Do obese adults have a higher risk of asthma attack when exposed to indoor mold? A study based on the 2005 Behavioral Risk Factor Surveillance System

What Are the Effects of Electronic Cigarettes on Lung Function Compared to Non-Electronic Cigarettes? A Systematic Analysis

Objective: The effects of e-cigarettes on lung function were compared between the e-cigarette and the non-e-cigarette group, as well as self-changes after inhaling e-cigarettes.

Method: From March 1st, 2022, relevant literature was selected from four databases through a predefined retrieval strategy. Strict literature screening and quality evaluation were conducted. The study followed PRISMA guidelines.

Results: Our results showed that CO (SMD: −1.48, 95%: −2.82–0.15) and FeNO (SMD: −0.66, 95%: −1.32, −0.01) were significantly decreased after e-cigarette usage. Only asthmatic smokers showed a statistically significant increase in flow resistance after inhaling e-cigarettes. Conversely, the decrease of FEV1/FVC% in the non-e-cigarette groups exceeded that in the e-cigarette group (SMD:1.18, 95%: 0.11–2.26). The degree of O₂ saturation decrease was also less than that for the cigarette groups (SMD:0.32, 95%: 0.04–0.59), especially when compared to the conventional cigarette group (SMD:0.56, 95%: 0.04–1.08).

Conclusion: The current findings indicate that short-term e-cigarette inhalation has a similar (but not significant) effect on lung function, as compared with non-e-cigarettes. More clinical studies are needed to explore the safety of inhaling e-cigarettes, especially in vulnerable populations.

Asthma interactions between obesity and other risk factors

OBJECTIVE

To review and critically discuss published evidence on interactions between obesity and selected risk factors on asthma in children and adults, and to discuss potential future directions in this field.

DATA SOURCES

National Library of Medicine (via PubMed) STUDY SELECTION: A literature search was conducted for human studies on obesity and selected interactions (with sex, race and ethnicity, socioeconomic status, indoor and outdoor pollutants, depression, anxiety, and diet) on asthma. Studies that were published in English and contained a full text were considered for inclusion in this review.

RESULTS

Current evidence supports interactions between obesity and outdoor and indoor air pollutants (including second-hand smoke [SHS]) on enhancing asthma risk, although there are sparse data on the specific pollutants underlying such interactions. Limited evidence also suggests that obesity may modify the effects of depression or anxiety on asthma, whereas little is known about potential interactions between obesity and sex-hormone levels or dietary patterns.

CONCLUSION

Well-designed observational prospective studies (eg, for pollutants and sex hormones) and randomized clinical trials (eg, for the treatment of depression) should help establish the impact of modifying coexisting exposures to reduce the harmful effects of obesity on asthma. Such studies should be designed to have a sample size that is large enough to allow adequate testing of interactions between obesity and risk factors that are identified a priori and thus, well characterized, using objective measures and biomarkers (eg, urinary or serum cotinine for SHS, epigenetic marks of specific environmental exposures).

Indoor Microbial Exposures and Chronic Lung Disease: From Microbial Toxins to the Microbiome

Effects of environmental microbial exposures on human health have long been of interest. Microbes were historically assumed to be harmful, but data have suggested that microbial exposures can modulate the immune system. We focus on the effects of indoor environmental microbial exposure on chronic lung diseases. We found contradictory data in bacterial studies using endotoxin as a surrogate for bacterial exposure. Contradictory data also exist in studies of fungal exposure. Many factors may modulate the effect of environmental microbial exposures on lung health, including coexposures. Future studies need to clarify which method of assessing environmental microbial exposures is most relevant.

Exposure and Health Effects of Fungi on Humans

Fungi are ubiquitous microorganisms that are present in outdoor and indoor environments. Previous research has found relationships between environmental fungal exposures and human health effects. We reviewed recent articles focused on fungal exposure and dampness as risk factors for respiratory disease development, symptoms, and hypersensitivity. In particular, we reviewed the evidence suggesting that early exposure to dampness or fungi is associated with the development of asthma and increased asthma morbidity. Although outdoor exposure to high concentrations of spores can cause health effects such as asthma attacks in association with thunderstorms, most people appear to be relatively unaffected unless they are sensitized to specific genera. Indoor exposure and dampness, however, appears to be associated with an increased risk of developing asthma in young children and asthma morbidity in individuals who have asthma. These are important issues because they provide a rationale for interventions that might be considered for homes and buildings in which there is increased fungal exposure. In addition to rhinitis and asthma, fungus exposure is associated with a number of other illnesses including allergic bronchopulmonary mycoses, allergic fungal sinusitis, and hypersensitivity pneumonitis. Additional research is necessary to establish causality and evaluate interventions for fungal- and dampness-related health effects.

Indoor environmental exposures and exacerbation of asthma: an update to the 2000 review by the Institute of Medicine

BACKGROUND

Previous research has found relationships between specific indoor environmental exposures and exacerbation of asthma.

OBJECTIVES

In this review we provide an updated summary of knowledge from the scientific literature on indoor exposures and exacerbation of asthma.

METHODS

Peer-reviewed articles published from 2000 to 2013 on indoor exposures and exacerbation of asthma were identified through PubMed, from reference lists, and from authors' files. Articles that focused on modifiable indoor exposures in relation to frequency or severity of exacerbation of asthma were selected for review. Research findings were reviewed and summarized with consideration of the strength of the evidence.

RESULTS

Sixty-nine eligible articles were included. Major changed conclusions include a causal relationship with exacerbation for indoor dampness or dampness-related agents (in children); associations with exacerbation for dampness or dampness-related agents (in adults), endotoxin, and environmental tobacco smoke (in preschool children); and limited or suggestive evidence for association with exacerbation for indoor culturable Penicillium or total fungi, nitrogen dioxide, rodents (nonoccupational), feather/down pillows (protective relative to synthetic bedding), and (regardless of specific sensitization) dust mite, cockroach, dog, and dampness-related agents.

DISCUSSION

This review, incorporating evidence reported since 2000, increases the strength of evidence linking many indoor factors to the exacerbation of asthma. Conclusions should be considered provisional until all available evidence is examined more thoroughly.

CONCLUSION

Multiple indoor exposures, especially dampness-related agents, merit increased attention to prevent exacerbation of asthma, possibly even in nonsensitized individuals. Additional research to establish causality and evaluate interventions is needed for these and other indoor exposures.

The asthma phenotype in the obese: distinct or otherwise?

Asthma is a heterogenous disorder that can be classified into several different phenotypes. Recent cluster analyses have identified an “obese-asthma” phenotype which is characterized by late onset, female predominance and lack of atopy. In addition, obesity among early-onset asthmatics clearly exists and heightens the clinical presentation. Observational studies have demonstrated that asthma among the obese has a clinical presentation that is more severe, harder to control, and is not as responsive to standard controller therapies. While weight loss studies have demonstrated improvement in asthma outcomes, further studies need to be performed. The current knowledge of the existence of two obesity-asthma phenotypes (early- versus late-onset asthma) should encourage investigators to study these entities separately since just as they have distinct presentations, their course, response to therapies, and weight loss strategies may be different as well.

Effects of obstructive sleep apnea and gastroesophageal reflux disease on asthma control in obesity

BACKGROUND

Obesity is a risk factor for asthma. Obese asthmatics often have poor asthma control and respond poorly to therapy. It has been suggested that co-morbidities associated with obesity, such as reflux and obstructive sleep apnea, could be important factors contributing to poor asthma control in obese patients.

OBJECTIVES

The purpose of this study was to determine if (1) reflux and/or (2) symptoms of sleep apnea contribute to poor asthma control in obesity.

METHODS

We studied asthmatic subjects participating in a trial of reflux treatment. Participants underwent baseline evaluation of asthma symptoms and lung function. Overall 304 participants underwent esophageal pH probe testing; 246 participants were evaluated for obstructive sleep apnea symptoms.

RESULTS

Of 402 participants in this trial, 51% were obese. Role of reflux in asthma control. Those with higher body mass index (BMI) reported a higher prevalence of reflux symptoms, but the prevalence of pH probe acid reflux was similar in all groups. Reflux was not associated with measures of asthma control in obese patients. Role of obstructive sleep apnea in asthma control. Symptoms and self-report of obstructive sleep apnea were more common with increasing BMI and associated with worse asthma control as measured by the Juniper Asthma Control questionnaire and Asthma Symptom Utility Index.

CONCLUSIONS

Our data suggest that obstructive sleep apnea, but not gastroesophageal reflux disease, may contribute significantly to poor asthma control in obese patients.

Does age impact the obese asthma phenotype? Longitudinal asthma control, airway function, and airflow perception among mild persistent asthmatics

BACKGROUND

The relationship between obesity and asthma remains inadequately defined. Studies about how obesity affects asthma control and lung function show conflicting results. Additional focus on the effect of age as a modifier may make clearer the interaction between obesity and asthma phenotype. We sought to use a diverse and well-phenotyped cohort of asthmatic patients to determine how age impacts the relationship between obesity and spirometry, peak flow variability, airflow perception, and asthma control.

METHODS

The characteristics of 490 patients with mild persistent asthma taken from 2,794 study visits from a prospective trial studying strategies of step-down therapy were included in this post hoc analysis. A longitudinal mixed-effect model was used to determine if age affects the relationship between obesity and asthma characteristics, including spirometry, asthma control, airway pH, and perception of airflow changes.

RESULTS

The effect of obesity on asthma outcomes changes with age and gender. Obese 6- to 11-year-old children had the largest reduction in lung function but reported relatively fewer asthma symptoms than did similar nonobese asthmatics. Obese 12- to 17-year-olds showed a trend toward greater airflow obstruction and asthma symptoms compared with nonobese asthmatics. Adults in general displayed few obesity-related alterations in asthma phenotype. Female gender among 12- to 17- and 18- to 44-year-olds was associated with greater obesity-related asthma impairment.

CONCLUSIONS

Age is a significant effect modifier on the relationship between obesity and asthma phenotype. With increasing age, the influence of obesity on the asthma phenotype is generally reduced. The asthma phenotype may be most impacted by obesity among children and women.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT00156819; URL: www.clinicaltrials.gov.

Effect of obesity on asthma phenotype is dependent upon asthma severity

BACKGROUND

We recently reported that obese and non-obese patients with asthma have similar airflow limitation and bronchodilator responsiveness, but obese patients have more symptoms overall. There is limited information on the effect of obesity on asthmatics of varying severity measured by objective physiological parameters. Understanding how obesity affects asthmatics of differing severity can provide insights into the pathogenesis of asthma in the obese and a rationale for the therapeutic approach to such patients.

METHODS

Participants with asthma from two American Lung Association--Asthma Clinical Research Center (ALA-ACRC) studies were grouped by tertiles of airflow obstruction (forced expiratory volume in one second (FEV(1)%) predicted, FEV(1)/forced vital capacity (FVC)) and methacholine reactivity (PC(20)FEV(1)). Within each tertile, we examined the independent effect of body mass index (BMI), divided into normal weight, overweight, and obese categories, on lung function, airway reactivity, and symptoms.

RESULTS

Overall, both FEV(1) and FVC decreased and symptoms worsened with increasing BMI; airway reactivity was unchanged. When stratified by the degree of airflow obstruction, higher BMI was not associated with greater airway reactivity to methacholine. Higher BMI was associated with more asthma symptoms only in the least obstructed FEV(1)/FVC tertile. When stratified by degree of airway reactivity, BMI was inversely associated with FVC in all PC(20)FEV(1) tertiles. BMI was directly associated with asthma symptoms only in those with the least airway reactivity.

CONCLUSIONS

Obesity does not influence airway reactivity in patients with asthma and it is associated with more symptoms only in those with less severe disease.

Does obesity produce a distinct asthma phenotype?

Obesity and asthma prevalence have been increasing over the past decade. Epidemiological evidence demonstrates that obesity results in an increased risk of developing incident asthma. Even modest levels of increased weight increase asthma risk. Recently published data suggest that obese asthma patients may represent a distinct phenotype of asthma. Obese asthma patients demonstrate increased asthma severity, as indicated by increased exacerbations and decreased asthma control; however, they do not appear to have increased airway cellular inflammation. It seems likely that obesity does not contribute to asthma through conventional Th type 2-mediated inflammatory pathways but, rather, through separate mechanisms that are specific to the obese state. This may explain the variable responses of obese asthma patients to conventional asthma therapies, specifically, relative corticosteroid resistance. Small studies suggest improvements in the disease with weight loss in obese asthma patients, and other interventions to target asthma in obese individuals need to be investigated. Several postulated mechanisms for the occurrence of this distinct phenotype have been postulated: 1) the presence of comorbidities, such as gastroesophageal reflux disease and sleep disordered breathing, 2) systemic inflammation associated with obesity (with elevated levels of circulating cytokines, such as IL-6 and TNF-alpha), 3) increased oxidative stress, and 4) hormones of obesity, such as adiponectin, leptin, and resistin. Although the mechanisms underlying obesity in asthma require further investigation, obesity plays a major role in the asthma epidemic and likely results in a distinct phenotype of the disease.