Impulse Oscillometry Effective Detecting Non-Controlled Asthma

Researchers have previously confirmed impulse oscillometry (IOS) can be used to detect asthma control, but the technique has not fully been vetted in adult populations.

In new data presented virtually during the European Respiratory Society (ERS) 2020 International Congress this week, a team, led by Warawut Chaiwong, Chiang Mai University, assessed the diagnostic ability of impulse oscillometry for distinguishing between not well-controlled and well-controlled asthmatic patients.

IOS is a simple, noninvasive method allowing the evaluation of lung function through the measurement of both airway resistance and airway reactance.

The impulse oscillometry is currently a complementary approach to assessing asthma controls. However, the majority of studies targeted children, meaning the impulse oscillometry values for detection of asthma control in adults is still unknown.

In the cross-sectional study, the investigators examined patients between July 2019 and May 2020 at a lung health center in Chiang Mai, Thailand, performing IOS and spirometry on all participants. The study included patients with clinically diagnosed-asthma subjects at least 20 years old with stable disease for at least 6 weeks, a history of clinically diagnosed-asthma, controller medication for at least 12 weeks, a history of non-smoking or ex-smoking less than 5 packs per year.

The team excluded patients with abnormal spirometry results from the trial.

The investigators defined not well-controlled asthma in accordance with the Global Initiative for Asthma (GINA) guideline, along with an asthma control test score of at least 19. The research team also plotted a Receiver Operating Characteristic (ROC) curve to predict those with not well-controlled by area under the ROC (AUROC) and 95% confidence intervals.

The study included a total of 135 clinical diagnosed-asthma patients with a mean age of 53.4±15.8 years old. Of this patient population, 83 (61.5%) were female. The researchers also enrolled 23 healthy age and gender matched subjects as the control group.

The team included IOS parameters of heterogeneity of resistance at 5 Hz (R5) and resistance at 20 Hz (R20) (R%-R20), frequency resonance (Fres), and area under reactance (AX), which demonstrated excellent overall accuracy relative to the detection of not well-controlled asthma with an AUROC ranging from 0.910-0.920.

The values of R5-R20 ≥ 1.00 cmH2O/L/s represented the highest AUROC of 0.87, with a sensitivity of 89.1% and a specificity of 84.3% for the detection of not well-controlled asthma.

“IOS is a valuable tool for detection of not well-controlled asthma,” the authors wrote. “It may be used for assessment level of asthma control in adult asthma subjects.”

Genotype-based asthma controller prescribing may provide a significant improvement on primary clinical care of young patients than standard care, according to another ERS study.

At 12 months, genotype-based treatment was associated with a 0.16-point improvement (95% CI, 0.00-0.31; P = .049) in AQLQ versus standard therapy . Among pediatric patients with 2 copies of the altered beta-2 receptor gene, however, quality of life score was 0.42 improved versus standard care (95% CI, 0.02-0.81; P =.041).

The study, “The roles of impulse oscillometry in detection of asthma control level,” was published online by ERS 2020.