Normal Spirometric Reference Values for Omani Adults

International guidelines recommend the use of population-specific reference values to eliminate the well-recognized influence of ethnic variation on lung function. This study was designed to derive spirometric prediction equations for healthy Omani adults. Forced vital capacity (FVC), forced expiratory volume in one second (FEV₁), peak expiratory flow rate (PEFR), and forced expiratory flow at 25% to 75% of FVC (FEF_25–75%) were measured in 419 “healthy” nonsmoking Omani adults (256 men, 163 women), aged 18–65 years. Multiple linear regression analysis was performed for each spirometric parameter against age, height, and weight for men and women separately, and prediction equations for all the above parameters were derived and compared with values derived using equations published from other populations. All measured spirometric parameters increased with height and decreased with age, and they were all significantly higher in men. In contrast, FEV₁/FVC% values decreased with height and increased with age and were higher in women. The predicted normal values of FVC and FEV₁ for our subjects using the derived equations were lower by 7–17% compared with respective Caucasian values, with smaller difference in the predicted values of PEFR, FEV₁/FVC%, and FEF_25–75%. This report presents previously unavailable spirometric reference equations for the Omani adults. Our findings highlight the need to use reference values based on updated data derived from relevant populations.     

Normal spirometric reference values for Omani children and adolescents

OBJECTIVES: Normal lung function has been shown to be population specific. The aim of this study was to derive normal reference spirometric values for Omani children and adolescents. METHODOLOGY: Forced vital capacity (FVC), forced expiratory volume in 1 s (FEV(1)), peak expiratory flow and forced mid-expiratory flow were measured in 837 healthy Omani school children aged 6-19 years. Multiple linear regression analysis was performed for each spirometric parameter against age, height and weight for boys and girls separately. RESULTS: All measured spirometric parameters increased with age and height and were significantly higher in boys than girls. Height explained the maximum variance for all parameters. After accounting for height in the prediction equations, the contribution of age and weight was minimal. The expiratory ratio (FEV(1)%FVC) was independent of age and height and its mean values (+/- standard deviation) were slightly higher in girls (91.1 +/- 6.1%) than boys (86.5 +/- 7.1%; P < 0.001). The predicted normal values of the subjects using the derived equations were between 5 and 10% lower than the respective values for subjects in Caucasian sample groups. CONCLUSION: The developed prediction equations can be used in clinical practice in Oman and can be considered for use in neighbouring Arab countries.     

Prediction equations for lung function in healthy, life time never-smoking Malaysian population

Several equations have been used to predict lung function standard results for different populations. It is important lung function evaluations use appropriate standards for the study population. The objective of this study was to develop a prediction equation for lung function test results for the Malaysian population. Spirometry was performed among 5,708 subjects and 1,483 healthy, lifetime never smoked subjects (386 males and 1,097 females). Prediction equations were derived for both men and women for FVC and FEV1 results. The equations were validated on new subjects (n = 532, 222 males and 310 females) who met the same inclusion and exclusion criteria as the main cohort. There was a positive correlation between the measured values and the values derived from the new prediction equations (0.62 for FEV1 and between 0.66 and 0.67 for FVC; both p < 0.05) for both men and women with a smaller bias and limit of agreement compared to the published reference equations of ECCS, Knudson, Crapo and NHANES III. The reference equations derived from local spirometry data were more appropriate than generally used equations based on data from previous studies in different population.     

New predictive equations for spirometric reference values and comparison with Morris equation in a Korean population

Background and objective:   The clinical importance of the differences between actual and predicted spirometric indices in non-Western populations is poorly defined. This study evaluated the differences between the spirometric values derived from Morris equation, traditionally used in South Korea, and the actual values, in the classification and detection of patients with respiratory diseases, and developed new predictive equations for the calculation of reference spirometric values for healthy Koreans.
Methods:   Data derived from a subset of the population who completed the initial baseline survey of the Korean Health and Genome Study were used to develop new predictive equations for spirometric reference values, using multiple linear regression. The effects of the new equations relative to those of Morris on the detection and classification of patients with respiratory diseases were then evaluated.
Results:   In total, 9999 people completed the baseline survey; a subgroup of 1314 met the study inclusion criteria and were used to develop the new predictive equations. Morris equation are 53.8% less accurate in detecting people with restrictive disorders and 15.8% less accurate in estimating the severity of COPD than the newly derived equations, although the differences between values derived from the traditional equations and values from the new equations were as small as 3.3–7.6%.
Conclusions:   The use of spirometric reference values that underestimate the actual parameters, despite the small differences, may have a significant influence on the detection of patients with restrictive disorders and the staging of COPD.     

Spirometric reference equations for European females and males aged 65-85 yrs.

The aim of this study was to describe spirometric reference equations for healthy never-smoking European adults aged 65-85 yrs and to compare the predicted values of this sample with those from other studies including middle-aged and/or older adults. Reference equations and normal ranges for forced expiratory volume in one second (FEV1), forced vital capacity (FVC), forced expiratory volume in six seconds (FEV6), FEV1/FVC ratio and FEV1/FEV6 ratio were derived from a healthy subgroup of 458 subjects aged 65-85 yrs. Spirometry examinations followed the 1994 American Thoracic Society recommendations and the quality of the data was continuously monitored and maintained. Reference values and lower limits of normal were derived using a piecewise polynomial model with age and height as predictors. The reference values of FEV1 and FVC from the present study were higher than those given by prediction equations from the European Community for Coal and Steel. By contrast, use of prediction equations from Caucasian-American elderly subjects (Cardiovascular Health Study) consistently overpredicted FVC and FEV1 in females by 8.5 and 2.1%, respectively. In males, equations from the Cardiovascular Health Study overpredicted FVC by 2.8%, whilst underpredicting FEV1 by 2.5%. In conclusion, these results underscore the importance of using prediction equations appropriate to the origin, age and height characteristics of the subjects being studied.     

Lung function values in healthy non-smoking urban adults in iran

BACKGROUND: The values of lung function tests (LFTs) are dependent on height, age, and sex. In addition, there is evidence of LFT variation in different ethnic groups. OBJECTIVE: We have therefore derived prediction equations for LFTs from a healthy, non-smoking, urban adult population in the city of Mashhad (northeast Iran). METHODS: Predicted equations for normal lung function have been derived from 572 healthy, non-smoking subjects including 326 men (height 154-195 cm) and 246 women (height 144-174 cm) aged 18-65 years. The subjects underwent measurement of spirometric flow and volume. The following variables were measured: forced vital capacity (FVC), forced expiratory volume in 1 s (FEV(1)), maximal mid-expiratory flow (MMEF), peak expiratory flow (PEF) and maximal expiratory flow at 75, 50 and 25% of the FVC (MEF(75), MEF(50), and MEF(25), respectively). Regression analysis using height and age as independent variables was applied to provide predicted values for both sexes. RESULTS: There was a negative correlation between each lung function and age. The largest negative correlations were found for FEV(1) and FVC in men and women, respectively. All parameters correlated positively with height; the largest positive correlation was observed for FVC in both sexes. Comparison of LFTs derived from the equations of the present study showed significant differences with those of several previous studies. CONCLUSION: In this study, a set of LFT reference values and prediction equations for both sexes have been derived using a relatively large, healthy, non-smoking Iranian, adult population which was different from several other prediction equations.     

Spirometric lung volumes in the adult Pacific Islander population: comparison with predicted values in a European population

OBJECTIVE: Prediction equations for spirometric lung volumes have been developed mainly in Europe and North America and may not be relevant to Pacific Islanders. This study was undertaken to determine whether currently available prediction equations adequately describe spirometric lung volumes in the asymptomatic adult Pacific Islander population. METHODOLOGY: Healthy asymptomatic Pacific Island adults aged 15-70 years were recruited. Pulmonary function was measured in the laboratory at Green Lane Hospital, Auckland, New Zealand, in accordance with American Thoracic Society standards. Measured results were compared with predicted values derived from four sets of prediction equations relevant to, or currently used in, New Zealand. RESULTS: A total of 101 volunteers took part in the study; mean age 28 years (range 18-66 years), 39% male, body mass index = 32 (range 22-54). For forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC), when measured values were compared with reference values, the slopes of the regression lines were not significantly different from 1 and the intercepts were not significantly different from zero. Prediction equations derived for African-Americans did not provide a better fit than the prediction equations for Caucasians. Predictions were improved when ideal rather than actual bodyweight was used. CONCLUSION: Respiratory parameters (FEV1 and FVC) in healthy asymptomatic adult Pacific Islanders in New Zealand are adequately described by currently available prediction equations and no adjustment for ethnicity is required.     

Spirometric prediction equations for Hispanic children and adults in New Mexico

We conducted a population-based survey of respiratory diseases and lung function in a New Mexico Hispanic community, and developed spirometric prediction equations based on data from 576 children and adults. Spirometric test procedures were followed as recommended by the American Thoracic Society. For children 6 through 18 yr of age, we used a logarithmic model to predict spirometric parameters. We used simple linear regression for adults 25 through 80 yr of age. On the basis of exploratory analyses, we excluded adult subjects who were obese, defined as a body mass index of 30 kg/m2 or greater. This report describes these regressions. We did not perform regression analysis for those subjects between 19 and 24 yr of age because of small numbers and the inappropriateness of grouping these subjects with older adults for regression analysis. As an alternative to a regression equation for this age group specifically, we propose linear interpolation between values obtained using prediction equations developed for children and for adults. Finally, we compared the percent predicted values obtained from our internal prediction equations with equations from other populations of white children and adults. In general, the comparison equations underestimated the percent predicted values in our population.     

Post-bronchodilator spirometry reference values in adults and implications for disease management

RATIONALE: International guidelines promote the use of post-bronchodilator spirometry values in the definition and severity classification of chronic obstructive pulmonary disease. However, post-bronchodilator reference values have not yet been developed. OBJECTIVES: To derive reference values for post-bronchodilator forced expiratory volume in one second (FEV1), forced vital capacity (FVC), and FEV1/FVC, and to compare these reference values with locally derived and existing pre-bronchodilator reference values. METHODS: Based on a random sample of a general adult population, 2,235 subjects (70% of invited subjects) performed spirometry with reversibility testing. A reference population of healthy never-smokers constituted 23% of the study population (n=515). Reference values for median and lower-limit-of-normal pre- and post-bronchodilator lung function and bronchodilator response were modeled using quantile regression analyses. MAIN RESULTS: The reference population had equal proportions of men and women in the age range 26-82 yr. Both FEV1 and FVC decreased with age and increased with height. FEV1/FVC decreased with age, although this trend was not statistically significant for men after bronchodilatation. Linear models gave the best overall fit. Lower-limit-of-normal post-bronchodilator FEV1/FVC exceeded 0.7 for both sexes. Post-bronchodilator prediction equations gave higher predicted FEV1 and FEV1/FVC than both locally derived and existing pre-bronchodilator equations. The bronchodilator response decreased with age. CONCLUSIONS: The present study is the first to develop reference values for post-bronchodilator lung function. Post-bronchodilator prediction equations can facilitate better management of patients with chronic obstructive pulmonary disease by avoiding falsely high FEV1% predicted with a subsequent underestimation of disease severity.     

Prediction equations for pulmonary function values in healthy young Iranians aged 8-18 years

OBJECTIVE: Pulmonary function test (PFT) variables are dependent on height, age and gender. In addition, there is evidence of PFT variation in different ethnic groups. Prediction equations for PFT from a healthy, non-smoking, urban young population in the city of Mashhad (north-east Iran) have been derived. METHODOLOGY: Prediction equations for normal pulmonary function were derived from 336 healthy, non-smoking subjects, including 187 males (height 103-188.5 cm) and 149 females (height 104-183 cm) aged 8-18 years. The subjects underwent measurement of spirometric flow and volume. The following variables were measured: FVC, FEV1, maximal mid-expiratory flow (MMEF), PEF, maximal expiratory flow at 75, 50 and 25% of the FVC (MEF75, MEF50, and MEF25, respectively), tidal volume (VT), inspiratory reserve volume (IRV), expiratory reserve volume (ERV), inspiratory capacity (IC), and vital capacity (VC). Regression analysis using height and age as independent variables was applied to provide predicted values for both genders. RESULTS: There were positive correlations for each pulmonary function variable with height and age. The largest positive correlations were found for FEV1 with height and age, in both genders. Comparison of PFT variables derived from the equations obtained in the present study showed significant differences to those calculated from several previously published equations (P < 0.001 for most variables). For example, the values of FVC and FEV1 derived from the equations obtained in the present study were 2.83 +/- 0.99 and 2.50 +/- 0.89 for males, and 2.41 +/- 0.54 and 2.19 +/- 0.53 for females, while the values derived from the equations of the European Community for Steel and Coal study were 3.12 +/- 1.06 and 2.62 +/- 0.89 for males and 2.79 +/- 0.67 and 3.35 +/- 0.57 for females, respectively. CONCLUSIONS: A set of PFT reference values and prediction equations for both genders has been derived using a relatively large, healthy, non-smoking Iranian young population, and has generated results that differ from several other prediction equations.     

Canadian prediction equations of spirometric lung function for Caucasian adults 20 to 90 years of age: results from the Canadian Obstructive Lung Disease (COLD) study and the Lung Health Canadian Environment (LHCE) study

BACKGROUND:

Currently, no reference or normative values for spirometry based on a randomly selected Canadian population exist.

OBJECTIVE:

The aim of the present analysis was to construct spirometric reference values for Canadian adults 20 to 90 years of age by combining data collected from healthy lifelong nonsmokers in two population-based studies.

METHOD:

Both studies similarly used random population sampling, conducted using validated epidemiological protocols in the Canadian Obstructive Lung Disease study, and the Lung Health Canadian Environment study. Spirometric lung function data were available from 3042 subjects in the COLD study, which was completed in 2009, and from 2571 subjects in the LHCE study completed in 1995. A total of 844 subjects 40 to 90 years of age, and 812 subjects 20 to 44 years of age, were identified as healthy, asymptomatic, lifelong nonsmokers, and provided normative reference values for spirometry. Multiple regression models were constructed separately for Caucasian men and women for the following spirometric parameters: forced expiratory volume in 1 s (FEV₁), forced vital capacity (FVC) and FEV₁/FVC ratio, with covariates of height, sex and age. Comparison with published regression equations showed that the best agreement was obtained from data derived from random populations.

RESULTS:

The best-fitting regression models for healthy, never-smoking, asymptomatic European-Canadian men and women 20 to 90 years of age were constructed. When age- and height-corrected FEV₁, FVC and FEV₁/FVC ratio were compared with other spirometry reference studies, mean values were similar, with the closest being derived from population-based studies.

CONCLUSION:

These spirometry reference equations, derived from randomly selected population-based cohorts with stringently monitored lung function measurements, provide data currently lacking in Canada.     

Prediction equations for normal and low lung function from the Health Survey for England.

The aim of this study was to derive new spirometric reference equations for the English population, using the 1995/1996 Health Survey for England, a large nationally representative cross-sectional study. The measurements used were the forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) of a sample of 6,053 "healthy" (nonsmokers with no reported diagnosis of asthma or respiratory symptoms) White people aged > or = 16 yrs. Multiple regression analysis, with age and height as predictors, was carried out to estimate prediction equations for mean FEV1, FVC and FEV1/FVC, separately for males and females. A method based on smoothing multiple estimates of the fifth percentiles of residuals was used to derive prediction equations for the lower limit of normal lung function. The new equations fit the current English adult population considerably better than the European Coal and Steel Community equations, and the proportions of people with "low" (below the fifth percentile) lung function are closer to those expected throughout the whole adult age range (16 to > 75 yrs). For the age ranges the studies share in common, the new equations give estimates close to those derived from other nonlinear equations in recent studies. It is, therefore, suggested that these newly developed prediction equations be used for the White English population in both epidemiological studies and clinical practice.     

Updated spirometric reference values for adult Chinese in Hong Kong and implications on clinical utilization

STUDY OBJECTIVES: The accuracy of reference values of lung function is important for assessment of severity and functional impairment of respiratory diseases. The aim of the study was to establish updated prediction formulae of spirometric parameters for Hong Kong Chinese and to compare the reference values with those derived from other studies in white and Chinese subjects. DESIGN: Cross-sectional multicenter study. SETTING: Lung function laboratories of eight regional hospitals in Hong Kong. PARTICIPANTS: Subjects were recruited by random-digit dialing. One thousand one hundred seventy-six subjects who fulfilled recruitment criteria underwent spirometry. MEASUREMENTS: Spirometry was performed according to American Thoracic Society recommendations, and the technique was standardized among the eight participating lung function laboratories. RESULTS: Evaluable data of 1,089 (494 men and 595 women) healthy nonsmokers aged 18 to 80 years were analyzed. Age and height were found to be the major determinants of FEV1 and FVC, with a linear decline of height-adjusted values with age in both sexes. Spirometric values of this population have increased compared to Chinese populations of similar sex, age, and height two decades ago. Reference values derived from white populations were higher than our values by 5 to 19%, and the degree of overestimation varied with age, sex, and lung function parameter. We also demonstrated that the blanket application of correction factors for Asian populations may not be appropriate. In this study cohort, the distribution-free estimation of age-related centiles was more appropriate for the determination of lower limits of normal. CONCLUSIONS: Our findings underscore the need to use reference values based on updated data derived from local populations or those matched for ethnicity and other sociodemographic characteristics.     

Time domain spirogram indices. Their variability and reference values in nonsmokers

A cross-sectional population survey of dynamic ventilatory lung function was performed to determine the variability of and reference values for time domain spirogram indices. The reference population comprised 83 men and 143 women who were healthy nonsmokers. The time domain indices were derived from the blow with the largest sum of FVC and FEV1. Prediction equations for FEV1 and mean flow between 25 and 75% FVC were little influenced by methods for selecting the data from the 3 blows recorded. The variability of the first 2 moments of the spirogram increased with age, requiring a log transformation for regression analysis. Prediction equations for conventional and time domain spirometric indices are presented and reference values are proposed based on an estimated percentile derived from the predicted value and the residual standard deviation from regression. Two time domain indices are identified that may prove better suited than conventional indices for identifying abnormalities in the tail of the spirogram.     

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.     

Comparison of spirometric reference values

Lung-function reference values play a vital role in the management of respiratory disorders. There are many proposed reference equations for pediatric spirometry. Recently, spirometric reference equations were proposed, using data from people aged 8-80 years living in the US compiled by the third National Health and Nutrition Examination Survey. Our objective was to compare the predictive value of wider age-range reference equations to established pediatric reference equations for the pediatric population. Spirometry, height, and weight were obtained from 70 normal children aged 6-18 years. The difference between measured and predicted values as suggested by different reference equations was compared. Predicted values from general equations significantly differed from those generated from pediatric equations and from measured values in this population. The difference between measured and predicted values from the wider age-range equations varied between 7-16% for forced expired volume in 1 sec (FEV1) and forced vital capacity (FVC). The difference between measured and predicted values for the pediatric equations varied between 1-4%. Although wider age-range equations provide continuity through age ranges, their predictive accuracy may be low in the pediatric age group, especially for the youngest, smallest children. Extrapolating reference equations beyond the age range of subjects used to generate then is not recommended.     

Reference equations for spirometry from a general population sample in central Italy

Aim of this study was to derive new lung function reference equations and compare the predicted values with those from three sets of existing reference equations: one derived from a Northern Italy population and the two others widely used in European (ECCS) and American (NHANES III) clinical practice. Reference equations for flow-volume curve indexes and VC were derived on 497 normal subjects, aged 8-74, from the epidemiological survey in Pisa, Central Italy (1991-1993). By applying natural cubic splines, one single smooth and continuous equation for the entire age range was provided for each index, separately by gender. Along with age and height, reference values also depended on BMI. Differences among the four reference equations for FEV(1), FVC, VC were quantified for average subjects. The magnitude largely varied over the age range in both genders, reaching up to half litre of air volume at specific ages. Age-gender-specific prevalence rates of airway obstruction, as defined by the ERS criterion, largely varied by applying the considered equations, the differences ranging from -3% to 28%. The observed discrepancies confirm that reference equations should be derived from a population most similar to that for which the equations are to be used and based on measurements obtained by the same instrument and testing procedures, in order to minimize technical variability in lung function both for clinical and epidemiological purposes.     

Predictive values for cardiopulmonary exercise testing in sedentary Chinese adults

OBJECTIVE: Normative data for cardiopulmonary exercise testing (CPET) may vary among subjects of different races. The objectives of the present study were to: (i) establish normal standards for cardiopulmonary responses during incremental cycle ergometer testing in order to derive predictive equations for clinically useful variables during CPET of Chinese subjects; and (ii) determine the validity of existing prediction equations of maximal exercise performance for use in our local Chinese population. METHODOLOGY: The maximal and submaximal cardiopulmonary responses were analysed for 95 healthy sedentary adult Chinese subjects (48 men and 47 women; aged 20-70 years) who underwent CPET using a cycle ergometer and an incremental work-rate protocol until symptom limitation. RESULTS: Measurements, at maximal exercise, of oxygen uptake (VO2(max)), power output and heart rate were regressed on age, height, weight and gender. The predictive equations for these exercise parameters performed better than those published previously in out-sample predictive accuracy. Comparison with previous studies also showed that prediction equations of VO2(max) derived from studies based predominantly or exclusively on Caucasian populations overestimated the actual values for our subjects. CONCLUSIONS: Previously established prediction equations for maximal exercise performance during CPET based on non-Chinese populations may not be applicable to Chinese subjects in our population.     

Normative reference values for lung transfer factor in Isfahan, Iran

OBJECTIVES AND BACKGROUND: Transfer factor or carbon monoxide diffusing capacity (DL(CO)) is a particularly valuable test of the appropriateness of gas exchange across the alveolocapillary membrane. The purpose of this study is to derive predictive equations for DL(CO) and its derivative volume-corrected DL(CO) (DL(CO)/VA) measured by single-breath method in a large non-smoking population sample in Isfahan. METHODOLOGY: We evaluated 1429 randomly selected subjects (732 men, aged 5-85 years). Gender-specific linear prediction equations were developed by multiple regression analysis; with measured DL(CO), and DL(CO)/VA values (mmol/min/kPa), as dependent variables regressed against age (A), height (H) and body surface area (BSA). RESULTS: For both genders, age had negative effects on DL(CO), while height had a positive effect on DL(CO) and DL(CO)/VA (P < 0.01). The prediction equations for DL(CO) and DL(CO)/VA are: '0.152 x height - 0.056 x age - 11.595' and '-0.12 x age + 2.467', for men and: '-0.035 x age - 0.133 x height - 10.707' and '-0.012 x age - 0.02 x height + 2.755', for women, respectively. CONCLUSIONS: Our results therefore provide an original frame of reference for either DL(CO) or DL(CO)/VA in Iranian population, obtained from a standardized single-breath technique.     

Arm span as an independent predictor of pulmonary function parameters: validation and reference values

BACKGROUND AND OBJECTIVES: To determine if arm span can be used as a measure of body length in developing prediction equations for lung function and to compare these equations with height-derived equations. METHODS: Standing height and arm span were measured for all study subjects. Spirometry measurements included FVC, FEV(1), FEV(1)/FVC ratio, PEFR, FEF(25), FEF(50), FEF(75) and FEF(25-75). These data were used to develop prediction equations using multiple regression analysis based on age, gender and arm span. An independent group (225 subjects) was used to evaluate the accuracy of the equations. Predicted values for each parameter were calculated separately for arm span and height and compared with the measured values. RESULTS: Study subjects comprised 1865 healthy non-smoking Persian volunteers. Arm span-based equations accurately predicted all of the spirometric parameters. The standard errors of the estimate for prediction equations based on arm span were slightly smaller than those based on standing height. Average predicted values based on height predicted from arm span did not consistently agree with the measured values. CONCLUSIONS: Predicting pulmonary parameters using equations based on arm span is as reliable as using equations based on standing height and are more accurate for patients in whom height cannot be measured reliably.