Pulmonary function in adults with recent and former asthma and the role of sex and atopy

Association between abdominal obesity and pulmonary function in apparently healthy adults: A systematic review

BACKGROUND

Obesity, especially abdominal obesity as a chronic disorder is associated with a high risk of developing non-communicable diseases such as respiratory diseases. Impaired lung function is a sign of early respiratory injury. This review summarizes the current knowledge of the effects of abdominal obesity on pulmonary function in apparently healthy adults.

METHODS

Google Scholar, PubMed, Science Direct, and Scopus databases were searched from 2014 up to August 2020 using relevant keywords. All original articles written in English evaluating the effects of abdominal obesity on pulmonary function in apparently healthy adults were eligible for this review.

RESULTS

A total of 26 studies (23 cross-sectional and three cohort) involving 68,024 participants were included in this review. More than 88% of the included studies reported that abdominal obesity significantly inversely was associated with pulmonary function.

CONCLUSION

The findings indicate that in subjects with abdominal obesity respiratory function decline possibly due to mechanical compression and obesity-induced airway inflammation. Therefore, nutrition and lifestyle interventions are required for the reduction of abdominal obesity that leads to improving pulmonary function and metabolic disease.

Association between CT-Measured Abdominal Skeletal Muscle Mass and Pulmonary Function

A relationship between lung function and sarcopenia has been suggested. This study aimed to evaluate the association between lung function and abdominal skeletal muscle mass, as measured by computed tomography (CT). The clinical records of 1907 subjects (1406 males, mean age 53.1 ± 9.2 years), who underwent routine health check-ups, including spirometry and abdominal CT, were retrospectively reviewed. The CT-measured skeletal muscle index (SMI_CT, cm²/(kg/m²) was defined as the skeletal muscle area of the third lumbar vertebrae (L3) level that is normalized by the body mass index. The mean values of forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) gradually increased as the SMI_CT quartiles increased (all p for trend < 0.05). The proportions of subjects with less than 80% of the predicted FVC (%) and predicted FEV1 (%) significantly decreased as the SMI_CT quartiles increased (all p for trend < 0.05). The β regression coefficients for FVC and FEV1 significantly increased as the SMI_CT quartiles increased after adjusting for other confounding variables (p for trend < 0.05). This study showed that abdominal muscle mass, which was precisely measured by CT, independently affected lung function proportionally after adjusting for confounding factors in relatively healthy adults.

The longitudinal association between changes in lung function and changes in abdominal visceral obesity in Korean non-smokers

Obesity, particularly abdominal obesity, might be related to decreased lung function. We aimed to investigate whether obesity indices are associated with forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) in asymptomatic non-smokers through a longitudinal cohort study. The clinical records of 1,145 subjects (428 males, mean age 52.3 years) who underwent a comprehensive health evaluation, including spirometry and abdominal fat computed tomography, at least twice between 2007 and 2014 were retrospectively reviewed and analysed. The mean follow-up period was 1,105 days (over 3.0 years). The baseline total adipose tissue (TAT) and visceral adipose tissue (VAT) were inversely associated with both FEV1 and FVC (P < 0.05). The longitudinal study found that increasing TAT and VAT were significantly related to decreasing FEV1 and FVC, whereas decreasing TAT and VAT were related to increasing FEV1 and FVC in both males and females (P < 0.05). The strength and consistency of these associations were clearer in males than in females. However, no significant relationship was found between changes in subcutaneous adipose tissue and changes in lung function. In Korean non-smokers, longitudinal changes in abdominal visceral fat were found to be inversely related to changes in lung function over a mean period of three years. These results suggest that decreasing abdominal visceral obesity could increase lung function despite ageing.

Gender differences in effects of obesity and asthma on adolescent lung function: Results from a population-based study

OBJECTIVE

To investigate lung function associated with asthma and body mass index (BMI) among adolescents at 96 northern Taiwan junior high schools participating in an asthma screening program.

METHODS

The questionnaires and lung function test results measured for 3669 boys and 3523 girls were included in this study for data analysis. Measures of forced vital capacity (FVC), forced expiratory volume in 1 second (FEV₁) and FEV₁/FVC ratio were compared by sex, asthma status and BMI.

RESULTS

Overall mean FVC levels were similar between students with and without asthma, 3.71 L vs. 3.71 L for boys (p = 0.991) and 2.79 vs. 2.78 for girls (p = 0.517). The overall mean FEV₁ levels were also similar between girls with and without asthma. Asthmatic boys had lower FEV₁ than non-asthmatic boys. Mean FEV₁/FVC was significantly lower in students with asthma than those without asthma. Mean FVC and FEV₁ increased with BMI in both sexes. A lower mean FEV₁/FVC was observed among students with asthma and high BMI, and was more pronounced in boys than in girls. Multivariable regression analysis also showed that FEV₁/FVC ratios were negatively associated with asthma and high BMI, stronger in boys than in girls for asthma (β = -2.176 (standard errors (SE) = 0.268) vs. -1.085 (SE = 0.258) and for BMI (β = -0.309 (SE = 0.025) vs. -0.218 (SE = 0.029)).

CONCLUSION

This northern Taiwan study suggests that FEV₁/FVC is negatively associated with asthma and high BMI in adolescents, stronger for boys than for girls.

The longitudinal relationship of changes of adiposity to changes in pulmonary function and risk of asthma in a general adult population

BACKGROUND

Adiposity has been linked to both higher risk of asthma and reduced lung function. The effects of adiposity on asthma may depend on both atopic status and gender, while the relationship is less clear with respect to lung function. This study aimed to explore longitudinal weight changes to changes in forced expiratory volume in first second (FEV1) and forced vital capacity (FVC), as well as to incident cases of asthma and wheezing, according to atopy and gender.

METHODS

A general population sample aged 19-72 years was examined with the same methodology five years apart. Longitudinal changes in weight, body mass index, waist circumference, and fat percentage (bio-impedance) were analyzed with respect to changes of FEV1 and FVC (spirometry), and incidence of asthma and wheezing (questionnaire). Gender, atopy (serum specific IgE-positivity to inhalant allergens) and adipose tissue mass prior to adiposity changes were examined as potential effect modifiers.

RESULTS

A total of 2,308 persons participated in both baseline and five-year follow-up examinations. Over the entire span of adiposity changes, adiposity gain was associated with decreasing levels of lung function, whereas adiposity loss was associated with increasing levels of lung function. All associations were dependent on gender (p-interactions < 0.0001). For one standard deviation weight gain or weight loss, FEV1 changed with (+/-)72 ml (66-78 ml) and FVC with (+/-)103 ml (94-112 ml) in males. In females FEV1 changed with (+/-) 27 ml (22-32 ml) and FVC with (+/-) 36 ml (28-44 ml). There were no changes in the FEV1/FVC-ratio. The effect of adiposity changes increased with the level of adipose tissue mass at the start of the study (baseline), thus, indicating an aggregate effect of the total adipose tissue mass. Atopy did not modify these associations. There were no statistically significant associations between changes in adiposity measures and risk of incident asthma or wheeze.

CONCLUSIONS

Over a five-year period, increasing adiposity was associated with decreasing lung function, whereas decreasing adiposity was associated with increasing lung function. This effect was significantly greater in males than in females and increased with pre-existing adiposity, but was independent of atopy.

Serum 25-hydroxyvitamin D levels and lung function in adults with asthma: the HUNT Study

The association between vitamin D status and lung function in adults with asthma remains unclear. We studied this cross-sectional association and possible modification by sex and allergic rhinitis in 760 adults (aged 19-55 years) with self-reported asthma in the Nord-Trøndelag Health Study. Serum 25-hydroxyvitamin D (25(OH)D) level <50 nmol·L(-1) was considered deficient. Lung function measurements included forced expiratory volume in 1 s (FEV1) % predicted, forced vital capacity (FVC) % predicted and FEV1/FVC ratio. Multiple linear regression models were used to estimate adjusted regression coefficients (β) and 95% confidence intervals. 44% of asthma adults had serum 25(OH)D levels <50 nmol·L(-1). Its associations with lung function measures seemed to be modified by sex and allergic rhinitis (p<0.03 for three-way interaction term). Overall, a serum 25(OH)D level <50 nmol·L(-1) was not associated with lung function measurements in subjects with allergic rhinitis in this asthma cohort. In men with asthma but without allergic rhinitis, however, a serum 25(OH)D level <50 nmol·L(-1) was significantly associated with lower FEV1/FVC ratio (β=-8.60%; 95% CI: -16.95%- -0.25%). Low serum 25(OH)D level was not associated with airway obstruction in most asthma adults with the exception of men with asthma but without allergic rhinitis.