Accuracy of spirometry for detection of asthma: a cross-sectional study

Blood eosinophils, FeNO and small airways dysfunction in predicting airway hyperresponsiveness in patients with asthma-like symptoms

PURPOSE

In patients with suspected asthma and no airflow limitation in spirometry, methacholine challenge testing (MCT) for airway hyperresponsiveness (AHR) is an option of documenting variable airflow limitation. The goal of the study was to assess the ability of blood eosinophils, fractional concentration of exhaled nitric oxide (FeNO) and distal airways function to discriminate patients with AHR from those with normal airway responsiveness (AR).

METHODS

We analyzed baseline data from 42 participants who underwent MCT because of asthma-like symptoms and no airflow limitation in spirometry.

RESULTS

Eosinophil count was higher among participants with borderline AHR comparing to those with normal AR (340 cells/µL, IQR 285-995 vs. 125 cells/µL, IQR 75-180, post-hoc p = 0.041). FeNO and percent predicted of functional residual volume (FRC%pred) were higher in participants with moderate-marked AHR compared to those with normal AR (40 ppb, IQR 30.5-100.5 vs. 18 ppb, IQR 13-50, post-hoc p = 0.008; 140.1%±17.0% vs. 107.3%±20.7%, post-hoc p < 0.001, respectively). Percentage predicted of the maximal expiratory flow at 25% of the forced vital capacity (MEF₂₅%pred) was lower in participants with mild AHR and borderline AHR compared to those with normal AR (72.9%±16.9% vs. 113.0%±36.8%, post-hoc p = 0.017; 73.3%±15.9% vs. 113.0%±36.8%, post-hoc p = 0.045; respectively). Level of AHR correlated with eosinophil count, FeNO, MEF₂₅%pred, forced expiratory flow between 25% and 75% of vital capacity (FEF_25-75%pred), FRC%pred and specific airway resistance (sR_aw).

CONCLUSIONS

Blood eosinophils, FeNO and small airways dysfunction markers are related to the level of AR to methacholine in patients with asthma-like symptoms and no airflow limitation in spirometry.

The Association Between Beliefs and Adherence to Inhaled Controller Medication Among Older Adults with Asthma: A Cross-Sectional Study in Primary Care

BACKGROUND

While illness perceptions and medication beliefs have been shown to be associated with inhaled corticosteroid (ICS) adherence in younger adults with asthma, their impact on older adults is less understood. This study aimed to determine the prevalence of ICS adherence among older Asian adults and to assess the association between ICS adherence, illness perceptions and medication beliefs.

METHODS

A questionnaire survey on older multi-ethnic Asian patients, aged ≥60 years, with physician-diagnosed asthma, was conducted in two Singapore public primary care clinics. The scores of the Medication Adherence Report Scale for asthma (MARS) were computed to determine the adherence to ICS alone or in combination with LABA. Illness perceptions and medication beliefs were assessed by the scores from the Brief-Illness Perception Questionnaire (B-IPQ) and Beliefs about Medications Questionnaire (BMQ), respectively. Logistic regression analyses were used to identify factors associated with ICS adherence.

RESULTS

Analyses of 323 participants (57% males; Chinese 73.7%, Malay 12.7%, Indian 12.4%; mean age 71.5 years) showed that 40.9% of them had good adherence to ICS (mean MARS score≥4.5). Good adherence to ICS was associated with perception of asthma as a chronic illness (OR=1.22; 95% CI=1.10-1.35; p<0.001), belief of ICS as an essential medication (2.67; 1.76-4.06; p<0.001) and fewer concerns about its use (0.39; 0.26-0.60; p<0.001). Patients on combined ICS-LABA therapy had higher adherence (2.50; 1.41-4.44; p=0.02) than those on ICS monotherapy.

CONCLUSION

Four in ten older patients with asthma were adherent to ICS. Perception of medication necessity, chronicity of illness, concerns and use of ICS-LABA medication were associated with adherence.