Obesity is not associated with mild asthma diagnosis in a population of Spanish adults

Relationship between upper airway diseases, exhaled nitric oxide, and bronchial hyperresponsiveness to methacholine

OBJECTIVE

The "united airway disease" concept is based on the bidirectional interaction between asthma and rhinitis. The aim of this study was to determine the relationship between upper airway diseases and bronchial hyperresponsiveness (BHR), as well as their association with the fractional concentration of exhaled nitric oxide (FeNO) and atopy in patients with persistent symptoms suggestive of asthma requiring methacholine challenge testing (MCT) to confirm asthma diagnosis.

METHODS

A cross-sectional prospective study was carried out in adult patients with persistent asthma-like symptoms and negative bronchodilator testing. FeNO and MCT were performed in all patients. Asthma was confirmed based on the presence of suggestive symptoms and MCT results. Associated upper airway diseases included allergic rhinitis, nonallergic rhinitis, chronic rhinosinusitis with nasal polyps (CRSwNP), and aspirin-exacerbated respiratory disease (AERD).

RESULTS

The study included 575 patients; asthma was confirmed in 32.3%, and FeNO values ≥ 50 ppb were found in 27% of the patients. Elevated FeNO was significantly associated to AERD. The prevalence of atopy in asthma patients was 86.6%. Atopy was present in 90.4% of patients with asthma and FeNO levels ≥ 50 ppb. A significant association was found between AERD, asthma, and FeNO ≥ 50 ppb.

CONCLUSIONS

Patients with symptoms suggestive of asthma but negative bronchodilator testing are commonly seen in usual practice. In this population, the association of high FeNO levels and BHR to atopy, as well as to AERD, suggests the presence eosinophilic inflammation in both the upper and lower airways and supports the "one airway" hypothesis.

Impact of anxiety and depression on respiratory symptoms

Psychological factors such as anxiety and depression are prevalent in patients with asthma. The purpose of this study was to investigate the relationship between respiratory symptoms and psychological status and to estimate the importance of psychological status in comparison with other factors that are known to be associated with respiratory symptoms. This study included 2270 subjects aged 20-44 (52% female) from Sweden, Iceland, and Norway. Each participant underwent a clinical interview including questions on respiratory symptoms. Spirometry and methacholine challenge were performed. Symptoms of depression and anxiety were measured using the Hospital Anxiety and Depression Scale (HADS). Eighty-two percent of the subjects reported no anxiety or depression whatsoever, 11% reported anxiety, 2.5% depression and 4% reported both anxiety and depression. All respiratory symptoms, such as wheezing, breathlessness and nightly symptoms, were more common, at a statistically significant level, in participants who had depression and anxiety, even after adjusting for confounders (ORs 1.33-1.94). The HADS score was the most important determinant for nightly symptoms and attacks of breathlessness when at rest whereas bronchial responsiveness was the most important determinant for wheezing, and breathlessness when wheezing. The probability of respiratory symptoms related to HADS score increased with increasing HADS score for all respiratory symptoms. In conclusion, there is a strong association between respiratory symptoms and psychological status. There is therefore a need for interventional studies designed to improve depression and anxiety in patients with respiratory symptoms.

Body mass index change and atopic diseases are not always associated in children and adolescents

BACKGROUND

Several studies have suggested an association between the increasing prevalence of allergic diseases and dietary factors.

OBJECTIVE

To prospectively explore the association between changes in body mass index (BMI) and symptoms of asthma, rhinitis, rhinoconjunctivitis, and atopic dermatitis to find out whether an increase in BMI increases the risk of developing atopic diseases in adolescence.

METHODS

Comprehensive questionnaires and anthropometric measurements were applied in a random subsample of the International Study of Asthma and Allergies in Childhood phase II (1995-1996, 9 to 11 years of age) in Germany. Of these participants, 1,794 could be followed up in 2002 to 2003 in the Study on Occupational Allergy Risks (16 to 18 years of age). The associations between changes of BMI from baseline to follow-up and incident and persistent respiratory diseases and atopic dermatitis were assessed.

RESULTS

In logistic regression analyses, weight change in either direction was not statistically significantly associated with the incidence or persistence of any of the diseases of interest except for rhinitis. An increase in BMI was linked to an increased risk of incident rhinitis (odds ratio 1.9, 95% confidence interval 1.2-2.9).

CONCLUSION

These results indicate a nonsignificant trend between increased body weight and risk of atopic diseases. Aside from limitations owing to a small subgroup of obese participants and questionnaire-based asthma diagnosis, reasons might be related to an interaction between BMI and hormonal influences, age, and duration and severity of overweight. The results underline that BMI does not necessarily play a decisive role in the course of atopic diseases in all populations.

Associations of asthma with body mass index and adult weight change among reproductive age women

OBJECTIVE

To evaluate the cross-sectional relationship between asthma and pre-gravid body mass index (BMI), and to assess the risk of adult weight change among women with history of asthma diagnosed in childhood or adulthood, respectively.

STUDY DESIGN

Study participants were 3737 pregnant women enrolled in a cohort study. Information on history of asthma, pre-gravid BMI, adult weight change (difference between BMI at age 18 and pre-gravid BMI), and other sociodemographic characteristics was collected using interviewer-administered questionnaires. Pre-gravid BMI was categorized into lean (BMI < 18.5 kg/m(2)), overweight (BMI = 25-24.9 kg/m(2)), and obese (BMI ≥ 30 kg/m(2)). Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

Approximately 13.1% of study participants reported history of asthma. Compared with the reference group (BMI = 18.5-24.9 kg/m(2)), the odds of asthma was higher among overweight (OR = 1.51; 95% CI = 1.18-1.93) and obese (OR = 1.47; 95% CI = 1.06-2.03) women while it was lower among lean women (OR = 0.42; 95% CI = 0.21-0.84) (trend p-value <.001). Women who gained ≥20 kg compared with those who maintained their weight (±2.5 kg) had a 2.7-fold increased odds of asthma (95% CI = 1.02-7.00).

CONCLUSIONS

Overweight and obese women were more likely to have a history of asthma. Adult weight gain was positively associated with asthma diagnosis. Longitudinal studies designed to prospectively assess patterns of adult weight change in relation to asthma are warranted.

Airway responsiveness measured by forced oscillation technique in severely obese patients, before and after bariatric surgery

BACKGROUND

The influence of obesity on airway responsiveness remains controversial.

OBJECTIVE

This study was designed to investigate airway responsiveness, airway inflammation, and the influence of sleep apnea syndrome (SAS), in severely obese subjects, before and after bariatric surgery.

METHODS

A total of 120 non-asthmatic obese patients were referred consecutively for pre-bariatric surgery evaluation. Lung function, airway responsiveness to methacholine, exhaled nitric oxide measurement, and sleep studies were performed. Airway hyperresponsiveness (AHR) was defined as a 50% or greater increase in respiratory resistance measured using the forced oscillation technique in response to a methacholine dose ≤ 2000 μg. Forced expiratory volume in 1 second (FEV₁) was measured after the last methacholine dose. Airway responsiveness was reevaluated after weight loss in patients with a pre-surgery AHR.

RESULTS

AHR was found in 16 patients. The percent FEV₁ decrease or percent respiratory resistance increase in response to methacholine was related to baseline expiratory airflow (forced expiratory flow at 50%) (r = 0.26, p < .006 and r = 0.315, p = .0005, respectively) but not to body mass index (BMI) or exhaled nitric oxide. Both airway responsiveness parameters were significantly related to forced expiratory flow at 25-75%/forced vital capacity, a measure of airway size relative to lung size (r = 0.27, p < .005 and r = 0.25, p < .007, respectively). Sleep apnea was not significantly associated with AHR or airway inflammation. About 11 patients with AHR were reevaluated 18 months to 2 years after surgery, with no change in AHR associated with weight loss.

CONCLUSION

Airway responsiveness is not related to BMI or to SAS. AHR in severely obese patients might be related to distal airway obstruction or low relative airway size.

Usefulness of exhaled nitric oxide for diagnosing asthma

RATIONALE

A standard asthma diagnosis is made based on clinical history, reversibility of airway obstruction, and bronchial hyperresponsiveness. Fractional exhaled nitric oxide (FeNO) is a noninvasive airway inflammatory marker that has been suggested as a diagnostic tool for asthma. The aim of this study was to establish a FeNO cut-off value for asthma diagnosis.

METHODS

One hundred and fourteen consecutive adult patients (mean age 34 ± 13 years) reporting symptoms consistent with asthma, with normal spirometric parameters and a negative bronchodilator test, were included in the study. All underwent a methacholine challenge test following the five-breath dosimeter protocol. FeNO was measured with a portable device (NioxMino, Aerocrine AB, Sweden) just before the methacholine challenge. The sensitivity, specificity, and diagnostic performance of FeNO measurement were calculated.

RESULTS

Thirty-five out of the 114 patients (30.7%) were diagnosed with asthma. A positive methacholine challenge was associated with higher FeNO levels and with lower forced expiratory volume in one second (FEV(1)) at baseline. No correlation was found between methacholine provocative concentration causing a decrease of 20% in FEV(1) (PC(20)) and FeNO levels. A receiver-operating characteristic curve was constructed for FeNO levels (area under the curve [AUC]: 0.762; 95% confidence interval [CI]: 0.667-0.857; p < .001). The FeNO cut-off point with maximal specificity and sensitivity for asthma diagnosis was 40 ppb.

CONCLUSIONS

Patients with confirmed asthma showed higher FeNO levels. A cut-off value of 40 ppb was calculated as the most efficient for asthma diagnosis in our population. The use of FeNO measurement may be a helpful tool to rule out a diagnosis of asthma, especially in patients in whom a methacholine challenge is not feasible or available.