Respiratory symptoms and respiratory deaths: A multi-cohort study with 45 years observation time

Association between body mass index and respiratory symptoms in US adults: a national cross-sectional study

The correlation between body mass index (BMI) and the development of cough, shortness of breath, and dyspnea is unclear. Therefore, this study aimed to investigate the association between these parameters. Data from individuals who participated in the National Health and Nutrition Examination Survey between 2003 and 2012 were analyzed. Weighted logistic regression analysis and smoothed curve fitting were used to examine the correlation between BMI and respiratory symptoms. In addition, the relationship between BMI, chronic obstructive pulmonary disease (COPD), and bronchial asthma was examined. Stratified analysis was used to discover inflection points and specific groups. Weighted logistic regression and smoothed curve fitting revealed a U-shaped relationship between BMI and respiratory symptoms. The U-shaped relationship in BMI was also observed in patients with bronchial asthma and COPD. Stratified analysis showed that the correlation between BMI and wheezing and dyspnea was influenced by race. In addition, non-Hispanic black individuals had a higher risk of developing cough than individuals of the other three races [OR 1.040 (1.021, 1.060), p < 0.0001], and they also exhibited an inverted U-shaped relationship between BMI and bronchial asthma. However, the association of BMI with cough, wheezing, dyspnea, COPD, and asthma was not affected by sex. High or low BMI was associated with cough, shortness of breath, and dyspnea, and has been linked to bronchial asthma and COPD. These findings provide new insights into the management of respiratory symptoms and respiratory diseases.

Correlation between serum iron levels and pulmonary function: A cross-sectional analysis based on NHANES database 5319 cases

Pulmonary function, one of the main indicators of respiratory system assessment, is difficult to measure in specific cases. The study investigated the association between serum iron levels and pulmonary function. The cross-sectional study was conducted using data from 5319 participants from the 2010-2012 National Health and Nutrition Examination Survey. Forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), and forced expiratory flow from 25% to 75% of FVC were used as indicators of pulmonary function to analyze the relationship of serum iron and pulmonary function. Univariate and stratified analyses, multiple equation regression analysis, smoothed curve fitting analysis, and threshold effect analysis were performed to explore the relationship between pulmonary function and serum iron concentrations. Threshold effect analysis revealed a nonlinear relationship between serum iron levels and FVC, as well as FEV1, with inflection points observed at 8.1 (µmol/L) and 8.4 (µmol/L), respectively. When serum iron concentrations fell below the inflection point, there was no statistically significant relationship between serum iron and FVC (P = .065) or FEV1 (P = .095) (P > .005). However, when serum iron concentrations exceeded the inflection point, both FVC (β = 6.87; 95% confidence interval [CI] = 3.95, 9.79; P < .0001) and FEV1 (β = 7.09; 95% CI = 4.54, 9.64; P < .0001) exhibited a positive correlation with increasing serum iron levels. Additionally, forced expiratory flow from 25% to 75% of FVC (mL/s) demonstrated a positive association with serum iron (β = 6.72; 95% CI = 2.30, 11.13; P = .0029). Serum iron level was positively correlated with pulmonary function within a certain range of serum iron concentration. Serum iron level may be a protective factor for pulmonary function.

The association between sleep duration, respiratory symptoms, asthma, and COPD in adults

Introduction

The association between sleep duration and cough, wheezing, and dyspnea was unclear. This research aimed to test this relationship.

Methods

Research data were obtained from people who participated in the National Health and Nutrition Examination Survey (NHANES) from 2005 to 2012. We used weighted logistic regression analysis and fitted curves to explore the association between sleep and respiratory symptoms. In addition, we investigated the association between sleep duration, chronic obstructive pulmonary disease (COPD), and asthma. The stratified analysis is used to analyze inflection points and specific populations.

Results

The 14,742 subjects are weighted to reflect the 45,678,491 population across the United States. Weighted logistic regression and fitted curves show a U-shaped relationship between sleep duration and cough and dyspnea. This U-shaped relationship remained in people without COPD and asthma. The stratified analysis confirmed that sleep duration before 7.5 h was negatively associated with cough (HR 0.80, 95% CI 0.73-0.87) and dyspnea (HR 0.82, 95% CI 0.77-0.88). In contrast, it was positively associated with cough and (HR 1.30, 95% CI 1.14-1.48) dyspnea (HR 1.12, 95% CI 1.00-1.26) when sleep duration was >7.5 h. In addition, short sleep duration is associated with wheezing, asthma, and COPD.

Conclusion

Both long and short sleep duration are associated with cough and dyspnea. And short sleep duration is also an independent risk factor for wheezing, asthma, and COPD. This finding provides new insights into the management of respiratory symptoms and diseases.

Respiratory symptoms and cardiovascular causes of deaths: A population-based study with 45 years of follow-up

This study determined the association between respiratory symptoms and death from cardiovascular (CV) diseases during 45 years in a pooled sample of four cohorts of random samples of the Norwegian population with 95,704 participants. Respiratory symptoms were assessed using a modification of the MRC questionnaire on chronic bronchitis. We analyzed the association between respiratory symptoms and specific cardiovascular deaths by using Cox regression analysis with age as the time variable, accounting for cluster-specific random effects using shared frailty for study cohort. Hazard ratios (HR) for death were adjusted for sex, highest attained education, smoking habits, occupational air pollution, and birth cohort. Overall, 12,491 (13%) of participants died from CV diseases: 4,123 (33%) acute myocardial infarction, 2,326 (18%) other ischemic heart disease, 2,246 (18%) other heart diseases, 2,553 (20%) cerebrovascular diseases, and 1,120 (9%) other vascular diseases. The adjusted HR (95% confidence interval) for CV deaths was 1.9 (1.7–2.1) in men and 1.5 (1.2–1.9) in women for “yes” to the question “Are you breathless when you walk on level ground at an ordinary pace?”. The same item response showed an adjusted HR for death from acute myocardial infarction of 1.8 (1.5–2.1), other ischemic heart disease 2.2 (1.8–2.7), other heart diseases 1.5 (1.1–1.9), cerebrovascular disease 1.8 (1.5–2.3), and other circulatory diseases 1.7 (1.2–2.4). The adjusted HR for CV death was 1.3 (1.2–1.4) when answering positive to the question” Are you more breathless than people of your own age when walking uphill?”. However, positive answers to questions on cough, phlegm, wheezing and attacks of breathlessness were after adjustments not associated with early CV deaths. The associations between CV deaths and breathlessness were also present in never smokers. Self-reported breathlessness was associated with CV deaths and could be an early marker of CV deaths.