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Standardized IOS Reference Values Define Peripheral Airway Impairment-Associated Uncontrolled Asthma Risk Across
Stanley P Galant1, William Fregeau2, Neil Pabelonio2
1Breathmobile Department, Children's Hospital of Orange County, Orange, Calif; Department of Pediatrics, University of California Irvine, Irvine, Calif.
Insights
Impulse oscillometry (IOS) identifies peripheral airway impairment (PAI) and risk of uncontrolled asthma in children. Standardized IOS reference values are clinically relevant across ethnicities, offering reliable cutoff points for diagnosis.
Area of Science:
- Pediatric Pulmonology
- Respiratory Physiology
- Diagnostic Tools
Background:
- Impulse oscillometry (IOS) is clinically useful for identifying peripheral airway impairment (PAI) but lacks universal acceptance.
- Variable cutoff points and perceived irrelevance of reference values in diverse populations hinder widespread adoption.
Purpose of the Study:
- To establish the relationship between PAI using standardized IOS reference values and uncontrolled asthma.
- To assess the interchangeability of Hispanic and white reference algorithms for IOS.
Main Methods:
- Established IOS reference values (upper/lower limits of normal) using published algorithms in Hispanic and white children.
- Compared PAI in uncontrolled vs. controlled asthma groups and analyzed odds ratios for IOS measures (R5, R5-R20, AX, X5).
- Determined algorithm interchangeability using intraclass correlation coefficients.
Main Results:
- Uncontrolled asthma was significantly associated with greater PAI and higher frequency of PAI (P < .05).
- Odds of uncontrolled asthma increased with PAI across all IOS measures (P < .001), especially X5 (ORs 2.70-11.01).
- Good to excellent agreement (>70%) was found between Hispanic and white algorithms, except for R5-R20 (<70%).
Conclusions:
- PAI, defined by IOS reference values, is consistently linked to uncontrolled asthma risk in children, independent of ethnicity.
- Standardized IOS reference values provide clinically relevant, accessible cutoff points for clinicians across diverse populations.
- Peripheral airway markers (e.g., X5), not central airway markers (R20), are key indicators of uncontrolled asthma risk.
Background:
Although clinically useful in identifying peripheral airway impairment (PAI), impulse oscillometry (IOS) has not received universal acceptance. This may be due to variable cutoff points, and the perception that available standardized reference values may not be clinically relevant in all populations.
Objective:
To establish the relationship between PAI, based on standardized IOS reference values, and uncontrolled asthma as well as interchangeability between Hispanic and white reference algorithms.
Methods:
IOS reference values were established for upper and lower limits of normal (>95th and <5th percentile, respectively) using published algorithms in Hispanic and white children. Values exceeding normal limits (PAI) were compared in those uncontrolled and controlled for significance of differences. Probability estimates and odds ratio of uncontrolled asthma were determined for R5, R5-R20, AX, and X5 using adjusted generalized estimating equation analyses. Intraclass correlation coefficients determined interchangeability of Hispanic and white reference algorithm values.
Results:
Those with uncontrolled asthma had significantly greater PAI and a higher frequency of PAI than those well controlled (P < .05), whereas odds of uncontrolled asthma increased with increasing PAI (P < .001) for all IOS measures, particularly for X5, where odds ratios ranged from 2.70 to 11.01.There was good to excellent (>70%) agreement between Hispanic and white algorithms, except for R5-R20 (<70%).
Conclusions:
PAI, defined by IOS reference values, not central airway markers (R20), is consistently related to the risk of uncontrolled asthma. This is true whether using Hispanic or white reference algorithms. Thus, standardized reference values in children offer the clinician readily available IOS cutoff points that are clinically relevant across ethnicity.
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