Comparison of pre- and post-bronchodilator lung function as predictors of mortality: The HUNT Study

Coffee consumption was associated with a lower prevalence of airflow limitation in postmenopausal women

BACKGROUND

Several studies have suggested a potential correlation between menopause and airflow limitation. However, the presence of protective factors in postmenopausal women remains uncertain. Therefore, our study seeks to examine potential protective factors associated with a reduced prevalence of airflow limitation among postmenopausal women.

METHODS

Postmenopausal women were recruited from the Taiwan Biobank for this cross-sectional study. Airflow limitation was defined by a forced expiratory volume in the first second (FEV1)/forced vital capacity (FVC) ratio <0.7. The participants were categorized into two groups: non-coffee drinkers and coffee drinkers, and the association between coffee consumption and airflow limitation was examined using binary logistic regression models.

RESULTS

A total of 8149 women with available information were enrolled. Compared to the non-coffee drinkers, the coffee drinkers had a significantly lower prevalence of airflow limitation (7% vs. 5%). The odds ratio (OR) for airflow limitation was lower in the coffee drinkers than in the non-coffee drinkers (OR = 0.77; 95% confidence interval [CI] = 0.63 to 0.94) after adjusting for confounding factors. We also examined the association between daily coffee consumption in cups and airflow limitation. The women who consumed ≥2 cups of coffee per day had an OR of 0.74 (95% CI = 0.59 to 0.94) compared to those who did not consume coffee.

CONCLUSIONS

Our results suggest that habitual coffee consumption is associated with a reduction in the prevalence of airflow limitation in postmenopausal women, warranting further prospective studies to explore possible causal effects and mechanisms.

Establishing an optimal diagnostic criterion for respiratory sarcopenia using peak expiratory flow rate

BACKGROUND

The skeletal muscle changes as aging progresses, causing sarcopenia in the older adult population, which affects the respiratory muscles' mass, strength, and function. The optimal cut-off point of peak expiratory flow rate (PEFR) for respiratory sarcopenia (RS) diagnosis in accordance with sarcopenia identification is needed.

AIM

To establish an optimal cut-off point of PEFR for RS diagnosis in community-dwelling Asian older women.

METHODS

Sarcopenia diagnostic indicators were evaluated according to the Asian Working Group for Sarcopenia 2019 (AWGS) criteria. The respiratory parameters composed of respiratory muscle strength and respiratory function were evaluated by assessing maximal inspiratory pressure (MIP), percent predicted forced vital capacity (Pred FVC), and PEFR.

RESULTS

A total of 325 community-dwelling older women were included in this study. PEFR was negatively associated with RS (OR: 0.440; 95% CI: 0.344-0.564). The area under the curve (AUC) of PEFR was 0.772 (p < 0.001). The optimal cut-off point of PEFR for RS diagnosis was 3.4 l/s (sensitivity, 63.8%; specificity, 77.3%). Significant differences were found between the robust, possible sarcopenia, sarcopenia, and RS groups in terms of both sarcopenia diagnostic indicators and respiratory parameters (p < 0.05).

CONCLUSIONS

The cut-off point of PEFR can be used as a reasonable standard for RS diagnosis. This study finding can serve as a cornerstone for developing concrete criteria of RS in older women, supporting clinical judgment, which is crucial for providing appropriate treatment through accurate diagnosis.

Preserved Ratio Impaired Spirometry and COPD Accelerate Frailty Progression: Evidence From a Prospective Cohort Study

BACKGROUND

COPD has been found to be associated with frailty. However, longitudinal evidence for associations of COPD with frailty progression is inadequate. Furthermore, recent studies revealed a new phenotype of lung function impairment: preserved ratio impaired spirometry (PRISm) findings. Associations of PRISm findings and their transitions with frailty progression are unclear.

RESEARCH QUESTION

What are the associations of PRISm findings, transitions of PRISm findings, and COPD with frailty progression?

STUDY DESIGN AND METHODS

To analyze the associations of PRISm findings and COPD with frailty progression, 5,901 patients were included from the English Longitudinal Study of Ageing. Patients were classified into three lung function patterns of normal spirometry (NS) findings, PRISm findings, and COPD. Frailty progression was assessed by repeated measurements of the frailty index (FI) during follow-up. Among these 5,901 patients, 3,765 patients were included to analyze the associations of PRISm findings transitions with frailty progression. PRISm findings transitions were assessed based on the changes of lung function patterns after a 4-year interval. Linear mixed-effect models were used for statistical analyses.

RESULTS

The median follow-up periods were 9.5 years for the analyses of PRISm findings and COPD with frailty progression and 5.8 years for PRISm findings transitions with frailty progression. When compared with participants with NS findings, patients with PRISm findings and COPD demonstrated accelerated FI progression with additional annual increases of 0.301 (95% CI, 0.211-0.392; P < .001) and 0.172 (95% CI, 0.102-0.242; P < .001), respectively. Patients who transitioned from NS findings to PRISm findings also demonstrated accelerated FI progression when compared with those with stable NS findings (β = 0.242; 95% CI, 0.008-0.476; P = .042). However, no accelerated FI progression was found in patients with PRISm findings who transitioned to NS findings (β = 0.119; 95% CI, -0.181 to 0.418; P = .438).

INTERPRETATION

Our findings indicate that PRISm findings and COPD are associated with accelerated frailty progression. Further studies are needed to elucidate the causality of the association of PRISm findings and COPD with frailty.

Association of non-obstructive dyspnoea with all-cause mortality and incident chronic obstructive pulmonary disease: a systematic literature review and meta-analysis

BACKGROUND

Controversy exists regarding the association between non-obstructive dyspnoea and the future development of chronic obstructive pulmonary disease (COPD) and mortality. Therefore, we aimed to evaluate the association of non-obstructive dyspnoea with mortality and incident COPD in adults.

METHODS

We searched PubMed, Embase, and Web of Science to identify studies published from inception to 13 May 2023. Eligibility screening, data extraction, and quality assessment of the retrieved articles were conducted independently by two reviewers. Studies were included if they were original articles comparing incident COPD and all-cause mortality between individuals with normal lung function with and without dyspnoea. The primary outcomes were incident COPD and all-cause mortality. The secondary outcome was respiratory disease-related mortality. We used the random-effects model to calculate pooled estimates and corresponding 95% confidence interval (CI). Heterogeneity was determined using the I² statistic.

RESULTS

Of 6486 studies, 8 studies involving 100 758 individuals fulfilled the inclusion and exclusion criteria and were included in the study. Compared with individuals without non-obstructive dyspnoea, individuals with non-obstructive dyspnoea had an increased risk of incident COPD (relative risk: 1.41, 95% CI: 1.08 to 1.83), and moderate heterogeneity was found (p=0.079, I2=52.2%). Individuals with non-obstructive dyspnoea had a higher risk of all-cause mortality (hazard ratio: 1.21, 95% CI: 1.14 to 1.28, I2=0.0%) and respiratory disease-related mortality (hazard ratio: 1.52, 95% CI: 1.14 to 2.02, I2=0.0%) than those without.

CONCLUSIONS

Individuals with non-obstructive dyspnoea are at a higher risk of incident COPD and all-cause mortality than individuals without dyspnoea. Further research should investigate whether these high-risk adults may benefit from risk management and early therapeutic intervention.

PROSPERO REGISTRATION NUMBER

CRD42023395192.

MAIT cell counts are associated with the risk of hospitalization in COPD

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is characterized by persistent airflow limitation associated with chronic inflammation in the airways. Mucosal-associated invariant T (MAIT) cells are unconventional, innate-like T cells highly abundant in mucosal tissues including the lung. We hypothesized that the characteristics of MAIT cells in circulation may be prospectively associated with COPD morbidity.

METHODS

COPD subjects (n = 61) from the Tools for Identifying Exacerbations (TIE) study were recruited when in stable condition. At study entry, forced expiratory volume in 1 s (FEV₁) was measured and peripheral blood mononuclear cells were cryopreserved for later analysis by flow cytometry. Patients were followed for 3 years to record clinically meaningful outcomes.

RESULTS

Patients who required hospitalization at one or more occasions during the 3-year follow-up (n = 21) had lower MAIT cell counts in peripheral blood at study inclusion, compared with patients who did not get hospitalized (p = 0.036). In contrast, hospitalized and never hospitalized patients did not differ in CD8 or CD4 T cell counts (p = 0.482 and p = 0.221, respectively). Moreover, MAIT cells in hospitalized subjects showed a more activated phenotype with higher CD38 expression (p = 0.014), and there was a trend towards higher LAG-3 expression (p = 0.052). Conventional CD4 and CD8 T cells were similar between the groups. Next we performed multi-variable logistic regression analysis with hospitalizations as dependent variable, and FEV₁, GOLD 2017 group, and quantity or activation of MAIT and conventional T cells as independent variables. MAIT cell count, CD38 expression on MAIT cells, and LAG-3 expression on both MAIT and CD8 T cells were all independently associated with the risk of hospitalization.

CONCLUSIONS

These findings suggest that MAIT cells might reflect a novel, FEV₁-independent immunological dimension in the complexity of COPD. The potential implication of MAIT cells in COPD pathogenesis and MAIT cells' prognostic potential deserve further investigation.

Preserved ratio impaired spirometry is associated with small airway dysfunction and reduced total lung capacity

BACKGROUND

Preserved ratio impaired spirometry (PRISm) refers to decreased forced expiratory volume in 1 s (FEV₁) in the setting of preserved ratio. Little is known about the role of PRISm and its complex relation with small airway dysfunction (SAD) and lung volume. Therefore, we aimed to investigate the associations between PRISm and SAD and lung volume.

METHODS

We conducted a cross-sectional community-dwelling study in China. Demographic data, standard respiratory epidemiology questionnaire, spirometry, impulse oscillometry (IOS) and computed tomography (CT) data were collected. PRISm was defined as post-bronchodilator FEV₁/FVC ≥ 0.70 and FEV₁ < 80% predicted. Spirometry-defined SAD was defined as at least two of three of the post-bronchodilator maximal mid-expiratory flow (MMEF), forced expiratory flow 50% (FEF50), and forced expiratory flow 75% (FEF75) less than 65% of predicted. IOS-defined SAD and CT-defined gas trapping were defined by the fact that the cutoff value of peripheral airway resistance R5-R20 > 0.07 kPa/L/s and LAA_- 856>20%, respectively. Analysis of covariance and logistic regression were used to determine associations between PRISm and SAD and lung volume. We then repeated the analysis with a lower limit of normal definition of spirometry criteria and FVC definition of PRISm. Moreover, we also performed subgroup analyses in ever smoker, never smoker, subjects without airway reversibility or self-reported diagnosed asthma, and subjects with CT-measured total lung capacity ≥70% of predicted.

RESULTS

The final analysis included 1439 subjects. PRISm had higher odds and more severity in spirometry-defined SAD (pre-bronchodilator: odds ratio [OR]: 5.99, 95% confidence interval [95%CI]: 3.87-9.27, P < 0.001; post-bronchodilator: OR: 14.05, 95%CI: 8.88-22.24, P < 0.001), IOS-defined SAD (OR: 2.89, 95%CI: 1.82-4.58, P < 0.001), and CT-air trapping (OR: 2.01, 95%CI: 1.08-3.72, P = 0.027) compared with healthy control after adjustment for confounding factors. CT-measured total lung capacity in PRISm was lower than that in healthy controls (4.15 ± 0.98 vs. 4.78 ± 1.05 L, P < 0.05), after adjustment. These results were robust in repeating analyses and subgroup analyses.

CONCLUSION

Our finding revealed that PRISm was associated with SAD and reduced total lung capacity. Future studies to identify the underlying mechanisms and longitudinal progression of PRISm are warranted.

Ten-year prediction model for post-bronchodilator airflow obstruction and early detection of COPD: development and validation in two middle-aged population-based cohorts

BACKGROUND

Classifying individuals at high chronic obstructive pulmonary disease (COPD)-risk creates opportunities for early COPD detection and active intervention.

OBJECTIVE

To develop and validate a statistical model to predict 10-year probabilities of COPD defined by post-bronchodilator airflow obstruction (post-BD-AO; forced expiratory volume in 1 s/forced vital capacity<5th percentile).

SETTING

General Caucasian populations from Australia and Europe, 10 and 27 centres, respectively.

PARTICIPANTS

For the development cohort, questionnaire data on respiratory symptoms, smoking, asthma, occupation and participant sex were from the Tasmanian Longitudinal Health Study (TAHS) participants at age 41-45 years (n=5729) who did not have self-reported COPD/emphysema at baseline but had post-BD spirometry and smoking status at age 51-55 years (n=2407). The validation cohort comprised participants from the European Community Respiratory Health Survey (ECRHS) II and III (n=5970), restricted to those of age 40-49 and 50-59 with complete questionnaire and spirometry/smoking data, respectively (n=1407).

STATISTICAL METHOD

Risk-prediction models were developed using randomForest then externally validated.

RESULTS

Area under the receiver operating characteristic curve (AUCROC) of the final model was 80.8% (95% CI 80.0% to 81.6%), sensitivity 80.3% (77.7% to 82.9%), specificity 69.1% (68.7% to 69.5%), positive predictive value (PPV) 11.1% (10.3% to 11.9%) and negative predictive value (NPV) 98.7% (98.5% to 98.9%). The external validation was fair (AUCROC 75.6%), with the PPV increasing to 17.9% and NPV still 97.5% for adults aged 40-49 years with ≥1 respiratory symptom. To illustrate the model output using hypothetical case scenarios, a 43-year-old female unskilled worker who smoked 20 cigarettes/day for 30 years had a 27% predicted probability for post-BD-AO at age 53 if she continued to smoke. The predicted risk was 42% if she had coexistent active asthma, but only 4.5% if she had quit after age 43.

CONCLUSION

This novel and validated risk-prediction model could identify adults aged in their 40s at high 10-year COPD-risk in the general population with potential to facilitate active monitoring/intervention in predicted 'COPD cases' at a much earlier age.

Significance of FEV3/FEV6 in recognition of early airway disease in smokers at risk of development of COPD: Analysis of the SPIROMICS cohort

BACKGROUND

Small airways are known to be affected early in the course of chronic obstructive pulmonary disease (COPD); however, traditional spirometric indices may not accurately identify small airways disease.

RESEARCH QUESTION

Can FEV₃/FEV₆ identify early airflow abnormalities and predict future clinically important respiratory-related outcomes, including development of COPD?

STUDY DESIGN AND METHODS

We included eight hundred thirty-two current and former smokers with post-bronchodilator FEV₁/FVC ≥0.7 from the SPIROMICS cohort. Participants were classified as having a reduced pre-bronchodilator FEV₃/FEV₆ based on lower limit of normal (LLN) values. Repeatability analysis was performed for FEV₃ and FEV₆. Regression modeling was used to evaluate the relationship between baseline FEV₃/FEV₆ and outcome measures including functional small airways disease on thoracic imaging and respiratory exacerbations. Interval censored analysis was used to assess progression to COPD.

RESULTS

FEV₃/FEV₆ <LLN at baseline, defined as reduced compared to FEV₃/FEV₆ ≥LLN, was associated with lower FEV₁, poorer health status (St. George's Respiratory Questionnaire score), more emphysema, and more functional small airways disease on quantitative imaging. FEV₃ and FEV₆ showed excellent agreement between repeat measurements. A reduced FEV₃/FEV₆ was associated with increased odds of a severe respiratory exacerbation within the first year of follow-up and decreased time to first exacerbation. A low FEV₃/FEV₆ was also associated with development of COPD by spirometry (post-bronchodilator FEV₁/FVC <0.7) during study follow-up.

INTERPRETATION

FEV₃/FEV₆ is a routinely available and repeatable spirometric index which can be useful in the evaluation of early airflow obstruction in current and former smokers without COPD. A reduced FEV₃/FEV₆ can identify those at risk for future development of COPD and respiratory exacerbations.

Underdiagnosis of obstructive lung disease: findings from the French CONSTANCES cohort

BACKGROUND

The burden of undiagnosed obstructive lung disease (OLD) (mainly asthma and chronic obstructive pulmonary disease) is not fully established, and targets for corrective action are yet to be identified. We assessed the underdiagnosis of OLD and its determinants in France.

METHODS

CONSTANCES is a French population-based cohort of adults aged 18-69 years at inception. We analysed data collected at inclusion in 2013-2014. Undiagnosed OLD was defined as spirometry-confirmed airflow limitation (FEV1/FVC < lower limit of normal) without prior diagnosis of asthma, chronic obstructive pulmonary disease, or bronchiectasis. Multivariate analysis was performed with weighted robust Poisson regression models to estimate the adjusted prevalence ratios (aPR) of undiagnosed OLD.

RESULTS

Spirometry results were available for 19,398 participants. The prevalence of airflow limitation was 4.6%. Overall, 64.4% of adults with airflow limitation did not report a previous diagnosis of OLD. Individuals with high cumulative tobacco consumption (≥ 10 pack-years) (aPR: 1.72 [1.28-2.32]), without respiratory symptoms (aPR: 1.51 [1.28-1.78]), and with preserved lung function (aPR: 1.21 [1.04-1.41] for a 10-point increase in FEV1% predicted) had a higher risk of being undiagnosed. Half of symptomatic individuals with airflow limitation (45% of those with moderate to severe airflow limitation) were undiagnosed with OLD.

CONCLUSION

Underdiagnosis of OLD is very common among French adults, even in patients with respiratory symptoms. Efforts should be made in France to raise awareness about OLD in the general population, improve the detection of respiratory symptoms, and increase the use of spirometry among primary care professionals.

Utility of Self-Administered Questionnaires for Identifying Individuals at Risk of COPD in Japan: The OCEAN (Okinawa COPD casE finding AssessmeNt) Study

Purpose

A considerable proportion of patients with chronic obstructive pulmonary disease (COPD) remain undiagnosed and untreated even though they may have a burden of respiratory symptoms that impact quality of life. The OCEAN study assessed the ability of screening questionnaires to identify individuals with, or at risk of, COPD by comparing questionnaire outcomes with spirometric measures of lung function.

Methods

This observational study included participants ≥40 years of age presenting for their annual health examination at a single medical center in Okinawa, Japan. Participants completed COPD screening questionnaires (CAPTURE and COPD-Q), the Chronic Airways Assessment Test (CAAT), and general demographic and health-related questionnaires. The performance characteristics of CAPTURE and COPD-Q were compared with spirometry-based airflow limitation by calculating the area under the receiver operating characteristic (ROC-AUC) curve.

Results

A total of 2518 participants were included in the study; 79% of whom were <60 years of age (mean 52.0 years). A total of 52 (2.1%) participants had airflow limitation defined as forced expiratory volume in 1 second (FEV₁)/forced vital capacity (FVC) <0.7, and 420 (16.7%) participants were classified as Preserved Ratio Impaired Spirometry (PRISm). Among participants with PRISm, 75 (17.9%) had a CAAT total score ≥10. Airflow limitation and PRISm were more prevalent in current smokers versus past smokers. For the CAPTURE questionnaire, ROC-AUC for screening airflow limitation, PRISm, and PRISm with a CAAT total score ≥10 were 0.59, 0.55, and 0.69, respectively; for COPD-Q, these three clinical features were 0.67, 0.58 and 0.68, respectively.

Conclusion

This study demonstrated that CAPTURE and COPD-Q appear to be effective screening tools for identifying symptomatic individuals with undiagnosed, or at risk of developing COPD in adults ≥40 years of age in Okinawa. Furthermore, early diagnosis and management of PRISm is important to improve future outcomes and the societal burden of disease.

Estimation of an Exposure Threshold Value for Compensation of Silica-Induced COPD Based on Longitudinal Changes in Pulmonary Function

(1) Background: To estimate the cumulative exposure to respirable crystalline silica (RCS) that reduces lung function to an extent corresponding with airway obstruction equivalent to chronic obstructive pulmonary disease (COPD). (2) Methods: The study is based on a miners' cohort with longitudinal data on lung function and RCS exposure. Random-effects linear regression models, allowing for a possible threshold concerning the exposure concentration were used to analyze the impact of RCS on the ratio of forced expiratory volume in 1 s and forced vital capacity (FEV₁/FVC). The proposed threshold is the amount of RCS resulting in a decrease in FEV₁/FVC from the expected value to the lower limit of normal. (3) Results: The analysis shows that a threshold model fits the data significantly better than the usual linear model. The estimated threshold value for the exposure concentration is 0.089 mg/m³. Using this threshold, the estimate for the corresponding reference dose for RCS is 2.33 mg/m³·y. (4) Conclusions: The analysis confirmed that RCS has a negative impact on lung function. The effect is primarily due to exposure above a concentration threshold of 0.1 mg/m³. It is recommended that COPD should be compensated as an occupational disease if cumulative exposure was at least 2 mg/m³·y above this threshold.