GRS with FEV1/FVC was stronger for current smokers (pinteraction=0.017) or former smokers (pinteraction=0.064) when compared with never smokers and among asthmatics compared with non-asthmatics (pinteraction=0.053). No significant interactions were observed between any GRS and house dust endotoxin. CONCLUSIONS: Evaluation of interactions using GRSs supports a greater impact of increased genetic susceptibility on reduced pulmonary function in the presence of smoking or asthma.

Raw milk consumption and other early-life farm exposures and adult pulmonary function in the Agricultural Lung Health Study.

Literature suggests that early exposure to the farming environment protects against atopy and asthma; few studies have examined pulmonary function. We evaluated associations between early-life farming exposures and pulmonary function in 3061 adults (mean age=63) from a US farming population using linear regression. Childhood raw milk consumption was associated with higher FEV1 (ß=49.5 mL, 95% CI 2.8 to 96.1 mL, p=0.04) and FVC (ß=66.2 mL, 95% CI 13.2 to 119.1 mL, p=0.01). We did not find appreciable associations with other early-life farming exposures. We report a novel association between raw milk consumption and higher pulmonary function that lasts into older adulthood.

Recommendations for a Standardized Pulmonary Function Report. An Official American Thoracic Society Technical Statement.

BACKGROUND: The American Thoracic Society committee on Proficiency Standards for Pulmonary Function Laboratories has recognized the need for a standardized reporting format for pulmonary function tests. Although prior documents have offered guidance on the reporting of test data, there is considerable variability in how these results are presented to end users, leading to potential confusion and miscommunication. METHODS: A project task force, consisting of the committee as a whole, was approved to develop a new Technical Standard on reporting pulmonary function test results. Three working groups addressed the presentation format, the reference data supporting interpretation of results, and a system for grading quality of test efforts. Each group reviewed relevant literature and wrote drafts that were merged into the final document. RESULTS: This document presents a reporting format in test-specific units for spirometry, lung volumes, and diffusing capacity that can be assembled into a report appropriate for a laboratory's practice. Recommended reference sources are updated with data for spirometry and diffusing capacity published since prior documents. A grading system is presented to encourage uniformity in the important function of test quality assessment. CONCLUSIONS: The committee believes that wide adoption of these formats and their underlying principles by equipment manufacturers and pulmonary function laboratories can improve the interpretation, communication, and understanding of test results.

Use of forced vital capacity and forced expiratory volume in 1 second quality criteria for determining a valid test.

The 2005 American Thoracic Society (ATS)/European Respiratory Society (ERS) spirometry guidelines define valid tests as having three acceptable blows and a repeatable forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1). The aim of this study was to determine how reviewer and computer-determined ATS/ERS quality could affect population reference values for FVC and FEV1. Spirometry results from 7777 normal subjects aged 8-80 years (NHANES (National Health and Nutrition Examination Survey) III) were assigned quality grades A to F for FVC and FEV1 by a computer and one reviewer (reviewer 1). Results from a subgroup of 1466 Caucasian adults (aged 19-80 years ) were reviewed by two additional reviewers. Mean deviations from NHANES III predicted for FVC and FEV1 were examined by quality grade (A to F). Reviewer 1 rejected (D and F grade) 5.2% of the 7777 test sessions and the computer rejected ∼16%, primarily due to end-of-test (EOT) failures. Within the subgroup, the computer rejected 11.5% of the results and the three reviewers rejected 3.7-5.9%. Average FEV1 and FVC were minimally influenced by grades A to C allocated by reviewer 1. Quality assessment of individual blows including EOT assessments should primarily be used as an aid to good quality during testing rather than for subsequently disregarding data. Reconsideration of EOT criteria and its application, and improved grading standards and training in over-reading are required. Present EOT criteria results in the exclusion of too many subjects while having minimal impact on predicted values.

Official American Thoracic Society technical standards: spirometry in the occupational setting.

PURPOSE: This document addresses aspects of the performance and interpretation of spirometry that are particularly important in the workplace, where inhalation exposures can affect lung function and cause or exacerbate lung diseases, such as asthma, chronic obstructive pulmonary disease, or fibrosis. METHODS: Issues that previous American Thoracic Society spirometry statements did not adequately address with respect to the workplace were identified for systematic review. Medline 1950-2012 and Embase 1980-2012 were searched for evidence related to the following: training for spirometry technicians; testing posture; appropriate reference values to use for Asians in North America; and interpretative strategies for analyzing longitudinal change in lung function. The evidence was reviewed and technical recommendations were developed. RESULTS: Spirometry performed in the work setting should be part of a comprehensive workplace respiratory health program. Effective technician training and feedback can improve the quality of spirometry testing. Posture-related changes in FEV1 and FVC, although small, may impact interpretation, so testing posture should be kept consistent and documented on repeat testing. Until North American Asian-specific equations are developed, applying a correction factor of 0.88 to white reference values is considered reasonable when testing Asian American individuals in North America. Current spirometry should be compared with previous tests. Excessive loss in FEV1 over time should be evaluated using either a percentage decline (15% plus loss expected due to aging) or one of the other approaches discussed, taking into consideration testing variability, worker exposures, symptoms, and other clinical information. CONCLUSIONS: Important aspects of workplace spirometry are discussed and recommendations are provided for the performance and interpretation of workplace spirometry.

Occupational risk factors for COPD phenotypes in the Multi-Ethnic Study of Atherosclerosis (MESA) Lung Study.

INTRODUCTION: The contribution of occupational exposure to the risk of chronic obstructive pulmonary disease COPD in population-based studies is of interest. We compared the performance of self-reported exposure to a newly developed JEM in exposure-response evaluation. METHODS: We used cross-sectional data from Multi-Ethnic Study of Atherosclerosis (MESA), a population-based sample of 45-84 year olds free of clinical cardiovascular disease at baseline. MESA ascertained the most recent job and employment, and the MESA Lung Study measured spirometry, and occupational exposures for 3686 participants. Associations between health outcomes (spirometry defined airflow limitation and Medical Research Council-defined chronic bronchitis) and occupational exposure [self-reported occupational exposure to vapor-gas, dust, or fumes (VGDF), severity of exposure, and a job-exposure matrix (JEM)-derived score] were evaluated using logistic regression models adjusted for non-occupational risk factors. RESULTS: The prevalence of airflow limitation was associated with self-reported exposure to vapor-gas (OR 2.6, 95%CI 1.1-2.3), severity of VGDF exposure (P-trend < 0.01), and JEM dust exposure (OR 2.4, 95%CI 1.1-5.0), and with organic dust exposure in females; these associations were generally of greater magnitude among never smokers. The prevalence of chronic bronchitis and wheeze was associated with exposure to VGDF. The association between airflow limitation and the combined effect of smoking and VGDF exposure showed an increasing trend. Self-reported vapor-gas, dust, fumes, years and severity of exposure were associated with increased prevalence of chronic bronchitis and wheeze (P < 0.001). CONCLUSIONS: Airflow limitation was associated with self-reported VGDF exposure, its severity, and JEM-ascertained dust exposure in smokers and never-smokers in this multiethnic study.

Multi-ethnic reference values for spirometry for the 3-95-yr age range: the global lung function 2012 equations.

The aim of the Task Force was to derive continuous prediction equations and their lower limits of normal for spirometric indices, which are applicable globally. Over 160,000 data points from 72 centres in 33 countries were shared with the European Respiratory Society Global Lung Function Initiative. Eliminating data that could not be used (mostly missing ethnic group, some outliers) left 97,759 records of healthy nonsmokers (55.3% females) aged 2.5-95 yrs. Lung function data were collated and prediction equations derived using the LMS method, which allows simultaneous modelling of the mean (mu), the coefficient of variation (sigma) and skewness (lambda) of a distribution family. After discarding 23,572 records, mostly because they could not be combined with other ethnic or geographic groups, reference equations were derived for healthy individuals aged 3-95 yrs for Caucasians (n=57,395), African-Americans (n=3,545), and North (n=4,992) and South East Asians (n=8,255). Forced expiratory value in 1 s (FEV(1)) and forced vital capacity (FVC) between ethnic groups differed proportionally from that in Caucasians, such that FEV(1)/FVC remained virtually independent of ethnic group. For individuals not represented by these four groups, or of mixed ethnic origins, a composite equation taken as the average of the above equations is provided to facilitate interpretation until a more appropriate solution is developed. Spirometric prediction equations for the 3-95-age range are now available that include appropriate age-dependent lower limits of normal. They can be applied globally to different ethnic groups. Additional data from the Indian subcontinent and Arabic, Polynesian and Latin American countries, as well as Africa will further improve these equations in the future.

Residential Wood Burning and Pulmonary Function in the Agricultural Lung Health Study.

BACKGROUND: In low- and middle-income countries, burning biomass indoors for cooking or heating has been associated with poorer lung function. In high-income countries, wood, a form of biomass, is commonly used for heating in rural areas with increasing prevalence. However, in these settings the potential impact of chronic indoor woodsmoke exposure on pulmonary function is little studied. OBJECTIVE: We evaluated the association of residential wood burning with pulmonary function in case-control study of asthma nested within a U.S. rural cohort. METHODS: Using sample weighted multivariable linear regression, we estimated associations between some and frequent wood burning, both relative to no exposure, in relation to forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), their ratio (FEV1/FVC), and fractional exhaled nitric oxide (FeNO). We examined effect modification by smoking or asthma status. RESULTS: Among all participants and within smoking groups, wood burning was not appreciably related to pulmonary function. However, in individuals with asthma (n=1,083), frequent wood burning was significantly associated with lower FEV1 [ß: -164mL; 95% confidence interval (CI): -261, -66mL], FVC (ß: -125mL; 95% CI: -230, -20mL), and FEV1/FVC (ß: -2%; 95% CI: -4, -0.4%), whereas no appreciable association was seen in individuals without asthma (n=1,732). These differences in association by asthma were statistically significant for FEV1 (pinteraction=0.0044) and FEV1/FVC (pinteraction=0.049). Frequent wood burning was also associated with higher FeNO levels in all individuals (n=2,598; ß: 0.1 ln(ppb); 95% CI: 0.02, 0.2), but associations did not differ by asthma or smoking status. DISCUSSION: Frequent exposure to residential wood burning was associated with a measure of airway inflammation (FeNO) among all individuals and with lower pulmonary function among individuals with asthma. This group may wish to reduce wood burning or consider using air filtration devices. https://doi.org/10.1289/EHP10734.

Similar relation of age and height to lung function among Whites, African Americans, and Hispanics.

Current guidelines recommend separate spirometry reference equations for whites, African Americans, and Mexican Americans, but the justification for this recommendation is controversial. The authors examined the statistical justification for race/ethnic-specific reference equations in adults in the Third National Health and Nutrition Examination Survey (1988-1994) and the Multi-Ethnic Study of Atherosclerosis Lung Study (2000-2006). Spirometry was measured following American Thoracic Society guidelines. "Statistical justification" was defined as the presence of effect modification by race/ethnicity among never-smoking participants without respiratory disease or symptoms and was tested with interaction terms for race/ethnicity (× age and height) in regression models. There was no evidence of effect modification by race/ethnicity for forced expiratory volume in 1 second, forced vital capacity, or the forced expiratory volume in 1 second/forced vital capacity ratio among white, African-American, and Mexican-American men or women on an additive scale or a log scale. Interaction terms for race/ethnicity explained less than 1% of variability in lung function. The mean lung function for a given age, gender, and height was the same for whites and Mexican Americans but was lower for African Americans. Findings were similar in the Multi-Ethnic Study of Atherosclerosis Lung Study. The associations of age and height with lung function are similar across the 3 major US race/ethnic groups. Multiethnic rather than race/ethnic-specific spirometry reference equations are applicable for the US population.

Spirometry centile charts for young Caucasian children: the Asthma UK Collaborative Initiative.

RATIONALE: Advances in spirometry measurement techniques have made it possible to obtain measurements in children as young as 3 years of age; however, in practice, application remains limited by the lack of appropriate reference data for young children, which are often based on limited population-specific samples. OBJECTIVES: We aimed to build on previous models by collating existing reference data in young children (aged 3-7 yr), to produce updated prediction equations that span the preschool years and that are also linked to established reference equations for older children and adults. METHODS: The Asthma UK Collaborative Initiative was established to collate lung function data from healthy young children aged 3 to 7 years. Collaborators included researchers with access to pulmonary function test data in healthy preschool children. Spirometry centiles were created using the LMS (lambda, micro, sigma) method and extend previously published equations down to 3 years of age. MEASUREMENTS AND MAIN RESULTS: The Asthma UK centile charts for spirometry are based on the largest sample of healthy young Caucasian children aged 3-7 years (n = 3,777) from 15 centers across 11 countries and provide a continuous reference with a smooth transition into adolescence and adulthood. These equations improve existing pediatric equations by considering the between-subject variability to define a more appropriate age-dependent lower limit of normal. The collated data set reflects a variety of equipment, measurement protocols, and population characteristics and may be generalizable across different populations. CONCLUSIONS: We present prediction equations for spirometry for preschool children and provide a foundation that will facilitate continued updating.

Cross-sectional and longitudinal spirometry in children and adolescents: interpretative strategies.

RATIONALE: Single and serial spirometric data are commonly compared with predicted values to assess pulmonary function and normal lung growth. OBJECTIVES: Do reference equations adequately describe pulmonary function in a population and in growing individuals? METHODS: We applied five sets of reference equations with appropriate age ranges to cross-sectional data of FEV(1), FVC, and FEV(1)/FVC from the United States, Estonia, and The Netherlands (1,487 boys and 1,340 girls, 6 to 18 years of age), and to serial measurements in Dutch (430 girls and 769 boys, 6 to 19 years of age) and in German and Austrian children (1,305 girls and 1,303 boys, 6 to 13 years of age). MEASUREMENTS AND MAIN RESULTS: Compared with reference equations from Polgar and Zapletal, cross-sectional FEV(1) and FVC declined between the ages of 6 and 12 and then increased, leading to a spurious change of up to 25% predicted; this pattern was most pronounced in boys. In cross-sectional data this trend was much weaker when using reference equations from Hankinson, Quanjer, and Stanojevic, and these equations provided a good fit from the age of 12 upward. In longitudinal data (i.e., within individuals), the trend was more pronounced for FEV(1) in boys than in girls. No set of equations provided a satisfactory fit in the lower limits of normal, but Hankinson and Stanojevic equations performed best. CONCLUSIONS: Spirometric reference equations that use only height for predicting pulmonary function are unsuitable for describing the progression of pulmonary function. Those that incorporate height and age demonstrate some discrepancy with longitudinal data. Failure to take these spurious trends into account leads to significant errors in estimating the natural course of respiratory disease, in allocating patients to treatment groups, or in assessing long-term effects of drug intervention in school children and adolescents.

House Dust Endotoxin Levels Are Associated with Adult Asthma in a U.S. Farming Population.

RATIONALE: Endotoxin initiates a proinflammatory response from the innate immune system. Studies in children suggest that endotoxin exposure from house dust may be an important risk factor for asthma, but few studies have been conducted in adult populations. OBJECTIVES: To investigate the association of house dust endotoxin levels with asthma and related phenotypes (wheeze, atopy, and pulmonary function) in a large U.S. farming population. METHODS: Dust was collected from the bedrooms (n = 2,485) of participants enrolled in a case-control study of current asthma (927 cases) nested within the Agricultural Health Study. Dust endotoxin was measured by Limulus amebocyte lysate assay. Outcomes were measured by questionnaire, spirometry, and blood draw. We evaluated associations using linear and logistic regression. MEASUREMENTS AND MAIN RESULTS: Endotoxin was significantly associated with current asthma (odds ratio [OR], 1.30; 95% confidence interval [CI], 1.14-1.47), and this relationship was modified by early-life farm exposure (born on a farm: OR, 1.18; 95% CI, 1.02-1.37; not born on a farm: OR, 1.67; 95% CI, 1.26-2.20; Interaction P = 0.05). Significant positive associations were seen with both atopic and nonatopic asthma. Endotoxin was not related to either atopy or wheeze. Higher endotoxin was related to lower FEV1/FVC in asthma cases only (Interaction P = 0.01). For asthma, there was suggestive evidence of a gene-by-environment interaction for the CD14 variant rs2569190 (Interaction P = 0.16) but not for the TLR4 variants rs4986790 and rs4986791. CONCLUSIONS: House dust endotoxin was associated with current atopic and nonatopic asthma in a U.S. farming population. The degree of the association with asthma depended on early-life farm exposures. Furthermore, endotoxin was associated with lower pulmonary function in patients with asthma.

Reference Equations for Spirometry in the Canadian Population.

RATIONALE: 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. OBJECTIVES: The purpose of this study was to derive spirometric reference equations for the Canadian population. METHODS: 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. MEASUREMENTS AND MAIN RESULTS: 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. CONCLUSIONS: This study provides spirometric reference equations for the Canadian population that were measured under the recommended clinical conditions and with rigorous quality control.

Lung VITAL: Rationale, design, and baseline characteristics of an ancillary study evaluating the effects of vitamin D and/or marine omega-3 fatty acid supplements on acute exacerbations of chronic respiratory disease, asthma control, pneumonia and lung function in adults.

Laboratory and observational research studies suggest that vitamin D and marine omega-3 fatty acids may reduce risk for pneumonia, acute exacerbations of respiratory diseases including chronic obstructive lung disease (COPD) or asthma, and decline of lung function, but prevention trials with adequate dosing, adequate power, and adequate time to follow-up are lacking. The ongoing Lung VITAL study is taking advantage of a large clinical trial-the VITamin D and OmegA-3 TriaL (VITAL)--to conduct the first major evaluation of the influences of vitamin D and marine omega-3 fatty acid supplementation on pneumonia risk, respiratory exacerbation episodes, asthma control and lung function in adults. VITAL is a 5-year U.S.-wide randomized, double-blind, placebo-controlled, 2 × 2 factorial trial of supplementation with vitamin D3 ([cholecalciferol], 2000 IU/day) and marine omega-3 FA (Omacor® fish oil, eicosapentaenoic acid [EPA]+docosahexaenoic acid [DHA], 1g/day) for primary prevention of CVD and cancer among men and women, at baseline aged ≥50 and ≥55, respectively, with 5107 African Americans. In a subset of 1973 participants from 11 urban U.S. centers, lung function is measured before and two years after randomization. Yearly follow-up questionnaires assess incident pneumonia in the entire randomized population, and exacerbations of respiratory disease, asthma control and dyspnea in a subpopulation of 4314 randomized participants enriched, as shown in presentation of baseline characteristics, for respiratory disease, respiratory symptoms, and history of cigarette smoking. Self-reported pneumonia hospitalization will be confirmed by medical record review, and exacerbations will be confirmed by Center for Medicare and Medicaid Services data review.

Lung function decline over 25 years of follow-up among black and white adults in the ARIC study cohort.

BACKGROUND: Interpretation of longitudinal information about lung function decline from middle to older age has been limited by loss to follow-up that may be correlated with baseline lung function or the rate of decline. We conducted these analyses to estimate age-related decline in lung function across groups of race, sex, and smoking status while accounting for dropout from the Atherosclerosis Risk in Communities Study. METHODS: We analyzed data from 13,896 black and white participants, aged 45-64 years at the 1987-1989 baseline clinical examination. Using spirometry data collected at baseline and two follow-up visits, we estimated annual population-averaged mean changes in forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) by race, sex, and smoking status using inverse-probability-weighted independence estimating equations conditioning-on-being-alive. RESULTS: Estimated rates of FEV1 decline estimated using inverse-probability-weighted independence estimating equations conditioning on being alive were higher among white than black participants at age 45 years (e.g., male never smokers: black: -29.5 ml/year; white: -51.9 ml/year), but higher among black than white participants by age 75 (black: -51.2 ml/year; white: -26). Observed differences by race were more pronounced among men than among women. By smoking status, FEV1 declines were larger among current than former or never smokers at age 45 across all categories of race and sex. By age 60, FEV1 decline was larger among former and never than current smokers. Estimated annual declines generated using unweighted generalized estimating equations were smaller for current smokers at younger ages in all four groups of race and sex compared with results from weighted analyses that accounted for attrition. CONCLUSIONS: Using methods accounting for dropout from an approximately 25-year health study, estimated rates of lung function decline varied by age, race, sex, and smoking status, with largest declines observed among current smokers at younger ages.

Spirometric reference values for the 6-s FVC maneuver.

STUDY OBJECTIVES: The guidelines of the National Lung Health Education Program for COPD screening proposed a shorter FVC maneuver (forced expiratory volume at 6 s of exhalation [FEV(6)]). Although reference values for FEV(6) are available from the third National Health and Nutrition Examination Survey, forced expiratory flow between 25% and 75% of FVC (FEF(25-75%)) reference values for the shorter 6-s maneuver are not available and are needed. In particular, calculation of largest observed volume during the first 6 s of an FVC maneuver (FVC(6)), from a shortened FVC maneuver, is necessary because the FEF(25-75%) measurement is based on a percentage of FVC or, for a shorter maneuver, FVC(6). DESIGN: We reanalyzed the raw volume-time curves from the third National Health and Nutrition Examination Survey to calculate FVC(6), forced expiratory volume at 0.5 s of exhalation, forced expiratory volume at 3 s of exhalation, ratio of the FEV(1) to largest observed volume during the first 6 s of an FVC maneuver expressed as a percentage (FEV(1)/FEV(6)%), and forced expiratory flow between 25% and 75% of the largest observed volume during the first 6 s of an FVC maneuver (FEF(25-75%6)) in addition to the previously reported values for FEV(1), FEV(6), and FEV(1)/FEV(6)%. PATIENTS OR PARTICIPANTS: Using the same normal, asymptomatic, nonsmoking reference population from a previous study, reference values for these parameters were derived from best values. RESULTS: A total of 2,261 white, 2,564 African-American, and 2,666 Mexican-American subjects aged 8 to 80 years were included in the analysis. Fifty-four subjects from the previous study were not included due to missing raw volume-time curves. CONCLUSIONS: These reference values, utilizing the FVC(6), provide investigators with the means of evaluating the relative merits of using the shorter FVC maneuver as a surrogate for the traditional FVC. They are needed particularly for calculating FEF(25-75%), as statistically significant differences were observed between the FEF(25-75%) and FEF(25-75%6).

Is my lung function really that good? Flow-type spirometer problems that elevate test results.

Most spirometry errors reduce test results, and it is widely assumed that measurement accuracy is guaranteed by frequent spirometer calibrations or calibration checks. However, zero errors and changes in flow-type spirometer sensors may occur during testing that significantly elevate test results, even though the spirometer was calibrated recently. To draw attention to these often-unrecognized problems, this report presents anomalous spirograms and test results obtained from occupational medicine clinics and hospital pulmonary function laboratories during quality assurance spirogram reviews. The spurious results appear to have been caused by inaccurate zeroing of the flow sensor, or by condensation, mucus deposition, or unstable calibration of various flow-type spirometers. These errors elevated some FVCs to 144 to 204% of predicted and probably caused 40% of 121 middle-aged working men in respirator medical clearance programs to record both FVC and FEV1 > 120% of predicted. Since spirometers report the largest values from a test, these errors must be recognized and deleted to avoid false-negative interpretations. Flow-type spirometer users at all levels, from the technician to the interpreter of test results, should be aware of the potential for and the appearance of these errors in spirograms.