Body mass, fat percentage, and fat free mass as reference variables for lung function: effects on terms for age and sex

Official ERS technical standard: Global Lung Function Initiative reference values for static lung volumes in individuals of European ancestry

BACKGROUND

Measurement of lung volumes across the life course is critical to the diagnosis and management of lung disease. The aim of the study was to use the Global Lung Function Initiative methodology to develop all-age multi-ethnic reference equations for lung volume indices determined using body plethysmography and gas dilution techniques.

METHODS

Static lung volume data from body plethysmography and gas dilution techniques from individual, healthy participants were collated. Reference equations were derived using the LMS (lambda-mu-sigma) method and the generalised additive models of location shape and scale programme in R. The impact of measurement technique, equipment type and being overweight or obese on the derived lung volume reference ranges was assessed.

RESULTS

Data from 17 centres were submitted and reference equations were derived from 7190 observations from participants of European ancestry between the ages of 5 and 80 years. Data from non-European ancestry populations were insufficient to develop multi-ethnic equations. Measurements of functional residual capacity (FRC) collected using plethysmography and dilution techniques showed physiologically insignificant differences and were combined. Sex-specific reference equations including height and age were developed for total lung capacity (TLC), FRC, residual volume (RV), inspiratory capacity, vital capacity, expiratory reserve volume and RV/TLC. The derived equations were similar to previously published equations for FRC and TLC, with closer agreement during childhood and adolescence than in adulthood.

CONCLUSIONS

Global Lung Function Initiative reference equations for lung volumes provide a generalisable standard for reporting and interpretation of lung volumes measurements in individuals of European ancestry.

Effects of fat distribution on lung function in young adults

Aims

To study the associations between fat distribution and lung functions in healthy subjects of young adults and to explore potential gender difference in these correlations.

Methods

A total of 2101 adult participants were recruited. Height, weight, and vital capacity index (VCI) were measured and recorded according to the national physical fitness test standard. Body compositions, including body mass index (BMI), body fat percentage (BFP), waist-to-hip ratio (WHR), fat-free mass (FFM), trunk muscle mass (TMM), fat mass (FM), visceral fat area (VFA), visceral adipose tissue (VAT), and subcutaneous adipose tissue (SAT), were conducted using body composition analyzer. Data were analyzed by SPSS 20.0 software.

Results

We found that male participants showed significantly higher BMI, WHR, FFM, TMM, VFA, and VCI, but lower FM, BFP, and SAT in comparison with women. However, there was no significant difference in VAT between the male and female. Lung functions represented by VCI were negatively correlated with FM, VAT, SAT, and VFA for both men and women (r < 0; P < 0.05). Among these negative correlations, VCI was more inversely correlated with VFA for men but with SAT for women, respectively. After dividing the whole populations by BMI, BFP, and WHR, further correlation analysis showed VCI was still more negatively correlated with VFA for all male subgroups (r < 0; P < 0.05). On the contrary, VCI was more negatively correlated with SAT in BMI-underweight, BMI-normal, BFP-low fat, BFP-normal fat, WHR-normal, and WHR-obese subgroups (r < 0; P < 0.05), while VFA and VAT was more inversely correlated with VCI in BMI- and BFP-overweight+obese subgroups (r < 0; P < 0.05).

Conclusions

Fat accumulation is highly associated with the vital capacity index in young adults. In general, VCI was more negatively correlated with VFA for men but with SAT for women, respectively, in comparison with other tested indices.

Fat-free mass index is superior to body mass index as a novel risk factor for prolonged air leak complicating video-assisted thoracoscopic surgery lobectomy for non-small-cell lung cancer

Background

To evaluate whether fat-free mass index (FFMI) could be predictive of prolonged air leak (PAL) complicating video-assisted thoracoscopic (VATS) lobectomy for non-small-cell lung cancer (NSCLC).

Methods

A retrospective study was conducted on the prospectively-maintained database in our institution between January 2015 and July 2017. The gender-specific median values of FFMI for males and females were applied as their respective cutoffs to stratify patients into low-FFMI group and high-FFMI group in initial univariable analyses. An effective multivariable logistic-regression analysis was then performed to demonstrate the predictive value of dichotomized FFMI.

Results

There were 1,091 surgical patients with NSCLC included (616 males and 475 females), with a PAL incidence of 14.6%. The median FFMI values among males and females were 17.3 and 14.6 kg/m², respectively. PAL cases in both male (16.9±1.5 vs. 17.4±1.5 kg/m²; P=0.002) and female (14.0±0.9 vs. 14.6±1.1 kg/m²; P<0.001) groups had a significantly lower mean FFMI than that of non-PAL cases. The incidence of PAL was significantly increased in male patients with FFMI <17.3 kg/m² (23.7% vs. 14.3%; P=0.003) and female patients with FFMI <14.6 kg/m² (12.7% vs. 5.0%; P=0.003). Lower dichotomized FFMI was also significantly associated with prolonged time to air leak cessation and length of stay (LOS). Finally, multivariable logistic-regression analysis indicated that lower dichotomized FFMI [odds ratio (OR) =1.98; 95% confidence interval (CI): 1.33-2.96; P=0.001] could independently predict the occurrence of PAL.

Conclusions

FFMI acts as an excellent categorical risk factor for PAL complicating VATS lobectomy and shows a much superior significance than body mass index (BMI) in terms of the prediction of PAL.

Metabolic health is more closely associated with decrease in lung function than obesity

Objective

Previous studies have evaluated the link between metabolic syndrome and obesity with impaired lung function, however findings have been controversial. We aimed to compare lung function among subjects with different metabolic health and obesity status.

Methods

Total 10,071 participants were evaluated at the Health Promotion Center in Seoul St. Mary’s Hospital between January 2012 and December 2014. Being metabolically healthy was defined as having fewer than three of the following risk factors: high blood pressure, high fasting blood glucose, high triglyceride, low high-density lipoprotein cholesterol and abdominal obesity. Obesity status was defined as body mass index (BMI) higher than 25 kg/m². Analyses of pulmonary function were performed in four groups divided according to metabolic health and obesity: metabolically healthy non-obese (MHNO), metabolically health obese (MHO), metabolically unhealthy non-obese (MUHNO), and metabolically unhealthy obese (MUHO).

Results

Metabolically unhealthy subjects were more prone to decreased lung function compared with their metabolically healthy counterparts, regardless of obesity status. When multinomial logistic regression analysis was performed according to quartiles of forced vital capacity (FVC) or forced expiratory volume in 1 second (FEV₁) (% pred), after adjusting for age, sex, and smoking status, odds ratio (OR) for the lowest FVC and FEV₁ (% pred) quartiles were significantly higher in MUHO subjects (1.788 [95% CI, 1.531–2.089] and 1.603 [95% CI, 1.367–1.881]) and lower in MHO subjects (0.768 [95% CI, 0.654–0.902] and 0.826 [95% CI, 0.700–0.976]) with MHNO group as the reference, when OR for highest FVC and FEV₁ quartiles were considered as 1.0

Conclusion

Metabolic health is more closely associated with impaired lung function than obesity.

Classical regression equations of spirometric parameters are not applicable for diagnosing spirometric abnormalities in adipotic adults

The prevalence of overweighing and obese adults (defined as “adipotic” adults), has markedly increased over the world. A remarkable increase in the adipotic population urgently needs developing the regression equations for predicting spirometric parameters (SPs), which are specifically applicable to adipotic adults. Unfortunately, however, the reliable equations suitable for adipotic adults have not been reported to date. Recently, Yamaguchi et al have proposed the quantitative method to estimate the effects of adiposity on deciding the SPs incorporating with age-specific contributions of various explanatory, independent variables such as age (A), standing height (H), body weight (BW), and fat fraction of body mass (F). Extending the method proposed by Yamaguchi et al, we attempted to elaborate the novel regression equations applicable for diagnosing the spirometric abnormality in adipotic adults. For accomplishing this purpose, never-smoking, adipotic adults with body mass index (BMI) over 25 kg/m² and no respiratory illness were recruited from the general population in Japan (n = 3696, including men: 1890 and women: 1806). Introducing the four explanatory variables of A, H, BW, and F, gender-specific and age-dependent regression equations that allowed for prescribing the SPs in adipotic adults were constructed. Comparing the results obtained for non-adipotic adults (i.e., those with normal BMI), the negative or positive impact of height on SPs was preserved in adipotic adults, as well. However, the negative impact of age on SPs was blunted in adipotic men and the positive effect of BW on SPs was impeded in adipotic men and women. The fat fraction of body mass-elicited negative impact on SPs vanished in adipotic women. These results indicate that the regression equations of SPs for adipotic adults differ significantly from those for non-adipotic adults, leading to the conclusion that the regression equations for non-adipotic adults should not be used while judging the spirometric abnormalities in adipotic adults.

The effects of truncal adiposity in forced spirometry: Sex differences

The aim of the current paper is to establish the influence of truncal fat accumulation on the spirometric results of a group of healthy individuals. A cross-sectional study of 305 healthy, non-smoking adult subjects (144 males, 161 females) was conducted. Forced spirometry and dual-energy X-ray absorptiometry to quantify body fat were performed. Partial correlation and multiple linear regression analyses were performed. In females, abdominal fat was negatively correlated with forced vital capacity (FVC) and forced expiratory volume in one second (FEV₁). In males, thoracic fat was negatively correlated with respiratory variables, as was abdominal fat. In the multiple linear regression, FEV₁ was the spirometric parameter that showed higher R² values in both sexes. Truncal fat had a greater influence on FEV₁ than on FVC. In males, no significant differences between the influence of thoracic and abdominal fat on spirometric results were found, and total body fat was shown to have more influence than regional. In females, the influence of abdominal fat was higher.

Influence of Socioeconomic and Anthropometric Factors on Respiratory Function in Female University Students

The purpose of this study was to evaluate lung function in healthy young female university students and to seek the relation of lung function to socioeconomic and anthropometric indices. The methodology consisted of spirometry tests, anthropometric measures and a questionnaire conducted in November of 2015 among 152 female university students. At first, lung function was analyzed for any relationship with socioeconomic factors and smoking. The results of a multi-factor analysis of variance demonstrate significant differences in the FEV1/FVC ratio depending on the general socioeconomic status. Then, anthropometric and spirometric parameters were tested for correlations. A comparison of underweight, normal weigh, overweight, and obese subjects revealed statistically significant differences for FVC% and FEV1/FVC, with the highest values noted in the subjects of normal weight. Individuals with abdominal obesity had lower FVC% and FEV1% and a higher FEV1/FVC ratio. The findings of our study confirm that both general obesity and abdominal obesity are related to a reduced lung function.

The training type influence on male elite athletes' ventilatory function

Background/aim

To assess and compare measured ventilatory volumes (forced expiratory volume in 1 s (FEV₁), peak expirium flow (PEF) and maximal voluntary ventilation (MVV)), ventilatory function capacities (forced vital capacity (FVC) and vital capacity (VC)) and FEV₁/VC ratio in a sample of power and endurance elite athletes and their age-matched and sex-matched sedentary control group.

Methods

A cross-sectional study was applied on male elite athletes (n=470) who were classified according to the type of the predominantly performed exercise in the following way: group 1: endurance group (EG=270), group 2: power athletes group (SG=200) and group 3: sedentary control group (CG=100). The lung VC, FVC, FEV₁, FEV₁/FVC ratio, PEF and MVV were measured in all of the observed subjects, who were also classified with regard to body mass index (BMI) and the percentage of the body fat (BF%).

Results

The CG had the highest BF% value, while the endurance group had the lowest BMI and BF% value, which is significantly different from the other two groups (p<0.05). The observed values of VC, FVC and FEV₁ in the EG were significantly higher than those from the other two groups (p<0.05). There were no differences concerning the observed FEV₁/FVC ratio.

Conclusions

A continued endurance physical activity leads to adaptive changes in spirometric parameters (VC, FVC and FEV₁), highlighting the fact that there is a need for specific consideration of different respiratory ‘pattern’ development in different types of sport, which also has to be further evaluated.

Relationship of Muscle Mass Determined by DEXA with Spirometric Results in Healthy Individuals

INTRODUCTION

Muscle mass maybe a determining factor in the variability of spirometry results in individuals of the same sex and age who have similar anthropometric characteristics. The aim of this study was to determine the association between spirometric results from healthy individuals and their muscle mass assessed by dual energy X-ray absorptiometry (DEXA).

METHODS

A sample of 161 women and 144 men, all healthy non-smokers, was studied. Ages ranged from18 to77years. For each subject, spirometry results and total and regional lean mass values obtained by full body DEXA were recorded. A descriptive analysis of the variables and a regression analysis were performed to study the relationship between spirometric variables and lean body mass, correcting for age and body mass index (BMI).

RESULTS

In both sexes all muscle mass variables correlated positively and significantly with spirometric variables, and to a greater extent in men. After partial adjustment of correlations by age and BMI, the factor which best explains the spirometric variables is the total lean body mass in men, and trunk lean body mass in women.

CONCLUSIONS

In men, muscle mass in the lower extremities is most closely associated with spirometric results. In women, it is the muscle mass of the trunk. In both sexes muscle mass mainly affects FEV₁.

Relationship between Body Composition and Pulmonary Function in Early Adult Life: A Cross-Sectional Analysis Nested in Two Birth Cohort Studies

BACKGROUND

Overweight/obesity has been reported to worsen pulmonary function (PF). This study aimed to examine the association between PF and several body composition (BC) measures in two population-based cohorts.

METHODS

We performed a cross-sectional analysis of individuals aged 18 and 30 years from two Pelotas Birth Cohorts in southern Brazil. PF was assessed by spirometry. Body measures that were collected included body mass index, waist circumference, skinfold thickness, percentages of total and segmented (trunk, arms and legs) fat mass (FM) and total fat-free mass (FFM). FM and FFM were measured by air-displacement plethysmography (BODPOD) and by dual-energy x-ray absorptiometry (DXA). Associations were verified through linear regressions stratified by sex, and adjusted for weight, height, skin color, and socioeconomic, behavioral, and perinatal variables.

RESULTS

A total of 7347 individuals were included in the analyses (3438 and 3909 at 30 and 18 years, respectively). Most BC measures showed a significant positive association between PF and FFM, and a negative association with FM. For each additional percentage point of FM, measured by BOD POD, the forced vital capacity regression coefficient adjusted by height, weight and skin color, at 18 years, was -33 mL (95% CI -38, -29) and -26 mL (95% CI -30, -22), and -30 mL (95% CI -35, -25) and -19 mL (95% CI -23, -14) at 30 years, in men and women, respectively. All the BOD POD regression coefficients for FFM were the same as for the FM coefficients, but in a positive trend (p<0.001 for all associations).

CONCLUSIONS

All measures that distinguish FM from FFM (skinfold thickness-FM estimation-BOD POD, total and segmental DXA measures-FM and FFM proportions) showed negative trends in the association of FM with PF for both ages and sexes. On the other hand, FFM showed a positive association with PF.

The relationship between body fat and respiratory function in young adults

The relationship between adiposity and respiratory function is poorly understood. Most studies investigating this have used indirect measures of body fat and few have assessed how changes in adiposity influence lung function.Body fat measured by bio-electrical impedance analysis, body mass index, waist circumference, spirometry, body plethysmography and transfer factor were measured at ages 32 and 38 years in 361 non-smoking, non-asthmatic participants from a population-based birth cohort.Higher percentage body fat was associated with lower spirometric and plethysmographic lung volumes, but not with airflow obstruction, or transfer factor at 32 years. Changes in adiposity between ages 32 and 38 years were inversely associated with changes in lung volumes. These associations were generally stronger in men than women, but an association between increasing adiposity and lower airway function (forced expiratory volume in 1 s/forced vital capacity) was only found in women. Similar associations were found for body mass index and waist circumference.Higher percentage body fat is associated with lower lung volumes. Direct and indirect measures of adiposity had similar associations with lung function. Adiposity had a greater effect on lung volumes in men than women but was associated with airway function only in women. There was little evidence that adiposity influenced transfer factor.

Abdominal adiposity is an early marker of pulmonary function impairment: Findings from a Mediterranean Italian female cohort

BACKGROUND AND AIMS

Abdominal adiposity may influence the respiratory function, especially in women. The aim of this prospective study is to evaluate the predictive role of body mass index (BMI) and waist circumference (WC) on lung function in healthy women.

METHODS AND RESULTS

In 600 women randomly selected from the cohort of the "Progetto ATENA," anthropometric measures such as BMI, WC, and weight gain were recorded at baseline, and the spirometric parameters were measured 10 years later. The percentage values of forced expiratory volume in 1 s (FEV1%) and forced vital capacity (FVC%) and the ratio of FEV1/FVC were compared with the anthropometric measures after adjustment for several variables measured at baseline such as age, height, socioeconomic status, smoking habits, and history of respiratory allergies grouped in a basal model. WC is significantly associated with a decreased FVC (p = 0.008) and an increased ratio of FEV1/FVC (p = 0.031) after adjustment for the covariates of the basal model. The association between BMI and spirometric parameters reaches borderline significance only with the ratio of FEV1/FVC (p = 0.052).

CONCLUSIONS

We suggest measuring both BMI and WC to assess the risk of future respiratory impairment.

Emerging Comorbidities in Adult Asthma: Risks, Clinical Associations, and Mechanisms

Asthma is a heterogeneous disease with many phenotypes, and age at disease onset is an important factor in separating the phenotypes. Most studies with asthma have been performed in patients being otherwise healthy. However, in real life, comorbid diseases are very common in adult patients. We review here the emerging comorbid conditions to asthma such as obesity, metabolic syndrome, diabetes mellitus type 2 (DM2), and cardiac and psychiatric diseases. Their role as risk factors for incident asthma and whether they affect clinical asthma are evaluated. Obesity, independently or as a part of metabolic syndrome, DM2, and depression are risk factors for incident asthma. In contrast, the effects of comorbidities on clinical asthma are less well-known and mostly studies are lacking. Cross-sectional studies in obese asthmatics suggest that they may have less well controlled asthma and worse lung function. However, no long-term clinical follow-up studies with these comorbidities and asthma were identified. These emerging comorbidities often occur in the same multimorbid adult patient and may have in common metabolic pathways and inflammatory or other alterations such as early life exposures, systemic inflammation, inflammasome, adipokines, hyperglycemia, hyperinsulinemia, lung mechanics, mitochondrial dysfunction, disturbed nitric oxide metabolism, and leukotrienes.

The relationship between serum fatty-acid binding protein 4 level and lung function in Korean subjects with normal ventilatory function

Background

The aim of this study was to assess the association of lung function with serum fatty-acid binding protein 4 (FABP4) in apparently healthy Korean adults.

Methods

In 495 participants in a health screening program, Force Exploratory Volume (FEV) 1 and Forced Vital Capacity (FVC) were assessed with standard spirometry. Subjects with obstructive (n = 19) and restrictive (n = 45) lung function were excluded from the analysis. Serum FABP4 level was measured by enzyme-linked immunosorbent assay and transformed into Ln(FABP4). 431 subjects with normal ventilator function (72.4 % men, mean age 41 years) were included in the final analysis.

Results

Mean Ln(FABP4) significantly decreased in subjects from 1^st quartile to 4^th quartile of FVC (p = 0.008). Ln(FABP4) did not show significant differences across the quartile groups of FEV1. The odds ratio (OR) of being in the lowest quartile of FVC was 2.704 in subject with 3^rd tertile of Ln(FABP4) after full adjustment for confounding variables {95 % confidence interval (CI) 1.397 ~ 5.357}. OR of being in the lowest quartile of FEV1 was 1.822 (95 % CI 1.021 ~ 3.298) in subjects with 3^rd tertile of Ln(FABP4) after adjustment of age and sex, which was attenuated after full adjustment for confounding variables.

Conclusion

Increased FABP4 level showed increased risk for reduced lung function in subjects with normal ventilatory function.

Electronic supplementary material

The online version of this article (doi:10.1186/s12890-016-0190-8) contains supplementary material, which is available to authorized users.

Implication of Sarcopenia and Sarcopenic Obesity on Lung Function in Healthy Elderly: Using Korean National Health and Nutrition Examination Survey

Previous studies have demonstrated a positive association between obesity and decreased lung function. However, the effect of muscle and fat has not been fully assessed, especially in a healthy elderly population. In this study, we evaluated the impact of low muscle mass (LMM) and LMM with obesity on pulmonary impairment in healthy elderly subjects. Our study used data from the Korea National Health and Nutrition Examination Survey from 2008 to 2011. Men and women aged 65 yr or older were included. Muscle mass was measured by dual-energy X-ray absorptiometry. LMM was defined as two standard deviations below the sex-specific mean for young healthy adults. Obesity was defined as body mass index ≥ 25 kg/m(2). The prevalence of LMM in individuals aged over 65 was 11.9%. LMM and pulmonary function (forced vital capacity and forced expiratory volume in 1 second) were independently associated after adjusting for age, sex, body mass index, smoking status, alcohol consumption, and frequency of exercise. LMM with obesity was also related to a decrease in pulmonary function. This study revealed that LMM is an independent risk factor of decreased pulmonary function in healthy Korean men and women over 65 yr of age.

Respiratory parameters in elite athletes--does sport have an influence?

INTRODUCTION

Unlike large population studies about cardiovascular components and how they adapt to intensive physical activity, there is less research into the causes of enlargement of the respiratory system in athletes (e.g. vital capacity, maximum flow rates and pulmonary diffusion capacity). The purpose of this research was to study and compare pulmonary function in different types of sports and compare them with controls in order to find out which sports improve lung function the most.

MATERIALS AND METHOD

Pulmonary functional capacities, vital capacity (VC), forced vital capacity (FVC), forced expiratory volume in one second (FEV1) and maximum voluntary ventilation (MVV) of 493 top athletes belonging to 15 different sports disciplines and of 16 sedentary individuals were studied. Pulmonary function test was performed according to ATS/ERS guidelines.

RESULTS

Basketball, water polo players and rowers had statistically higher vital capacity (VC), forced vital capacity (FVC), forced expiratory volume in one second (FEV1) than the healthy sedentary control individuals. Football and volleyball players had lower VC while FVC was higher in the football group compared to controls. Peak expiratory flow was lower in boxing, kayak, rugby, handball, taekwondo and tennis. The maximum voluntary ventilation (MVV) was significantly higher in water polo players and rowers. Boxers had statistically lower MVV than the controls. Players of other sports did not differ from the control group.

CONCLUSION

The study suggests that specific type of training used in basketball, water polo or rowing could have potential for improving pulmonary function and rehabilitation.

Evolution of the COPD Assessment Test score during chronic obstructive pulmonary disease exacerbations: determinants and prognostic value

BACKGROUND

An adequate evaluation of exacerbations is a primary objective in managing patients with chronic obstructive pulmonary disease (COPD).

OBJECTIVES

To define the profile of health status recovery during severe exacerbations of COPD using the COPD Assessment Test (CAT) questionnaire and to evaluate its prognostic value.

METHODS

Forty-five patients with previous COPD diagnoses who were hospitalized due to severe exacerbation(s) were included in the study. These patients were treated by their respective physicians following current recommendations; health status was assessed daily using the CAT questionnaire. The CAT score, spirometry and recurrent hospitalizations were recorded one and three months after hospital discharge.

RESULTS

Global initiative for chronic Obstructive Lung Disease (GOLD) stage was an independent determinant for increased CAT score during the first days of exacerbation with respect to postexacerbation values. From hospitalization day 5, the CAT score was similar to that obtained in the stable phase. Body mass index, GOLD stage and education level were related to health status recovery pattern. CAT score increase and the area under the curve of CAT recovery were inversely related to the forced expiratory volume in 1 s achieved three months after discharge (r=-0.606; P<0.001 and r=-0.532; P<0.001, respectively). Patients with recurrent hospitalizations showed higher CAT score increases and slower recovery.

CONCLUSIONS

The CAT detects early health status improvement during severe COPD exacerbations. Its initial worsening and recovery pattern are related to lung function and recurrent hospitalizations.

A large cohort study concerning age-dependent impacts of anthropometric variables on spirometric parameters in nonsmoking healthy adults

BACKGROUNDS

Although height (H) has been considered the principal anthropometric variable governing lung function, the age-dependent differences in its influences on determining spirometric parameters (SPs) have not been conclusively investigated. Moreover, there has been no study centered on age-dependent effects of other anthropometric variables, including body weight (BW) and body fat mass (BFM) on SPs. In addition, the age-dependent influences of these anthropometric variables are anticipated to differ quantitatively between male and female participants.

METHODS

A total of 16,919 nonsmoking healthy Japanese adults (men: 6,116, women: 10,803) were partitioned into six groups stratified by gender and age at intervals of 20-years: young-, middle-, and advanced-age groups of either gender. Using a model in which a SP was described by a logarithmic additive function of age, H, BW, and BFM, we determined the partial regression coefficients of the respective anthropometric variables to predict the reference means of SPs, including FVC, FEV1, FEV1/FVC, PEF, FEF50, and FEF75, in the six groups.

RESULTS/DISCUSSION

Although the impact of H on FVC and FEV1 was relatively homogeneous irrespective of gender and age, its homogeneity faded for flow parameters, particularly in the female middle- and advanced-age groups, indicating that the age-dependent contribution of H to SPs was enhanced more in women. The impact of BW on SPs differed depending on age, and this effect was also more conspicuous for female participants. H and BW generally exerted positive effects on SPs, whereas BFM had negative effects. Opposite effects of BW and BFM were observed in the female middle-age group in particular.

CONCLUSIONS

The effects of anthropometric variables on spirometric parameters are highly age-dependent, particularly in women, leading to the conclusion that the assumption of age-independent, constant partial regression coefficients of anthropometric variables while predicting the reference mean of a certain spirometric parameter may result in substantial errors.

Obesity and asthma: physiological perspective

Obesity induces some pertinent physiological changes which are conducive to either development of asthma or cause of poorly controlled asthma state. Obesity related mechanical stress forces induced by abdominal and thoracic fat generate stiffening of the lungs and diaphragmatic movements to result in reduction of resting lung volumes such as functional residual capacity (FRC). Reduced FRC is primarily an outcome of decreased expiratory reserve volume, which pushes the tidal breathing more towards smaller high resistance airways, and consequentially results in expiratory flow limitation during normal breathing in obesity. Reduced FRC also induces plastic alteration in the small collapsible airways, which may generate smooth muscle contraction resulting in increased small airway resistance, which, however, is not picked up by spirometric lung volumes. There is also a possibility that chronically reduced FRC may generate permanent adaptation in the very small airways; therefore, the airway calibres may not change despite weight reduction. Obesity may also induce bronchodilator reversibility and diurnal lung functional variability. Obesity is also associated with airway hyperresponsiveness; however, the mechanism of this is not clear. Thus, obesity has effects on lung function that can generate respiratory distress similar to asthma and may also exaggerate the effects of preexisting asthma.

The effect of body composition on pulmonary function

Background

The pulmonary function test is the most basic test method to diagnosis lung disease. The purpose of this study was to research the correlation of the body mass index (BMI), the fat percentage of the body mass (fat%), the muscle mass, the fat-free mass (FFM) and the fat-free mass index (FFMI), waist-hip ratio (WHR), on the forced expiratory volume curve.

Methods

Between March and April 2009, a total of 291 subjects were enrolled. There were 152 men and 139 female (mean age, 46.3±9.92 years), and they were measured for the following: forced vital capacity (FVC), forced expiratory volume at 1 second (FEV₁), and forced expiratory flow during the middle half of the FVC (FEF_25-75) from the forced expiratory volume curve by the spirometry, and the body composition by the bioelectrical impedance method. Correlation and a multiple linear regression, between the body composition and pulmonary function, were used.

Results

BMI and fat% had no correlation with FVC, FEV₁ in male, but FFMI showed a positive correlation. In contrast, BMI and fat% had correlation with FVC, FEV₁ in female, but FFMI showed no correlation. Both male and female, FVC and FEV₁ had a negative correlation with WHR (male, FVC r=-0.327, FEV₁ r=-0.36; p<0.05; female, FVC r=-0.175, FEV₁ r=-0.213; p<0.05). In a multiple linear regression of considering the body composition of the total group, FVC explained FFM, BMI, and FFMI in order (r²=0.579, 0.657, 0.663). FEV₁ was explained only fat% (r²=0.011), and FEF_25-75 was explained muscle mass, FFMI, FFM (r²=0.126, 0.138, 0.148).

Conclusion

The BMI, fat%, muscle mass, FFM, FFMI, WHR have significant association with pulmonary function but r² (adjusted coefficient of determination) were not high enough for explaining lung function.

Longitudinal associations of adiposity with adult lung function in the Childhood Determinants of Adult Health (CDAH) study

Childhood BMI has been reported to be positively associated with adult lung function. The aim of this study was to investigate the effect of childhood BMI on young adult lung function independently of the effects of lean body mass (LBM). Clinical and questionnaire data were collected from 654 young Australian adults (aged 27-36 years), first studied when age 9, 12, or 15 years. Adult lung function was measured by forced vital capacity (FVC), forced expiratory volume in 1 s (FEV(1)), FEV(1)/FVC ratio, and the forced expiratory flow in the middle 50% of FVC (FEF(25-75)). BMI and LBM were derived from anthropometric measures at baseline (1985) and at follow-up (2004-2006). Multivariable models were used to investigate the effect of age and sex standardized BMI in childhood on adult lung function, before and after adjustment for LBM. Adult adiposity had a strong deleterious effect on lung function, irrespective of childhood BMI, and adjustment for childhood LBM eliminated any apparent beneficial effect of childhood BMI on adult FEV(1) or FVC. This suggests that the beneficial effect of increased BMI in childhood on adult FEV(1) and FVC observed in previous longitudinal studies is likely to be attributable to greater childhood LBM not adiposity. Obese children who become obese adults can expect to have poorer lung function than those who maintain healthy weight but large deficits in lung function are also likely for healthy weight children who become obese adults. This highlights the importance of lifetime healthy weight maintenance.

Cross-sectional analysis of the utility of pulmonary function tests in predicting emphysema in ever-smokers

Emphysema is largely an under-diagnosed medical condition that can exist in smokers in the absence of airway obstruction. We aimed to determine the sensitivity and specificity of pulmonary function tests (PFTs) in assessing emphysema using quantitative CT scans as the reference standard. We enrolled 224 ever-smokers (current or former) over the age of 40. CT of thorax was used to quantify the low attenuation area (% emphysema), and to measure the standardized airway wall thickness. PFTs were used individually and in combination to predict their ability to discriminate radiographic emphysema. Significant emphysema (>7%) was detected in 122 (54%) subjects. Twenty six (21%) emphysema subjects had no evidence of airflow obstruction (FEV(1)/FVC ratio <70%), while all subjects with >23% emphysema showed airflow obstruction. The sensitivity and specificity of spirometry for detecting radiographic emphysema were 79% and 75%, respectively. Standardized airway wall thickness was increased in subjects with airflow obstruction, but did not correlate with emphysema severity. In this cohort of lifetime ever-smokers, PFTs alone were inadequate for diagnosing emphysema. Airway wall thickness quantified by CT morphometry was associated with airflow limitation, but not with emphysema indicating that the heterogeneous nature of lung disease in smokers may represent distinct phenotypes.

Effects of body composition and adipose tissue distribution on respiratory function in elderly men and women: the health, aging, and body composition study

BACKGROUND

Previous cross-sectional studies demonstrate positive associations of fat-free mass and negative associations of centrally distributed fat deposits with respiratory function in older adults. Few studies have evaluated whether greater losses of muscle and increases in fat are associated with more rapid decline in respiratory function in aging.

METHODS

Nine hundred and fifty-seven men and 1,024 women aged, respectively, 73.6 ± 2.8 years and 73.2 ± 2.8 years at baseline were followed for 5 years. Body weight, waist circumference, bone mineral density, fat-free mass, fat mass and fat mass percentage as measured by DXA, abdominal subcutaneous and visceral adipose tissue, thigh muscle area, thigh intermuscular fat by CT and forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) were evaluated at baseline and after 5-years follow-up.

RESULTS

Cross-sectional analyses showed that height and thigh muscle area were positively and visceral adipose tissue negatively related to FEV1 and FVC. Increase in fat mass over five years was associated with concurrent FEV1 and FVC decline. In analyses stratified by weight-change categories, men and women who gained weight (vs stable/lost weight) had more rapid declines in FEV1 and FVC.

CONCLUSION

In this well-functioning cohort, less muscle and greater abdominal fat were each associated with poorer lung spirometry cross-sectionally, whereas increase in fat mass over 5 years was associated with concurrent FEV1 and FVC decline. Weight gain and accompanying fat deposition may accelerate age-related declines in respiratory function.

Physiologically interpretable prediction equations for spirometric indexes

The need for ethnic-specific reference values of lung function variables (LFs) is acknowledged. Their estimation requires expensive and laborious examinations, and therefore additional use of results in physiology and epidemiology would be profitable. To this end, we proposed a form of prediction equations with physiologically interpretable coefficients: a baseline, the onset age (A0) and rate (S) of LF decline, and a height coefficient. The form was tested with data from healthy, nonsmoking Poles aged 18–85 yr (1,120 men, 1,625 women) who performed spirometry maneuvers according to American Thoracic Society criteria. The values of all the coefficients (also A0) for several LFs were determined with regression of LF on patient's age and deviation of patient's height from the mean height in the year group of this patient. S values for forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), peak expiratory flow, and maximal expiratory flow at 75% of FVC (MEF75) were very similar in both sexes (1.03 ± 0.07%/yr). FEV1/FVC declines four to five times slower. S for MEF25 appeared age dependent. A0 was smallest (28–32 yr) for MEF25 and FEV1. About 50% of each age subgroup (18–40, 41–60, 61–85 yr) exhibited LFs below the mean, and 4–6% were below the 5th percentile lower limits of normal, and thus the form of equations proposed in the paper appeared appropriate for spirometry. Additionally, if this form is accepted, epidemiological and physiological comparison of different LFs and populations will be possible by means of direct comparison of the equation coefficients.

Measurement of lung volumes

Lung volume measurements always determine total lung capacity (TLC), and most measurement techniques also determine functional residual capacity (FRC) and residual volume (RV). These measurements are needed less often than spirometry-derived values and require somewhat more difficult methods than required by spirometry. As with spirometry, accurate interpretation relies on appropriate reference values, standardized methodology and technically well-performed testing. A reduction in TLC defines chest restriction. Increases in TLC, FRC and RV are often seen in patients with airway obstruction. Patients with mixed restrictive and obstructive disease may have spirometry results that are difficult to interpret, and it is in these patients that lung volume measurements may be especially helpful.

Determinants of lung volumes in chronic spinal cord injury

OBJECTIVE

To characterize determinants of lung volumes in chronic spinal cord injury (SCI).

DESIGN

Cross-sectional.

SETTING

VA Boston Healthcare System.

PARTICIPANTS

White men (N=330) with chronic SCI.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Questionnaire responses and measurements of lung volumes.

RESULTS

Adjusted for SCI severity and stature, greater body mass index (BMI) was associated (all P<.05) with lower total lung capacity (TLC) (-38.7 mL x kg(-1) x m(-2)), functional residual capacity (FRC) (-73.9 mL x kg(-1) x m(-2)), residual volume (RV) (-40.4 mL x kg(-1) x m(-2)), and expiratory reserve volume (ERV) (-32.2 mL x kg(-1) x m(-2)). The effect of BMI on RV was most pronounced in quadriplegia (-72 mL x kg(-1) x m(-2)). Lifetime smoking was associated with a greater FRC (5.3 mL/pack-year) and RV (3.1 mL/pack-years). The effects of lifetime smoking were also greatest in quadriplegia (11 mL/pack-year for FRC; 7.8 mL/pack-year for RV). Time since injury, independent of age, was associated with a decrease in TLC, FRC, ERV, and RV (P<.05). Age was not a predictor of TLC once time since injury was considered.

CONCLUSIONS

Determinants of FRC, TLC, ERV, and RV in chronic SCI include factors related and unrelated to SCI. The mechanisms remain to be determined but likely involve the elastic properties and muscle function of the respiratory system and perhaps the effects of systemic inflammation related to adiposity. Addressing modifiable factors such as obesity, muscle stiffness, and smoking may improve respiratory morbidity and mortality in SCI by improving pulmonary function.

Obesity and asthma: a specific phenotype?

BACKGROUND

Obesity is associated with an increased prevalence of asthma, especially in women, and appears to be more severe in the obese. This study aimed to determine if obese subjects have a specific asthma phenotype.

METHODS

Forty-four consecutive obese subjects (body mass index [BMI] > or = 30 kg/m(2)) and 44 consecutive nonobese subjects (BMI < 25 kg/m(2)), all with asthma, completed an asthma control questionnaire, and underwent methacholine challenge with symptom perception scores, and sputum induction for differential cell count. BMI, waist circumference, and waist-to-hip ratio also were measured.

RESULTS

Despite similar expiratory flows, bronchodilator response, airway responsiveness to methacholine, and symptom perception scores, asthma control was poorer in obese subjects than in nonobese subjects (p = 0.005). Total lung capacity (p = 0.01), expiratory reserve volume (p < 0.0001), functional residual capacity (p < 0.0001), and residual volume (p = 0.006) were lower in obese subjects than in nonobese subjects. Induced-sputum eosinophil and neutrophil counts were similar in both groups, although there was an inverse correlation between sputum eosinophils and waist circumference and a trend for a similar relationship for BMI. Blood serum C-reactive protein (p = 0.009) and fibrinogen (p = 0.0004) levels were higher in obese subjects than in nonobese subjects.

CONCLUSION

Obese people with asthma had poorer asthma control than nonobese asthmatics despite similar symptoms perception. Bronchial and systemic inflammatory characteristics and the specific pattern of pulmonary function changes suggest a different phenotype of asthma in these subjects.

TRIAL REGISTRATION

Clinicaltrials.gov Identifier: NCT00532363 and NCT00532831.

Longitudinal association of body mass index with lung function: the CARDIA study

Background

Lung function at the end of life depends on its peak and subsequent decline. Because obesity is epidemic in young adulthood, we quantified age-related changes in lung function relative to body mass index (BMI).

Methods

The Coronary Artery Risk Development in Young Adults (CARDIA) study in 1985–86 (year 0) recruited 5,115 black and white men and women, aged 18–30. Spirometry testing was conducted at years 0, 2, 5 and 10. We estimated 10 year change in FVC, FEV₁ and FEV₁/FVC according to baseline BMI and change in BMI within birth cohorts with initial average ages 20, 24, and 28 years, controlling for race, sex, smoking, asthma, physical activity, and alcohol consumption.

Measurements and Main Results

Participants with baseline BMI < 21.3 kg/m² experienced 10 year increases of 71 ml in FVC and 60 ml in FEV₁ and neither measure declined through age 38. In contrast, participants with baseline BMI ≥ 26.4 kg/m² experienced 10 year decreases of 185 ml in FVC and 64 ml in FEV₁. FEV₁/FVC increased with increasing BMI. Weight gain was also associated with lung function. Those who gained the most weight over 10 years had the largest decrease in FVC, but FVC increased with weight gain in those initially thinnest. In contrast, FEV₁ decreased with increasing weight gain in all participants, with maximum decline in obese individuals who gained the most weight during the study.

Conclusion

Among healthy young adults, increasing BMI in the initially thin participants was associated with increasing then stable lung function through age 38, but there were substantial lung function losses with higher and increasing fatness. These results suggest that the obesity epidemic threatens the lung health of the general population.

Ethnic differences in adolescent lung function: anthropometric, socioeconomic, and psychosocial factors

RATIONALE

The relative contribution of body proportion and social exposures to ethnic differences in lung function has not previously been reported in the United Kingdom.

OBJECTIVES

To examine ethnic differences in lung function in relation to anthropometry and social and psychosocial factors in early adolescence.

METHODS

The subjects of this study were 3,924 pupils aged 11 to 13 years, of whom 80% were ethnic minorities with satisfactory lung function measures. Data were collected on economic disadvantage, psychological well-being, tobacco exposure, height, FEV(1), and FVC.

MEASUREMENTS AND MAIN RESULTS

The lowest FEV(1) was observed for Black Caribbean/African children after adjusting for standing height (SH) (white boys: 2.475 L; 95% confidence interval [CI], 2.442-2.509; white girls: 2.449 L; 95% CI, 2.464-2.535]; Black Caribbean boys: -14% [95% CI, -16 to -12]; Black Caribbean girls: -13% [95% CI, -16 to -11]; Black African boys: -15% [95% CI, -17 to -13]; Black African girls: -17% [95% CI, -19 to -14]; Indian boys: -13% [95% CI, -16 to -11]; Indian girls: -11% [95% CI, -14 to -8]; Pakistani/Bangladeshi boys: -7% [95% CI, -9 to -5]; Pakistani/Bangladeshi girls: -9% [95% CI, -11 to -6]). Adjustment for upper body segment instead of SH achieved a further reduction in ethnic differences of 41 to 51% for children of Black African origin and 26 to 39% for the other groups. Overcrowding (boys) and poor psychological well-being (boys and girls) were independent correlates of FEV(1), explaining up to a further 10% of ethnic differences. Similar patterns were observed for FVC. Social exposures were also related to height components.

CONCLUSIONS

Differences in upper body segment explained more of the ethnic differences in lung function than SH, particularly among Black Caribbeans/African subjects. Social correlates had a smaller but significant impact. Future research needs to consider how differential development of lung capacity is compromised by the social patterning of growth trajectories.

Relationship between body composition and lung function in elderly men and women

INTRODUCTION

The purpose of this study was to evaluate the relationship between body composition parameters and lung functions including vital capacity (VC), forced vital capacity (FVC), forced expiratory volume in 1 second (FEV(1)), FEV(1):VC ratio, and FEV(1):FVC ratio in elderly men and women.

METHODS

The study was a cross-sectional evaluation of 99 healthy men and women (aged 60-88 years). Anthropometric and body composition parameters (including fat mass [FM], fat-free mass [FFM] and percentage body fat [%BF]) were evaluated using the skinfold method, and lung function was examined using spirometry.

RESULTS

Data analysis showed %BF, body FM and body mass index (BMI) of women to be significantly higher than men. Also, their body FFM was significantly less than men (P<0.05). Lung volume (P<0.01) and lung capacity values (P<0.05) (VC, FVC, FEV(1), FEV(1):VC, FEV(1):FVC) of women were significantly less than men. There was a positive significant relationship between the FFM versus FVC and FEV(1) values of women and men. A negative significant relationship was demonstrated between body FM, BMI and FVC of all subjects.

CONCLUSION

This investigation showed that women aged between 60 and 88 years had a lower lung capacity compared to men of the same age. Older women were found to have a higher body fat ratio than men, and it was found that increasing %BF and BMI had a negative effect on lung functions in both sexes.

Pulmonary ventilatory functions and obesity in Kuwait

OBJECTIVE

To study the relationship between obesity and pulmonary ventilatory functions in Kuwaiti adults.

SUBJECTS AND METHODS

A total of 200 male and 180 female Kuwaiti adults aged 20-65 years were investigated in six medical centers from April 2004 to March 2006. Parameters measured included forced expiratory volume in 1 s (FEV(1)), forced vital capacity (FVC), FEV(1) as a percentage of FVC (FEV%); body mass index (BMI in kg/m(2)) and waist-to-hip ratio (W/H).

RESULTS

For the whole group, males or females, BMI (kg x m(2)) and W/H were poor individual predictors of pulmonary ventilatory functions. However, central adiposity (W/H) was associated with restrictive respiratory impairment (10.6-13.9% decrease in FEV(1) and 10-12.3% decrease in FVC), independent of sex, age or height. In obese females and males (BMI >30), increasing severity of obesity was significantly (p < 0.05, R(2) >0.6) [corrected] associated with increasing restrictive respiratory impairment (8.7-14.4% decrease in FEV(1) and 8-11.7% decrease in FVC), with no evidence of obstructive disease (FEV(1)/FVC >0.8).

CONCLUSION

In adult Kuwaiti males and females, increase in body fat at BMI >30 or W/H >1 was associated with a restrictive effect on pulmonary ventilation.

Truncal adiposity and lung function in older black women

The increase in adiposity associated with aging is a concern in older adults, especially as it relates to the risk for ventilatory complications. Therefore, the specific aim of this study was to determine the association of various measures of abdominal adiposity with lung function in a sample of older healthy black women. Participants (n=27) had no history of diabetes or respiratory disease. The mean age was 67 years. Lung function was measured by spirometry using percent of predicted values for forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1). Body fat was measured using a three-dimensional photonic scanner and dual energy X-ray absorptiometry (DXA). Correlation analyses show that percent body fat in the trunk (%TF) is significantly associated with percent predicted FVC (r=-0.38; p<0.05). No association was observed between anthropometric indices of truncal adiposity and lung function. Results of this study show that truncal fat mass measured by DXA is more strongly associated with lung function than anthropometric indices of truncal adiposity in this sample of women.

Body composition and respiratory function in healthy non-obese children

BACKGROUND

The purpose of the present paper was to evaluate the role that body composition plays in lung function, among healthy children and adolescents.

METHODS

Cross-sectional study was undertaken using sex- and age-stratified sampling among healthy children and adolescents aged 6-18 years. Spirometry was performed on every child who fulfilled inclusion criteria. Fat mass (FM) and fat-free mass (FFM) were calculated from triceps skinfold thickness and arm circumference. Multiple logistic regression was used to obtain adjusted prevalence odds ratios (OR) and 95% confidence intervals (95%CI) between low pulmonary function (PF) of schoolchildren and body composition expressed in FM and FFM. Calculations of OR imply that the outcome is dichotomous (low PF/normal PF), therefore those children who had parameters of pulmonary function below the 25th percentile were classed as cases and the rest of the subjects were considered as controls.

RESULTS

A total of 2408 children were included; 1270 (53%) of them were male and 1138 (47%), female. Among boys the increase of FFM was associated with an increase of forced expiratory volume in 1 s (FEV1). Among girls the increase of FFM was associated with an increase of FEV1, forced vital capacity, and peak expiratory flow. The increase in FM was associated with a decrease of spirometric parameters in both genders, with a stronger effect among boys.

CONCLUSIONS

The present study confirms the negative effect of body fat on the PF of children and adolescents, even though obese subjects were excluded. The effect is different between boys and girls.

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.

Changes in thoracic gas volume with air-displacement plethysmography after a weight loss program in overweight and obese women

OBJECTIVE

This study was designed to compare measured and predicted thoracic gas volume (V (TG)) after weight loss and to analyze the effect of body composition confounders such as waist circumference (WC) on measured V (TG) changes.

DESIGN

Prospective intervention study.

SETTING

Outpatient University Laboratory, Lisbon, Portugal.

SUBJECTS

Eighty-five overweight and obese women (body mass index = 30.0+/-3.5 kg/m(2); age = 39.0+/-5.7 years) participating in a 16-month university-based weight control program designed to increase physical activity and improve diet.

METHODS

Body weight (Wb), body volume (Vb), body density (Db), fat mass (FM), percent fat mass (%FM) and fat-free mass (FFM) were assessed by air-displacement plethysmography (ADP) at baseline and at post-intervention (16 months). The ADP assessment included a protocol to measure V (TG) and a software-based predicted V (TG). Dual-energy X-ray absorptiometry (DXA) (Hologic QDR 1500) was also used to estimate FM, %FM and FFM. Maximal oxygen uptake (VO(2) max) was assessed with a modified Balke cardiopulmonary exercise testing protocol with a breath-by-breath gas analysis.

RESULTS

Significant differences between the baseline and post-weight loss intervention were observed for body weight and composition (Vb, Db, %FM, FM and FFM), and measures of V (TG) (measured: Delta=0.2 l, P<0.001; predicted: Delta=0.01 l, P<0.010) variables. Measured V (TG) change was negatively associated with the change in the WC (P=0.008), controlling for VO(2) max and age (P=0.007, P=0.511 and P=0.331). Linear regression analysis results indicated that %FM and FM using the measured and predicted V (TG) explained 72 and 76%, and 86 and 90% respectively, of the variance in %FM and FM changes using dual-energy x-ray absorptiometry.

CONCLUSIONS

After weight loss, measured V (TG) increased significantly, which was partially attributed to changes is an indicator of body fat distribution such as WC. Consequently, measured and predicted V (TG) should not be used interchangeably when tracking changes in body composition. The mechanisms relating the reduction of an upper body fat distribution with an increase measured V (TG) are worthy of future investigation.

Modelling the lung function of Caucasians during adolescence as a basis for reference values

BACKGROUND

In childhood the relationship between lung size and stature changes during the adolescent growth spurt. This is not allowed for in models of lung function based on stature alone. For spirometric indices inclusion of an age x stature interaction (A x St) can overcome the difficulty.

AIM

The study tested the hypothesis that this simple, interactive model might also be effective for total lung capacity and its subdivisions and the single breath transfer factor for carbon monoxide.

SUBJECTS AND METHODS

Data were available for 695 asymptomatic non-smokers (Caucasians) aged 7-20 years (440 boys, 255 girls). Each lung function index was described using the above model and the fit was compared with that from a linear, power or polynomial model based on stature alone.

RESULTS

After allowing for stature, the A x St interaction term was significant for almost all indices. The improved fit was most apparent for the lung function of older adolescent boys. Reference values using the model are reported.

CONCLUSIONS

A simple model based on stature and an interaction between stature and age can account for the changing relationship between body habitus during the growth spurt and lung size and transfer factor in a single equation encompassing children and adolescents. Its use is recommended for deriving reference values when the explanatory variables are limited to stature and age.

Body fat distribution, body composition, and respiratory function in elderly men

BACKGROUND

Most population studies have reported weak or nonsignificant associations between body mass index (BMI; in kg/m2) and lung function.

OBJECTIVE

This study focused on the distinct effects of fat distribution and body composition on lung function and examined these relations in elderly men.

DESIGN

The study was a cross-sectional evaluation of 2744 men aged 60-79 y who were free of cardiovascular disease and cancer and were drawn from general practices in 24 British towns. Anthropometric and body-composition [including fat mass (FM), fat-free mass (FFM), and percentage body fat (%BF) evaluated with bioelectric impedance] measurements were made, and lung function was examined by using spirometry.

RESULTS

Height-standardized forced expiratory volume in 1 s (FEV1) was diminished only in lean (BMI < 22.5) and obese (BMI > or = 30) men, but forced vital capacity (FVC) tended to decrease with increasing BMI (P < 0.01). All other measures of adiposity [ie, waist circumference (WC), waist-hip ratio (WHR), FM, and %BF] were significantly and inversely related to FEV1 and FVC after adjustment for confounders, including age and cigarette smoking (all: P < 0.05). This was seen both in nonobese (BMI < 30) and obese men. FFM was positively associated with FEV1 (P = 0.03) and to a lesser extent with FVC. Higher BMI and FFM were both associated with reduced odds of a low FEV1-FVC ratio (ie, <70%).

CONCLUSION

Total body fat and central adiposity are inversely associated with lung function, but increased FFM reflecting increases in muscle mass is associated with increased lung function and lower odds of low FEV1:FVC in the elderly.

Pulmonary function of herdsmen

OBJECTIVE

To determine whether the pulmonary function deficit documented previously in Fulani children is also present in adult Fulani herdsmen in northern Nigeria.

SUBJECTS AND METHODS

The subjects for this study consisted of adult Fulani men from the hamlet of Magama Gumau and adult non-Fulani men from the city of Jos. Age, height, weight, mid-arm circumference (MAC), triceps skin-fold thickness, forced vital capacity (FVC), forced expiratory volume in one second (FEV1), forced expiratory flow during the middle half of the FVC maneuver (FEF25-75%), and peak expiratory flow rate (PEF) were measured. Body mass index (BMI) and FEV1/FVC were calculated for all subjects. Multiple regression analysis was performed to identify correlations between pulmonary function parameters and anthropometric variables.

RESULTS

The 44 Fulani subjects and 28 urban subjects were well-matched for age and height. The Fulani men weighed significantly less than the urban men (58.5+/-9.4 versus 67.4+/-11.3 kg, p <0.001) and consequently had significantly lower BMI, MAC, and triceps skin-fold thickness. The only significant difference in pulmonary function parameters between the two groups was in FEV1/FVC (0.93+/-0.1 versus 0.85+/-0.1, p <0.001). Small but significant correlations were found between pulmonary function parameters and anthropometric variables for both study populations.

CONCLUSIONS

The pulmonary function deficits documented previously in Fulani children and adolescents were not present in adult Fulani men. However, the observed elevation in FEV1/FVC in the rural Fulani men as compared to their urban counterparts, which is often seen in restrictive pulmonary patterns, deserves further study.