New Danish reference values for spirometry

Introduction: 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. Objectives: 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. Methods: 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. Results: 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. Conclusion: 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. Please cite this paper as: Løkke A, Marott JL, Mortensen J, Nordestgaard BG, Dahl M and Lange P. New Danish reference values for spirometry. Clin Respir J 2013; 7: 153–167.     

Forced spirometry reference values for Norwegian adults: the Bronchial Obstruction in Nord-Tr?ndelag Study.

The purpose of this study was to develop new prediction equations for flow/volume spirometry parameters in asymptomatic, never-smoking adults in Norway, and to assess any differences of these parameters when applying the new and most commonly used equation sets. Flow/volume spirometry was measured according to the American Thoracic Society criteria in 2,792 subjects aged > or = 20 yrs, randomly selected from participants in the Nord-Tr?ndelag Health Study. Ever-smokers and subjects with respiratory symptoms and/or diseases reported in this questionnaire were excluded. A total of 546 females and 362 males met the inclusion criteria and were included in the analyses. Most lung function variables were nonlinear by age and had to be transformed. After a plateau in younger adults, the variables declined by age. The reference values for forced expiratory volume in one second and forced vital capacity from the present study, were higher than those given by prediction equations from the European Community for Coal and Steel, but in closer agreement with later studies from Europe, Australia and the USA. Healthcare providers should be encouraged to reconsider their choice of prediction equations of spirometry in order to improve management of obstructive lung diseases.     

Reproducibility of spirometry in Mexican workers and international reference values

OBJECTIVE: To describe spirometric function and adjustment to foreign prediction equations in Mexican workers claiming work related disability. MATERIAL AND METHODS: We reviewed 5771 spirometries done at the Mexican National Institute of Respiratory Diseases performed with equipment and methods proposed by the American Thoracic Society. With the spirometries we generated multiple regression equations separated for men and women based on age and height, compared to other in common use reported by Knudson and Hankinson in North America and by Quanjer in europeans. RESULTS: 80% of the tests were reproducible for FVC and FEV1 according to ATS, whereas 10% were reproducible for neither. Mean FVC in men was 12% above values reported by Quanjer, 22% above Knudson, 3% above Hankinson and 6% above Rodriguez-Reynaga, whereas similar values for women were 18%, 10%, 0% and 1%. Excluding obese and those who had less than 2 acceptable maneuvers, the numbers increase by 1-2%. FEV1 was also above predicted. CONCLUSIONS: Most workers requesting disability are able to generate a reproducible spirometry. However for the same gender, age and height, workers had a FEV1 and a FVC above normal values reported by Knudson and Quanjer and are more similar to those reported by Hankinson in Mexican-Americans. While a set of appropriate reference values are obtained, regression equations obtained from the studied group will generate less error in the evaluation of disability in mexican workers. The English version of this paper is available at: http://www.insp.mx/salud/index.html.     

The Global Lung Initiative 2012 reference values reflect contemporary Australasian spirometry

We aimed to ascertain the fit of the European Respiratory Society Global Lung Initiative 2012 reference ranges to contemporary Australasian spirometric data. Z‐scores for spirometry from Caucasian subjects aged 4–80 years were calculated. The mean (SD) Z‐scores were 0.23 (1.00) for forced expirtory volume in 1 s (FEV₁), 0.23 (1.00) for forced vital capacity (FVC), ?0.03 (0.87) for FEV₁/FVC and 0.07 (0.95) for forced expiratory flows between 25% and 75% of FVC. These results support the use of the Global Lung Initiative 2012 reference ranges to interpret spirometry in Caucasian Australasians.     

Spirometric reference values in Senegalese black adults

Spirometric volumes and expiratory flows were measured among 448 Senegalese males and females of 25-80 yrs of age. The values obtained are similar to those reported for black Africans and black Americans in the literature. Volumes are 15-25% lower in males and 23% lower in females than in Caucasians. Forced expiratory flow between 25-75% of vital capacity (VC), (FEF25-75) is 5-18% lower in males and 19% lower in females. FEF25-75/VC ratio is higher in blacks than in Whites, but the forced expiratory volume in one second FEV1/VC ratio is similar in black and white subjects. However, we cannot use proportional factors to determine spirometric black standards from white reference values, so, equations of regression and nomograms with age and height are proposed for black Africans.     

Laboratory reference values for healthy adults from southern Tanzania

Objectives To define and discuss reference ranges for commonly determined laboratory parameters in healthy adults from southern Tanzania. Methods A population‐based sample of adult volunteers from Mbeya, Tanzania, who were not HIV positive or showing signs and symptoms of other diseases, participated in this study. We enrolled 145 women and 156 men between 19 and 48 years of age to determine clinical chemistry (CC), haematology and lymphocyte immunophenotyping (LIP) parameters using standard laboratory methods. Medians and nonparametric 95% reference ranges for each parameter were determined and compared with reference ranges from the USA, Europe and from other African countries. Results Agreement with ranges from developed countries was poor: for CC values the average concordance was 80.9% and 86.7% with values from two developed countries. Haematology ranges from the USA classified 86.3% of values correctly, whereas ranges from three different sub‐Saharan Africa (SSA) sites classified between 82.5% and 94.5% of values correctly. The agreement of LIP reference ranges was 87.5% with values determined in Germany but between 91.7% and 95.8% compared with values determined at other sites in SSA. Conclusion Clinical reference ranges determined in developed countries are inadequate for use in SSA. Laboratories in this region should either define their own or use values determined under similar conditions. The ranges reported here are more appropriate for use in SSA than ranges determined in developed countries.     

Reference values for spirometry,including vital capacity,in Japanese adults calculated with the LMS method and compared with previous values

BackgroundReference values for lung function tests should be periodically updated because of birth cohort effects and improved technology. This study updates the spirometric reference values, including vital capacity (VC), for Japanese adults and compares the new reference values with previous Japanese reference values.MethodsSpirometric data from healthy non-smokers (20,341 individuals aged 17–95 years, 67% females) were collected from 12 centers across Japan, and reference equations were derived using the LMS method. This method incorporates modeling skewness (lambda: L), mean (mu: M), and coefficient of variation (sigma: S), which are functions of sex, age, and height. In addition, the age-specific lower limits of normal (LLN) were calculated.ResultsSpirometric reference values for the 17–95-year age range and the age-dependent LLN for Japanese adults were derived. The new reference values for FEV₁ in males are smaller, while those for VC and FVC in middle age and elderly males and those for FEV₁, VC, and FVC in females are larger than the previous values. The LLN of the FEV₁/FVC for females is larger than previous values. The FVC is significantly smaller than the VC in the elderly.ConclusionsThe new reference values faithfully reflect spirometric indices and provide an age-specific LLN for the 17–95-year age range, enabling improved diagnostic accuracy. Compared with previous prediction equations, they more accurately reflect the transition in pulmonary function during young adulthood. In elderly subjects, the FVC reference values are not interchangeable with the VC values.     

Effects of changing reference values and definition of the normal range on interpretation of spirometry

Background and objective: Recent spirometry reference studies are arguably the most valid ever performed and the ATS/ERS now recommend the National Health and Nutrition Assessment Survey (NHANES) equations for North America. It is timely to consider adopting these reference values in Australasia; however, an evaluation of the consequences of such a change is required. Methods: We analysed data from 1108 patients tested in two pulmonary function laboratories in public hospitals. Lower limits of normal (LLN) were calculated using European Community for Steel and Coal (ECSC) (1993), Knudson (1983), NHANES (1999) and Health Survey of England (HSE) (2004) equations and used to define restriction (FVC < LLN) and obstruction (FEV₁/FVC < LLN). This interpretative strategy was also compared with the GOLD definition of obstruction (FEV₁/FVC < 70%). Results: Average age for all patients (50% female) was 60 years (range: 20–91). The mean predicted FVC from NHANES and HSE were similar and consistently higher than those from ECSC and Knudson (average 270 mLs). This translates into a 76% increase in the incidence of ‘restrictive’ interpretations using NHANES data compared with ECSC and Knudson, and a smaller increase of 40% for HSE. Using FEV₁/FVC < 70% to diagnose obstruction in those over 65 years would result in false positive rates of approximately 28%. Using the same definition in a younger group (<50 years old) results in a false negative rate of approximately 14%. Conclusions: Changing to either NHANES or HSE predicted values will significantly increase the rate of ‘restrictive’ interpretation, and alter the rate of obstructive findings. The NHANES and HSE data confirm that using FEV₁/FVC < 70% to define obstruction causes misdiagnosis in elderly and younger subjects.     

Assessment of respiratory function: influence of spirometry reference values and normality criteria selection.

The purpose of this study was to determine the impact upon classification of patients of the choice of reference equation and the criterion defining the lower limit of the normal range in clinical practice. One thousand consecutive spirometries were checked to calculate the predicted values [forced vital capacity (FVC) and forced expiratory volume in sec (FEV1)] in accordance with the equations by Morris, Cherniack, Crapo, Knudson and the Economic Community for Coal and Steel (ECCS). We quantified the difference between the predicted values obtained for each individual and each equation, determined the percentage of individuals whose classification might have changed from normal to abnormal when using a different equation and defined the lower limit of the normal range in accordance with the determination of 1. the 90% confidence interval or 2. 80% of predicted, comparing their differences. The greatest differences found were between the values given by Morris and Crapo's equations for male FEV1, between Morris and Cherniak for female FEV1 and male FVC and between Morris and Knudson for female FVC. Using 80% of predicted value for female FEV1, up to 35% of tests changed their classification from 'normal' to 'abnormal' upon changing the equation used. A high percentage of tests showed a lower limit of normal defined by the confidence interval under 80% and 70% of predicted value. This study emphasizes the importance of choosing the appropriate reference equation. We do not consider it acceptable to use a fixed percentage of the predicted value as the lower limit of normal because of the great number of patients found to be inappropriately classified.     

Static lung volumes and airway resistance reference values in healthy adults

Background and objective: The assessment of static lung volumes and airway resistance is a frequently performed diagnostic procedure and considered as an important tool in medical surveillance to detect pulmonary diseases. The objectives of the study are to establish reference equations for body plethysmographic parameters in a representative adult population across a wide age range and to compare the normative values from this sample with previous ones. Methods: Body plethysmography was applied in 1809 participants (885 males) of a cross‐sectional, population‐based survey (Study of Health in Pomerania). Individuals with cardiopulmonary disorders and/or a pack‐year smoking history >10 years and participants with a body mass index >30 kg/m² were excluded. In total, 686 healthy individuals (275 males) aged 25–85 years were assessed. Results: Prediction equations for both genders were established by quantile regression analysis taking into account the influence of age, height and weight. Conclusions: The study provides a novel set of prediction equations for static lung volumes and airway resistance obtained using body plethysmography. Compared with our findings, existing equations underestimated some normal values. The results emphasize the need for up‐to‐date reference equations.     

Differences in spirometry reference values: a statistical comparison of a Mongolian and a Caucasian study.

New reference value studies for spirometry are commonly compared to existing reference value studies using average data derived from existing reference equations. Such comparisons are inherently flawed because they do not account for differences in distributions of the independent and dependent variables and they do not have identical methodologies. This study was undertaken 1) to derive reference equations for forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) for natives of Mongolia and 2) to compare the Mongolian data with data from a 1981 reference study of Caucasians in Salt Lake City, UT, USA. Spirometry was performed on 344 (176 male, 168 female) healthy, nonsmoking urban natives of Mongolia to generate reference equations for FVC, FEV1, and FEV1/FVC. These data were compared with data from a 1981 reference study of Caucasians in Salt Lake City, using both an analysis of covariance of the raw data and parametric and nonparametric comparisons of a matched pair subset. Average measured forced vital capacity and forced expiratory volume in one second in native Mongolians were within 1-2% of the Caucasian predicted values. These small differences are not statistically significant in any of the multiple methods of comparisons. Power analysis suggests that, if real differences exist, the differences in forced vital capacity are <155 mL for males, <105 mL for females, and the differences in forced expiratory volume in one second are <107 mL for males and <76 mL for females.     

Comparison of Indian reference equations for spirometry interpretation

BACKGROUND AND OBJECTIVES: It would be desirable in a large country such as India that a single set of reference equations be used to interpret lung function tests performed across the entire country. This study compared north, west and south reference equations in interpreting spirometry results in north Indian patients. METHODS: Spirometric records of 27,383 patients aged 16-65 years were assessed. Spirometric values for FVC, FEV(1) and FEV(1)%FVC values derived from north, west and south Indian reference equations were compared. Differences in the lower limit of normal (LLN) were studied across the age and height range of the study group to determine if there was any clinically significant difference in the three derived values. RESULTS: The north and west Indian equations was discordant in 22.1% instances, and the north and south Indian equations in 12.9% instances, with kappa estimates of agreement being 0.626 and 0.781, respectively. Most of the patients with abnormal spirometry using north Indian equations were erroneously interpreted to have normal spirometry using west or south Indian equations. The south Indian equations underpredicted LLN for FVC and FEV(1) for most men and women. The west Indian equations underpredicted LLN for FVC and FEV(1) in all men, and in younger and short statured women. CONCLUSIONS: North, west and south Indian reference equations do not yield equivalent results for spirometry interpretation in north Indian patients.     

广州地区诱导痰细胞学正常参考值的建立

目的 建立广州地区正常人诱导痰细胞总数及分类的正常范围。方法 对117例正常非吸烟的自愿者进行高渗盐水雾化痰诱导,并对诱导痰液中细胞总数及细胞分类进行检测和统计分析。结果 108例自愿者（男60例,女48例）成功诱导出痰液,诱导痰成功率为94.2%,细胞总数和分类结果的x^-±2SD、中位数（四分位数间距）分别为,细胞总数：2.32±3.54、2.1（1.6）%,中性粒细胞：46.9±52.3、42.9（41.2）%,巨噬细胞：51.2±52.3、55.8（41.3）%,嗜酸粒细胞：0.4±1.6、0.0（0.5）%,淋巴细胞：1.4±2.8、1.0（2.0）%。正常男女对照的各种参考值范围结果无统计学差异。结论 本研究初步建立了本地区诱导痰细胞总数及细胞分类的正常参考值范围,在研究气道炎症的特征和相应患者的诊疗等方面具有一定的意义。