Prevalence of restrictive lung function in children and adults in the general population

Risk Factors, Morbidity, and Mortality in Association With Preserved Ratio Impaired Spirometry and Restrictive Spirometric Pattern: Clinical Relevance of Preserved Ratio Impaired Spirometry and Restrictive Spirometric Pattern

BACKGROUND

Preserved ratio impaired spirometry (PRISm) and restrictive spirometric pattern (RSP) are often considered interchangeable in identifying restrictive impairment in spirometry.

RESEARCH QUESTION

Do PRISm and RSP have different individual associations with risk factors, morbidity, and mortality?

STUDY DESIGN AND METHODS

In a cross-sectional and longitudinal study, including 26,091 Norwegian general population men (30 to 46 years of age), we explored the association of PRISm and RSP with smoking habits, BMI, education, respiratory symptoms, self-reported cardiopulmonary disease, and mortality after 26 years of follow-up. PRISm was defined as FEV1/FVC ≥ lower limit of normal (LLN) and FEV1 < LLN, and RSP was defined as FEV1/FVC ≥ LLN and FVC < LLN. We compared the associations of PRISm and RSP to airflow obstruction and normal spirometry, both as mutually (PRISm alone, RSP alone) and nonmutually exclusive (PRISm, RSP) categories, adjusting for age, BMI, smoking, and education. We also conducted sensitivity analyses using Global Initiative for Chronic Obstructive Lung Disease criteria to define spirometric abnormalities.

RESULTS

The prevalence of the mutually exclusive spirometric patterns was as follows: normal 82.4%, obstruction 11.0%, PRISm alone 1.4%, RSP alone 1.7%, and PRISm + RSP 3.5%. PRISm alone patients frequently had obesity (11.2%) and had active or previous tobacco use, commonly reporting cough, phlegm, wheeze, asthma, and bronchitis. RSP alone patients had both obesity (14.6%) and underweight (2.9%), with increased breathlessness, but similar smoking habits to patients with normal spirometry. The prevalence of heart disease was 4.6% in PRISm alone, 2.7% in RSP alone, and 1.6% in obstruction. With normal spirometry as a reference, RSP alone had increased all-cause (hazard ratio [HR], 1.57; 95% CI, 1.21-2.04), cardiovascular (HR, 1.48; 95% CI, 0.88-2.48), diabetes (HR, 6.43; 95% CI, 1.88-21.97), and cancer (excluding lung) mortality (HR, 1.51; 95% CI, 0.95-2.42). PRISm alone had increased respiratory disease mortality (HR, 4.00; 95% CI, 1.22-13.16). Patients with PRISm + RSP had intermediate characteristics and the worst prognosis. Findings were overall confirmed with nonmutually exclusive categories and Global Initiative for Chronic Obstructive Lung Disease criteria.

INTERPRETATION

Our findings indicate that PRISm and RSP are spirometric patterns with distinct risk factors, morbidity, and mortality, which should be differentiated in future studies.

Association between sleep duration and lung function among U.S. adults

BACKGROUND

Sleep's impact on the human immune system and inflammatory responses makes it a potential risk factor for lung function impairment. However, the relationship between sleep duration and lung function impairment in middle-aged and young adults has been rarely investigated.

METHODS

A total of 9,284 aged 20-64 years were categorized into four groups according to sleep duration (≤ 6 h, 7 h, 8 h, and ≥ 9 h), with 7 h as the reference, by using the U.S. NHANES data, 2007-2012. Forced expiratory volume in the 1 s (FEV1), forced vital capacity (FVC), FEV1 to FVC (FEV1/FVC) ratio, peak expiratory flow (PEF), and forced expiratory flow at 25-75% (FEF25 - 75%) were measured by spirometry. Restrictive impairment was defined as baseline FVC < 80% predicted and obstructive impairment as FEV1/FVC < 0.70. Generalized linear regression and logistic regression were performed to estimate the associations between sleep duration and lung function.

RESULTS

Compared with 7 h of sleep duration, shorter and longer sleep duration were associated with decreases in FEV1 (≤ 6 h: β=-0.010, 95% CI=-0.014 to -0.006; 8 h: β=-0.005, 95% CI=-0.009 to -0.001), FVC (≤ 6 h: β=-0.018, 95% CI=-0.014 to -0.007; 8 h: β=-0.005, 95% CI=-0.009 to -0.002), and PEF (≤ 6 h: β=-0.006, 95% CI=-0.010 to -0.002; 8 h: β=-0.007, 95% CI=-0.011 to -0.002; ≥ 9 h: β=-0.012, 95% CI=-0.020 to -0.004). Similarly, shorter (≤ 6 h: OR = 1.346, 95% CI = 1.065 to 1.700) and longer (≥ 9 h: OR = 1.827, 95% CI = 1.236 to 2.700) sleep duration were associated with increased risks of restrictive impairment. Moreover, the aforementioned associations were more pronounced among male participants.

CONCLUSIONS

Compared with 7 h of sleep duration, shorter and longer sleep duration were associated with impaired lung function among adults aged 20-64 years, and these associations were stronger among males.

Restrictive Spirometric Pattern and Preserved Ratio Impaired Spirometry in a Population Aged 50-64 Years

Rationale: Knowledge regarding the prevalence and shared and unique characteristics of the restrictive spirometric pattern (RSP) and preserved ratio impaired spirometry (PRISm) is lacking for a general population investigated with post-bronchodilator spirometry and computed tomography of the lungs. Objectives: To investigate shared and unique features for RSP and PRISm. Methods: In the Swedish CArdioPulmonary bioImage Study (SCAPIS), a general population sample of 28,555 people aged 50-64 years (including 14,558 never-smokers) was assessed. The participants answered a questionnaire and underwent computed tomography of the lungs, post-bronchodilator spirometry, and coronary artery calcification score. Odds ratios with 95% confidence intervals (CIs) were calculated using adjusted logistic regression. RSP was defined as forced expiratory volume in 1 second (FEV1)/forced vital capacity (FVC) ≥0.70 and FVC <80%. PRISm was defined as FEV1/FVC ≥0.70 and FEV1 <80%. A local reference equation was applied. Results: The prevalence of RSP and PRISm were 5.1% (95% CI, 4.9-5.4) and 5.1% (95% CI, 4.8-5.3), respectively, with similar values seen in never-smokers. For RSP and PRISm, shared features were current smoking, dyspnea, chronic bronchitis, rheumatic disease, diabetes, ischemic heart disease, bronchial wall thickening, interstitial lung abnormalities, and bronchiectasis. Emphysema was uniquely linked to PRISm (odds ratio, 1.69; 95% CI, 1.36-2.10) versus 1.10 (95% CI, 0.84-1.43) for RSP. Coronary artery calcification score ≥300 was related to PRISm, but not among never-smokers. Conclusions: PRISm and RSP have respiratory, cardiovascular, and metabolic conditions as shared features. Emphysema is only associated with PRISm. Coronary atherosclerosis may be associated with PRISm. Our results indicate that RSP and PRISm may share more features than not.

Associations between different body mass index and lung function impairment in Chinese people aged over 40 years: a multicenter cross-sectional study

OBJECTIVE

The aim of this study was to explore the associations between different body mass index (BMI) levels and different lung function impairment (LFI) in Chinese people aged over 40 years.

METHODS

We used a multi-stage stratified cluster random sampling method to investigate 3000 residents aged over 40 years from 5 areas in Hubei province of China in 2019-20. The data on questionnaire, physical measurements, and spirometry of the participants were collected. The associations of different BMI levels with different LFI were analyzed using multivariate logistic regressions after complex weighting. The spirometry data were analyzed using one-factor analysis of variance (ANOVA), and post-hoc was performed using the least significance difference (LSD)-t test.

RESULTS

A total of 2860 subjects were included. The prevalence (95%CI) of obstructive lung disease (OLD), restrictive lung disease (RLD), mixed lung disease (MLD), chronic obstructive pulmonary disease (COPD), COPD mild, and COPD moderate/severe/very severe were 24.1% (95% CI: 22.2-26.2), 11.6% (95% CI: 10.3-12.9), 4.0% (95% CI: 3.3-4.8), 12.6% (95% CI: 11.0-14.1), 7.2% (95% CI: 6.0-8.4), and 5.3% (95% CI: 4.3-6.4) respectively. After multivariate adjustment, the risk of OLD, COPD, and COPD mild decreased with the increment of BMI levels (both P for trend < 0.05). When compared to the normal weight group, the overweight group and obese group were at lower risk of experiencing OLD than normal group, the ORs were 0.77 (95% CI: 0.59-0.99) and 0.59 (95% CI: 0.40-0.86) respectively. The obese group was at lower risk for people with COPD mild (OR: 0.42, 95%CI: 0.21-0.85). Participants in underweight group were more likely to experience COPD and COPD moderate/severe/very severe, the ORs were 2.82 (95% CI: 1.07-7.39) and 3.89 (95% CI: 1.28-11.87) respectively.

CONCLUSION

Higher BMI levels were associated with an decreased risk of OLD and COPD. Obesity had a protective effect on lung function in OLD patients and COPD patients. However, there was no significant difference in RLD and MLD prevalence between different BMI groups.