Body mass index and chronic airflow limitation in a worldwide population-based study

Estimating the global prevalence of chronic obstructive pulmonary disease (COPD): a systematic review and meta-analysis

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is a major public health problem. The present study aims to provide a global and regional estimate of the prevalence of COPD based on spirometry according to the two most widely used diagnostic criteria of COPD: fixed ratio (FR) and lower limit of normal (LLN).

METHODS

We conducted a systematic review of the literature according to PRISMA guidelines. MEDLINE, Web of Sciences, and Scopus databases were searched to identify studies on the spirometry-based prevalence of COPD in individuals aged 40 years and older. The meta-analysis was performed using MedCalc 19 software.

RESULTS

In total, 42 of the 3393 studies reviewed were eligible for inclusion. The overall prevalence of COPD in people aged 40 years and older was 12.64% (95% CI 10.75%-14.65%) and 7.38% (95% CI 5.47% - 9.55%) based on FR and LLN criteria, respectively. By gender, men had a higher prevalence of COPD compared to women (15.47%; 95% CI 12.22%-19.02% for men versus 8.79%; 95% CI 6.94%-10.82% for women). Using the LLN criteria, the prevalence of COPD in both sexes was almost identical (8.67%; 95% CI 8.44%- 8.90% for men and 8.00%; 95% CI 6.42% - 9.73% for women). We reported a high prevalence of COPD among smokers and the elderly by both definitions of airway obstruction. Regional prevalence estimates using the FR definition indicate that the highest COPD prevalence was recorded in the Americas and the lowest was recorded in the Eastern Mediterranean region. Using the LLN definition, the highest prevalence was recorded in the Southeast Asian region and the lowest prevalence was recorded in the American region. The most common COPD stage was stage II, with a prevalence of 50.46%. The results indicate a huge lack of prevalence data in the African and Eastern Mediterranean region. The results were given using a random-effect model due to the high heterogeneity between studies.

CONCLUSION

Results show that the prevalence of COPD differs according to the diagnostic criteria used. In addition, management and prevention strategies targeting risk factors for COPD are certainly needed to reduce the global burden of this chronic respiratory disease.

Respiratory health and its determinants among Nunavimmiut: results from the Qanuilirpitaa? 2017 Nunavik Health Survey

OBJECTIVES

Respiratory diseases are the leading cause of hospitalization in Nunavik (northern Québec, Canada) and contribute to disparities in life expectancy with the rest of Canada. As part of Qanuilirpitaa? 2017, a cross-sectional population-based health survey, we sought to describe the prevalence of respiratory health indicators, including the first estimate of airway obstruction based on spirometry in an Inuit population, and explore their associated characteristics.

METHODS

We analyzed data from 1296 participants aged 16 years and older, using multivariate logistic regression to assess characteristics associated with spirometry-determined airway obstruction and self-reported respiratory symptoms, i.e., wheezing in the last year and chronic cough during at least 3 months.

RESULTS

In this relatively young population (83% aged 16 to 54), the prevalences of wheezing, chronic cough, and airway obstruction were, respectively, 27% (95% CI 24-30), 21% (18-23), and 17% (14-20). These estimates are prone to biases due to the relatively low participation rate (about 37%). The most consistent associations were with smoking (≥ 15 pack-years; odds ratio [OR] 3.13, 3.39, and 2.86 for the three indicators, respectively) and food security (OR 0.55 with wheezing and OR 0.26 with chronic cough), as defined in the Household Food Security Survey Module. Wheezing was also associated with allergic sensitization to dogs (2.60) and obesity (2.18). Chronic cough was associated with respiratory infections during childhood (2.12), housing in need of major repairs (1.72), and housing crowding (1.50), and was negatively associated with participation to traditional activities (0.62) and going on the land (0.64). Airway obstruction was associated with being underweight (3.84) and post-secondary education (0.40). Among young adults and women, wheezing was also associated with any inhalation of solvents for recreational purposes during their lifetime (2.62 and 1.56, respectively), while airway obstruction was associated with regular marijuana use (2.22 and 1.84, respectively).

CONCLUSION

Smoking and food insecurity are both highly prevalent and strongly associated with respiratory symptoms in Nunavik. Together with essential smoking prevention and cessation programs, our findings suggest that solving food security and housing crises, improving socioeconomic conditions, and promoting traditional lifestyle may improve respiratory health in Nunavik.

Differential impacts between fat mass index and fat-free mass index on patients with COPD

BACKGROUND

Differences in the clinical impacts of fat mass index (FMI) and fat-free mass index (FFMI) remain unclear in patients with chronic obstructive pulmonary disease (COPD). We hypothesized that FMI and FFMI have different impacts on 1) emphysema and 2) pulmonary function and health-related quality of life of COPD patients.

METHODS

Patients with COPD (n = 228), enrolled in a multicenter prospective 3-year cohort were classified into four groups based on baseline median FMI and FFMI values. Emphysema assessed as the ratio of low attenuation area to total lung volume (LAA%) on computed tomography, pulmonary function, and health-related quality of life assessed using the St. George's Respiratory Questionnaire (SGRQ) were compared.

RESULTS

The four groups had statistically significant differences in LAA%, pulmonary function, and SGRQ scores. The Low FMI Low FFMI group exhibited the highest LAA%, lowest pulmonary function, and worst SGRQ scores among the four groups. In addition, these differences were consistent over 3 years. Multivariate analysis showed that low FMI was associated with high LAA%, low inspiratory capacity/total lung capacity (IC/TLC), and carbon monoxide transfer coefficient (KCO). In contrast, low FFMI was associated with these factors as well as worse SGRQ scores.

CONCLUSION

FMI and FFMI have different effects on the clinical manifestations of COPD. Both low fat and muscle mass contributed to severe emphysema, whereas only low muscle mass contributed to worse health-related quality of life in patients with COPD.

Association between obesity and chronic obstructive pulmonary disease in Moroccan adults: Evidence from the BOLD study

Objective:

The Moroccan cross-sectional study aimed to investigate obesity in association to chronic obstructive pulmonary disease in Fez city.

Methods:

A cross-sectional survey was carried out in Moroccan adults. Anthropometric and spirometry measurements were performed using standardized guidelines.

Results:

Among the 744 participants, 53.9% of were women, with a mean age of 55.27 years (SD = 10.29). Nearly all women declared themselves to be never smokers, while 21% of men were current smokers. Overall, chronic obstructive pulmonary disease prevalence decreased with body mass index (p = 0.01) and waist circumference (p < 0.001). The same trends were also observed in women. The adjusted regression analysis showed a significant independent association between chronic obstructive pulmonary disease and decreasing overweight (OR_a: 0.66; CI_95% (0.40–0.98)), obesity (OR_a: 0.66 CI_95%: (0.36–0.89)), and a decreasing waist circumference-abdominal obesity (OR_a: 0.58 CI_95%: (0.34–0.99)) in the whole population. The same association remains significant in women for overweight (OR_a: 0.18 CI_95%: (0.06–0.54)) and for waist circumference-abdominal obesity (OR_a: 0.40 CI_95%: (0.19–0.85)). All these associations disappeared for men.

Conclusion:

Chronic obstructive pulmonary disease decreases with the increase in body mass index and waist circumference. The effect of waist circumference on the chronic obstructive pulmonary disease was greater among women, regardless of the tobacco factor. A multicenter study would help to confirm the accuracy of these findings in a larger sample of the Moroccan population. Developed lifestyle programs in patients with chronic obstructive pulmonary disease should be considered.

Causal Effects of Body Mass Index on Airflow Obstruction and Forced Mid-Expiratory Flow: A Mendelian Randomization Study Taking Interactions and Age-Specific Instruments Into Consideration Toward a Life Course Perspective

Obesity has complex links to respiratory health. Mendelian randomization (MR) enables assessment of causality of body mass index (BMI) effects on airflow obstruction and mid-expiratory flow. In the adult SAPALDIA cohort, recruiting 9,651 population-representative samples aged 18–60 years at baseline (female 51%), BMI and the ratio of forced expiratory volume in 1 second (FEV₁) to forced vital capacity (FVC) as well as forced mid-expiratory flow (FEF25–75%) were measured three times over 20 follow-up years. The causal effects of BMI in childhood and adulthood on FEV1/FVC and FEF25–75% were assessed in predictive (BMI averaged over 1st and 2nd, lung function (LF) averaged over 2nd and 3rd follow-up; N = 2,850) and long-term cross-sectional models (BMI and LF averaged over all follow-ups; N = 2,728) by Mendelian Randomization analyses with the use of weighted BMI allele score as an instrument variable and two-stage least squares (2SLS) method. Three different BMI allele scores were applied to specifically capture the part of BMI in adulthood that likely reflects tracking of genetically determined BMI in childhood. The main causal effects were derived from models containing BMI (instrumented by BMI genetic score), age, sex, height, and packyears smoked as covariates. BMI interactions were instrumented by the product of the instrument (BMI genetic score) and the relevant concomitant variable. Causal effects of BMI on FEV1/FVC and FEF25–75% were observed in both the predictive and long-term cross-sectional models. The causal BMI- LF effects were negative and attenuated with increasing age, and stronger if instrumented by gene scores associated with childhood BMI. This non-standard MR approach interrogating causal effects of multiplicative interaction suggests that the genetically rooted part of BMI patterns in childhood may be of particular relevance for the level of small airway function and airflow obstruction later in life. The methodological relevance of the results is first to point to the importance of a life course perspective in studies on the etiological role of BMI in respiratory health, and second to point out novel methodological aspects to be considered in future MR studies on the causal effects of obesity related phenotypes.

Frequency and functional translation of low muscle mass in overweight and obese patients with COPD

Background

Cut offs for fat-free mass index (FFMI) and appendicular skeletal muscle mass index (ASMI) are available for diagnosing low muscle mass in patients with COPD. This study aimed to investigate: (1) the frequency of low muscle mass (FFMI and ASMI) applying different cut-offs and (2) the functional translation (clinical impact) of low muscle mass, in patients with COPD stratified into BMI categories.

Methods

Patients with COPD were assessed regarding body composition, exercise capacity, quadriceps muscle strength, symptoms of anxiety and depression, dyspnea and quality of life upon referral to pulmonary rehabilitation. The proportion of patients with low muscle mass was compared among BMI categories. Clinical outcomes between patients with normal and low muscle mass within each BMI category were compared.

Results

469 patients with COPD were included for analyses. The frequency of patients classified as low FFMI varied significantly according to the choice of cut-off (32 to 54%; P < 0.05), whereas the frequency of patients with low ASMI was 62%. When applying age-gender-BMI-specific cut-offs, 254 patients (54%) were classified as low FFMI. The choice of the cut-off affected the frequency of patients with low muscle mass in all BMI categories. Overweight and obese patients with low muscle mass were more frequently males and presented worse pulmonary function, exercise capacity and muscle strength compared with overweight and obese patients with normal muscle mass.

Conclusions

Approximately half of the overweight and obese patients with COPD have low muscle mass when applying age-gender-BMI-specific cut-offs. Low muscle mass is associated with worse functional outcomes in overweight and obese COPD patients.

Prevalence and Population Attributable Risk for Chronic Airflow Obstruction in a Large Multinational Study

Rationale: The Global Burden of Disease programme identified smoking, and ambient and household air pollution as the main drivers of death and disability from Chronic Obstructive Pulmonary Disease (COPD). Objective: To estimate the attributable risk of chronic airflow obstruction (CAO), a quantifiable characteristic of COPD, due to several risk factors. Methods: The Burden of Obstructive Lung Disease study is a cross-sectional study of adults, aged≥40, in a globally distributed sample of 41 urban and rural sites. Based on data from 28,459 participants, we estimated the prevalence of CAO, defined as a post-bronchodilator one-second forced expiratory volume to forced vital capacity ratio < lower limit of normal, and the relative risks associated with different risk factors. Local RR were estimated using a Bayesian hierarchical model borrowing information from across sites. From these RR and the prevalence of risk factors, we estimated local Population Attributable Risks (PAR). Measurements and Main Results: Mean prevalence of CAO was 11.2% in men and 8.6% in women. Mean PAR for smoking was 5.1% in men and 2.2% in women. The next most influential risk factors were poor education levels, working in a dusty job for ≥10 years, low body mass index (BMI), and a history of tuberculosis. The risk of CAO attributable to the different risk factors varied across sites. Conclusions: While smoking remains the most important risk factor for CAO, in some areas poor education, low BMI and passive smoking are of greater importance. Dusty occupations and tuberculosis are important risk factors at some sites.

Metabolic profiles among COPD and controls in the CanCOLD population-based cohort

A high prevalence of intermediate cardiometabolic risk factors and obesity in chronic obstructive pulmonary disease (COPD) has suggested the existence of pathophysiological links between hypertriglyceridemia, insulin resistance, visceral adiposity, and hypoxia or impaired pulmonary function. However, whether COPD contributes independently to the development of these cardiometabolic risk factors remains unclear. Our objective was to compare ectopic fat and metabolic profiles among representative individuals with COPD and control subjects and to evaluate whether the presence of COPD alters the metabolic risk profile. Study participants were randomly selected from the general population and prospectively classified as non-COPD controls and COPD, according to the Global Initiative for Chronic Obstructive Lung Disease classification. The metabolic phenotype, which consisted of visceral adipose tissue area, metabolic markers including homeostasis model assessment of insulin resistance (HOMA-IR), and blood lipid profile, was obtained in 144 subjects with COPD and 119 non-COPD controls. The metabolic phenotype was similar in COPD and controls. The odds ratios for having pathologic values for HOMA-IR, lipids and visceral adipose tissue area were similar in individuals with COPD and control subjects in multivariate analyses that took into account age, sex, body mass index, tobacco status and current medications. In a population-based cohort, no difference was found in the metabolic phenotype, including visceral adipose tissue accumulation, between COPD and controls. Discrepancies between the present and previous studies as to whether or not COPD is a risk factor for metabolic abnormalities could be related to differences in COPD phenotype or disease severity of the study populations.

Multimorbidity in COPD, does sleep matter?

A good night's sleep is a prerequisite for sustainable mental and physical health. Sleep disorders, including sleep disordered breathing, insomnia and sleep related motor dysfunction (e.g., restless legs syndrome), are common in patients with chronic obstructive pulmonary disease (COPD), especially in more severe disease. COPD is commonly associated with multimorbidity, and sleep disorders as a component of this multimorbidity spectrum have a further negative impact on COPD-related comorbidities. Indeed, concomitant diseases in COPD and in obstructive sleep apnea (OSA) are similar, suggesting that the combination of COPD and OSA, the so called OSA-COPD overlap syndrome (OVS), affects patient outcomes. Potential clinically important interactions of OVS exist in cardiovascular and metabolic disease, arthritis, anxiety, depression, neurocognitive disorder and the fatigue syndrome. Correct diagnosis for recognition and treatment of sleep-related disorders in COPD is recommended. However, surprisingly limited information is available and further research and improved diagnostic tools are needed. In the absence of clear evidence, we agree with the recommendation of the Global Initiative on Chronic Obstructive Lung Disease that sleep disorders should be actively searched for and treated in patients with COPD. We believe that both aspects are important components of the holistic approach required in patients with chronic multimorbid conditions.

Optimization of pulmonary emphysema quantification on CT scans of COPD patients using hybrid iterative and post processing techniques: correlation with pulmonary function tests

Objectives

The aim of this study was to assess the effect of hybrid iterative reconstruction and post processing on emphysema quantification in low-dose CT scans of COPD patients using pulmonary function tests (PFT) as a reference.

Methods

CT scans of 23 COPD patients diagnosed with GOLD I or higher were reconstructed with iDose⁴ level 1 to 7 in IntelliSpace Portal (ISP) 6 and 7. ISP7 was used with and without specific denoising filter for COPD. The extent of emphysema was measured as percentage of lung voxels with attenuation < − 950 Hounsfield units (%LAA-950). The correlation between %LAA-950 and PFT, age, BMI, pack years, and the Clinical COPD Questionnaire (CCQ) and Medical Research Council dyspnea scale (MRC) was determined.

Results

Denoising significantly reduced %LAA-950 as was demonstrated by lower %LAA-950 in ISP7 with denoising filter and a significant reduction in %LAA-950 with higher iDose⁴ levels. All PFT except forced vital capacity (FVC) were significantly inversely correlated with %LAA-950. There was a trend toward a stronger correlation at higher iDose⁴ levels. %LAA-950 was also significantly correlated with BMI, GOLD class, and CCQ scores.

Conclusions

Our study showed that hybrid iterative reconstruction and use of post processing denoising can optimize the use of emphysema quantification in CT scans as a complimentary diagnostic tool to stage COPD in addition to PFT.

Airflow Obstruction and Cardio-metabolic Comorbidities

Chronic obstructive pulmonary disease (COPD) is characterized by airflow obstruction and often co-exists with cardiovascular disease (CVD), hypertension and diabetes. This international study assessed the association between airflow obstruction and these comorbidities. 23,623 participants (47.5% males, 19.0% current smokers, age: 55.1 ± 10.8 years) in 33 centers in the Burden of Obstructive Lung Disease (BOLD) initiative were included. 10.4% of subjects had airflow obstruction. Self-reports of physician-diagnosed CVD (heart disease or stroke), hypertension and diabetes were regressed against airflow obstruction (post-bronchodilator FEV1/FVC < 5th percentile of reference values), adjusting for age, sex, smoking (including pack-years), body mass index and education. Analyses were undertaken within center and meta-analyzed across centers checking heterogeneity using the I2-statistic. Crude odds ratios for the association with airflow obstruction were 1.42 (95% CI: 1.20-1.69) for CVD, 1.24 (1.02-1.51) for hypertension, and 0.93 (0.76-1.15) for diabetes. After adjustment these were 1.00 (0.86-1.16) (I2:6%) for CVD, 1.14 (0.99-1.31) (I2:53%) for hypertension, and 0.76 (0.64-0.89) (I2:1%) for diabetes with similar results for men and women, smokers and nonsmokers, in richer and poorer centers. Alternatively defining airflow obstruction by FEV1/FVC < 2.5th percentile or 0.70, did not yield significant other results. In conclusion, the associations of CVD and hypertension with airflow obstruction in the general population are largely explained by age and smoking habits. The adjusted risk for diabetes is lower in subjects with airflow obstruction. These findings emphasize the role of common risk factors in explaining the coexistence of cardio-metabolic comorbidities and COPD.

Obesity and Metabolic Abnormalities in Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) and obesity are major causes of morbidity and mortality worldwide, and a relationship between COPD and obesity is increasingly recognized. The nature and underlying mechanisms of the link between obesity and COPD are still largely unknown. Obesity, and abdominal adiposity in particular, is linked to metabolic syndrome. Hypertension, hyperglycemia, and abdominal adiposity seem to be the most prevalent components of metabolic syndrome in COPD. Adipose tissues function as a source of a variety of signaling molecules in the pathobiology of respiratory diseases. Computed tomography allows measurement of various fat depots and allows better understanding of the impact of abdominal visceral fat in the pathophysiology of COPD. Innovative statistical methodology has identified obesity as a relevant and distinguishing characteristic in patients with COPD. Integrated research combining COPD and its multimorbidity network may unravel underlying endotypes to direct future interventions in this specific COPD cluster.

Obesity and metabolic syndrome in COPD: Is exercise the answer?

Approximately half of all patients with chronic obstructive pulmonary disease (COPD) attending pulmonary rehabilitation (PR) programmes are overweight or obese which negatively impacts upon dyspnoea and exercise tolerance particularly when walking. Within the obese population (without COPD), the observed heterogeneity in prognosis is in part explained by the variability in the risk of developing cardiovascular disease or diabetes (cardiometabolic risk) leading to the description of metabolic syndrome. In obesity alone, high-intensity aerobic training can support healthy weight loss and improve the constituent components of metabolic syndrome. Those with COPD, obesity and/or metabolic syndrome undergoing PR appear to do as well in traditional outcomes as their normal-weight metabolically healthy peers in terms of improvement of symptoms, health-related quality of life and exercise performance, and should therefore not be excluded. To broaden the benefit of PR, for this complex population, we should learn from the extensive literature examining the effects of exercise in obesity and metabolic syndrome discussed in this review and optimize the exercise strategy to improve these co-morbid conditions. Standard PR outcomes could be expanded to include cardiometabolic risk reduction to lower future morbidity and mortality; to this end exercise may well be the answer.

A comprehensive analysis of association of medical history with airflow limitation: a cross-sectional study

Background

Multiple comorbidity is common and increases the complexity of the presentation of patients with COPD. This study was a comprehensive analysis of the relationship between a medical history of 22 disease categories and the presence of airflow limitation (AL) without any history of asthma or bronchiectasis, compatible with COPD.

Methods

A total of 11,898 Japanese patients aged ≥40 years, who underwent spirometry tests, comprising patients with AL (n=2,309) or without AL (n=9,589), were evaluated. Generalized estimating equations were used to assess the relationship between the presence of AL and each disease. The model was adjusted for age, sex, body mass index (BMI) and pack-years of smoking.

Results

In multivariate analysis, female sex (odds ratio [OR]: 0.59; 95% confidence interval [CI]: 0.52–0.67), age (OR for 10-year age increase: 1.99; CI: 1.90–2.09), BMI (OR for 1 kg/m² increase: 0.96; CI: 0.95–0.98) and smoking history (<15 vs 15–24, 25–49 and ≥50 pack-years; OR: 1.78, 2.6 and 3.69, respectively; CI: 1.46–2.17, 2.24–3.0 and 3.15–4.33, respectively) were significantly associated with the presence of AL. In addition, a history of tuberculosis (OR: 1.72; CI: 1.39–2.11), primary lung cancer (OR: 1.50; CI: 1.28–1.77), myocardial infarction (OR: 1.22; CI: 1.01–1.48), heart failure (OR: 1.53; CI: 1.29–1.81), arrhythmia (OR: 1.19; CI: 1.03–1.38) or heart valve disorder (OR: 1.33; CI: 1.14–1.56) was significantly associated with the presence of AL, after adjustment.

Conclusion

This study suggests that a history of heart disease leading to abnormal cardiac function may be associated with AL and that the presence of certain types of heart disease provides a rationale to assess lung status and look for respiratory impairment, including COPD.