J. Gamble

Predictors of therapy resistant asthma: outcome of a systematic evaluation protocol

Background: It has been suggested that asthmatic subjects with persisting symptoms despite adequate maintenance therapy should be systematically evaluated to identify factors contributing to poor control. The aims of this study were to examine the prevalence of these factors in a cohort of sequentially referred poorly controlled asthmatics, and to determine if any factor or combination of factors predicted true therapy resistant asthma (TRA). Methods: Patients were evaluated using a systematic evaluation protocol including induced sputum analysis, psychiatric assessment, ear, nose and throat examination, pulmonary function testing, high resolution CT scan of the thorax, and 24 hour dual probe ambulatory oesophageal pH monitoring; any identified provoking factor was treated. Asthma was managed according to BTS guidelines. Results: Of 73 subjects who completed the assessment, 39 responded to intervention and 34 had TRA. Subjects with TRA had a greater period of instability, a higher dose of inhaled steroids at referral, more rescue steroid use, and a lower best percentage forced expiratory volume in 1 second (FEV1%). Oesophageal reflux, upper airway disease, and psychiatric morbidity were common (57%, 95%, 49%, respectively) but were not more prevalent in either group. Using multivariate logistic regression analysis, inhaled steroid dose >2000 μg BDP, previous assessment by a respiratory specialist, and initial FEV1% of <70% at referral predicted a final diagnosis of TRA. Conclusions: In poorly controlled asthmatics there is a high prevalence of co-morbidity, identified by detailed systematic assessment, but no difference in prevalence between those who respond to intervention and those with TRA. Targeted treatment of identified co-morbidities has minimal impact on asthma related quality of life in those with therapy resistant disease.

Relationship between lung function and asthma symptoms in patients with difficult to control asthma.

Several studies have demonstrated a poor relationship between measures of asthma control and lung function in patients with asthma. We sought to examine this relationship in a cohort of difficult to control asthmatics attending a hospital outpatient clinic. FEV1% and asthma control scores (ACSs) were measured at the first clinic visit and at a follow-up visit. A total of 59 patients took part in the study. At the initial visit, FEV1% correlated with limitation of activity (p = 0.002), shortness of breath (p = 0.02), wheezing (p = 0.029), and ACS (p = 0.014). However, at follow-up, there was no correlation between FEV1% and any measured index of asthma control. When patients with severe fixed airflow obstruction were excluded from the analysis (n = 16), FEV1% at follow-up became significantly correlated with night waking (p = 0.02), wheezing (p = 0.05), and ACS (p = 0.036). The improvement in asthma control score at follow-up was significantly and strongly associated (r = 0.51 for total asthma control, p < 0.001) with the improvement in lung function in patients without severe fixed airflow obstruction. Lung function was not associated with any measure of asthma control in patients with severe fixed airflow obstruction. FEV1% correlates well with asthma symptoms in difficult asthma patients with poor control but not when control improves. This loss of relationship is due to subjects with severe fixed airflow obstruction where good subjective control does not exclude the presence of significant obstruction. How severe fixed airflow obstruction should be prevented, delayed, or managed in asthma requires further research.

Assessment of impairment in health-related quality of life in patients with difficult asthma: psychometric performance of the Asthma Quality of Life Questionnaire.

Objective and background:  To understand the effects of asthma and its treatment and to draw accurate conclusions with respect to different management programmes, including clinical trials. In more severe asthmatics, it is imperative that the health‐related quality of life (HRQL) be measured accurately and validly. This study had a twofold objective: (i) to examine the psychometric characteristics of the Asthma Quality of Life Questionnaire (AQLQ) in patients with difficult asthma, and (ii) to explore to what extent suffering from asthma affects the HRQL in patients with difficult asthma.