Relationship of non-specific airway hyperresponsiveness (AHR) to measures of peak expiratory flow (PEF) variability

The use of reliever medication in asthma: the role of negative mood and symptom reports

The aim of this study was to investigate the relationships between negative mood, the reporting of asthma symptoms, and the use of short-acting bronchodilators (reliever medication). Forty-two adult asthma patients completed a daily questionnaire over 7 consecutive days. The questionnaire measured negative mood and the number of symptoms patients associated with their asthma. The symptoms included those typical of asthma, as well as nonspecific somatic and distress symptoms. Subjects were also asked to record their daily use of reliever medication and their peak flow values. Data analysis demonstrated that even when controlling for lung function, both asthma symptom labeling and negative mood were related to reliever use. A mediation model suggested that negative mood leads patients to associate a wide range of nonspecific symptoms with their asthma, thereby altering the perception of the severity of the asthma, which in turn influences their use of reliever medication. The results of this study are discussed in relation to asthma self-management strategies.

Assessment of diurnal variability of peak expiratory flow in stable asthmatics

Five daily readings of peak expiratory flow (PEF) were obtained for three days on 100 patients with chronic stable asthma. The variability of PEF was calculated as the amplitude percent mean (A%M) from the readings obtained on the third day, and compared to previously reported data from 152 healthy Indian adults. Patients with severe asthma exhibited significantly higher A%M than patients with both mild and moderate asthma (p < 0.05), but there was considerable overlap across disease categories. The area under the receiver operating characteristic curve plotted to assess the performance of PEF variability as a discriminator in diagnosing asthma was 0.826, with best discrimination at a value of 12.5 (sensitivity 0.640, specificity 0.941). Using a cut-off value of 16.5 (as proposed earlier by us) improved specificity to 0.987 but reduced sensitivity to 0.510. Using a traditional cut-off of 20, specificity remained almost unchanged (0.993), but sensitivity dropped further to 0.440. Thus A%M>16.5 is a useful marker of bronchial asthma in epidemiological studies in India. However, its use in population screening, clinical diagnosis, or in the assessment of the severity of asthma in individual patients has serious limitations because of poor sensitivity.