The 'clinically significant' bronchodilator responsiveness (BDR) in children: a comparative study between six definitions of scholarly societies and a mini-review

Correlation of spirometry indices to chest radiology in the diagnosis of chronic airway disease among regional and rural Indigenous Australians

BACKGROUND

The majority of Indigenous Australians reside in non-urban locations, with reduced access to chest radiology such as computed tomography (CT). Spirometry and chest X-ray (CXR) may be used in the absence of CT; however, the correlation of spirometry indices to CT-defined chronic airway diseases (i.e. chronic obstructive pulmonary disease (COPD) and bronchiectasis) compared with CXR among Indigenous people is sparsely reported.

AIM

To evaluate spirometry indices against CXR and CT findings among adult Indigenous Australians.

METHODS

Indigenous patients who had undergone a spirometry test between 2012 and 2020 and had a CXR or chest CT scan assessed for the presence (+ )/absence (- ) of airway diseases were included in this study.

RESULTS

Of 643 patients (57% female, 31% remote/very remote), 364 (57%) had CT and CXR available. Patients who were 'CT- and CXR- ' for airway diseases (48%) recorded a mean FVC, FEV1 and FEV1 /FVC of 61%, 59% and 0.76 compared to 57%, 49% and 0.66 in the 'CT+ and CXR- ' group and 53%, 39% and 0.58 in the 'CT+ and CXR+ ' group. CXR showed sensitivity (44%) and specificity (88%), while spirometry showed 62% and 77% compared to CT. Spirometry demonstrated predominately restrictive impairment among 'CT- and CXR- ' and mixed/obstructive impairment among 'CT+ and CXR- ' and 'CT+ and CXR+ ' groups.

CONCLUSION

Indigenous Australians tend to demonstrate restrictive impairment in the absence of radiological evidence of airway disease. However, in the presence of airway disease, combinations of mixed and obstructive impairments were common. Obstructive impairment shows greater sensitivity for identifying COPD than that shown by CXR; however, CXR shows greater specificity. Hence, spirometry in conjunction with chest radiology should be utilised to aid in the assessment of airway diseases in this population.

Bronchodilator response does not associate with asthma control or symptom burden among patients with poorly controlled asthma

PURPOSE

The purpose of this study was to determine how four different definitions of bronchodilator response (BDR) relate to asthma control and asthma symptom burden in a large population of participants with poorly controlled asthma.

PROCEDURES

We examined the baseline change in FEV1 and FVC in response to albuterol among 931 participants with poorly controlled asthma pooled from three clinical trials conducted by the American Lung Association - Airways Clinical Research Centers. We defined BDR based on four definitions and analyzed the association of each with asthma control as measured by the Asthma Control Test or Asthma Control Questionnaire, and asthma symptom burden as measured by the Asthma Symptom Utility Index.

MAIN FINDINGS

A BDR was seen in 31-42% of all participants, depending on the definition used. There was good agreement among responses (kappa coefficient 0.73 to 0.87), but only 56% of participants met all four definitions for BDR. A BDR was more common in men than women, in Blacks compared to Whites, in non-smokers compared to smokers, and in non-obese compared to obese participants. Among those with poorly controlled asthma, 35% had a BDR compared to 25% of those with well controlled asthma, and among those with a high symptom burden, 34% had a BDR compared to 28% of those with a low symptom burden. After adjusting for age, sex, height, race, obesity and baseline lung function, none of the four definitions was associated with asthma control or symptom burden.

CONCLUSION

A BDR is not associated with asthma control or symptoms in people with poorly controlled asthma, regardless of the definition of BDR used. These findings question the clinical utility of a BDR in assessing asthma control and symptoms.

The Prevalence of Bronchodilator Responsiveness "Asthma" Among Adult Indigenous Australians Referred for Lung Function Testing in the Top End Northern Territory of Australia

Background

Among Indigenous Australians, studies examining the clinical significance of airway bronchodilator responsiveness (BDR) are limited. In this retrospective study, we examined the nature of underlying lung disease in adult Indigenous patients with BDR referred for lung function testing (LFT) in the Top End Health Service region of the Northern Territory of Australia.

Methods

Presence or absence of BDR as per usual (FVC or FEV₁ change pre to post ≥12% and ≥0.2L) and updated (2021 ">10% predicted) ATS/ERS criteria among Indigenous and non-Indigenous Australians was determined. The radiological findings in the Indigenous study participants with and without BDR were next assessed for the presence of underlying chronic airway/lung disease.

Results

We found that 123/742 (17%) Indigenous and 578/4579 (13%) non-Indigenous patients had a significant BDR. Indigenous patients with BDR were younger (mean difference 7 years), with a greater proportion of females (52 vs 32%), underweight (15 vs 4%) and current smokers (52 vs 25%). Indigenous patients with BDR displayed lower LFT values, and a higher proportion exhibited FVC BDR compared to non-Indigenous (34 vs 20%). Almost half (46%) of Indigenous patients with BDR had evidence of COPD and/or bronchiectasis on radiology. Adjusting for the presence of radiologic or spirometric evidence of COPD, the presence of BDR was similar between Indigenous and non-Indigenous patients (5-8 vs 7-11%), irrespective of which BDR criteria was used.

Conclusion

BDR was higher overall among Indigenous in comparison to non-Indigenous patients; however, a significant proportion of Indigenous patients demonstrating BDR had evidence of underlying COPD/bronchiectasis. This study highlights that although presence of BDR among Indigenous people may indicate asthma, it may also be observed among patients with COPD/bronchiectasis or could represent asthma/COPD/bronchiectasis overlap. Hence, a combination of clinical history, LFT and radiology should be considered for precise diagnosis of lung disease in this population.

Is Bronchodilation Testing Routinely Useful in All Asthmatic Children?

Background: The reversibility of bronchial obstruction is needed to diagnose asthma. Bronchodilation (BD) testing is, therefore, used in asthma work-up. This study explored the benefit of performing BD testing in asthmatic children without bronchial obstruction. Methods: The study included 60 subjects with asthma and normal lung function, 13 (21.7%) females and 47 (78.3%) males; the mean age was 11.5 years, 26 were adolescents, and 34 were children. Lung function, symptoms, use of asthma medications, type 2 inflammation, and asthma control were assessed in all subjects. Results: Eleven (18%) subjects positively responded to BD testing. Fifty-five percent of subjects were uncontrolled based on Global Initiative for Asthma (GINA) criteria. The multivariate analysis identified 2 factors associated with a positive response to BD testing: FEV₁ [odds ratio (OR) = 0.91) and ACT (OR = 0.79). Conclusions: This study showed that BD testing could give additional helpful information in clinical practice. In addition, uncontrolled asthma, based on GINA criteria, was prevalent in children with normal lung function.

The role of bronchodilation testing in children and adolescents with asthma in clinical practice

The change in forced expiratory volume in 1 s (FEV₁) in response to a bronchodilator (ΔFEV₁) is a diagnostic tool. Moreover, bronchodilation testing may give clinically relevant outcomes beyond diagnostic purposes. The present study aimed, therefore, to investigate the nationwide role of bronchodilation testing in daily practice. The study included 280 subjects, 202 (72.1%) males and 78 (27.9%) females; the mean age was 11.6 years. Notably, 67 (24%) children had bronchial reversibility (BDR). Age, initial FEV₁, FEV₁/FVC, and FVC were significantly associated with BDR (OR 1.16, 1.66, 0.71, and 0.67, respectively). Interestingly, 39 (58.2%) children with BDR had no bronchial obstruction. In conclusion, the BDR is usually associated with low values of the lung function parameters, even if within the normal ranges.