Reference equations for oscillometry and their differences among populations: a systematic scoping review

Abstract

Respiratory oscillometry is gaining global attention over traditional pulmonary function tests for its sensitivity in detecting small airway obstructions. However, its use in clinical settings as a diagnostic tool is limited because oscillometry lacks globally accepted reference values. In this scoping review, we systematically assessed the differences between selected oscillometric reference equations with the hypothesis that significant heterogeneity existed between them. We searched bibliographic databases, registries and references for studies that developed equations for healthy adult populations according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A widely used Caucasian model was used as the standard reference and compared against other models using Bland–Altman and Lin's concordance correlational analyses. We screened 1202 titles and abstracts, and after a full-text review of 67 studies, we included 10 in our analyses. Of these, three models had a low-to-moderate agreement with the reference model, particularly those developed from non-Caucasian populations. Although the other six models had a moderate-to-high agreement with the standard model, there were still significant sex-specific variations. This is the first systematic analysis of the heterogeneity between oscillometric reference models and warrants the validation of appropriate equations in clinical applications of oscillometry to avoid diagnostic errors.

Spirometry and respiratory oscillometry: Feasibility and concordance in schoolchildren with asthma

“…As a result, it is unclear whether the reference values should be specific for different RO systems or even for each commercial equipment, or if they should be different for different ethnic groups. Most of the reference values published to date, in children and adults, have been obtained with IOS systems, and are rather conflicting 23 . One study in children compared different reference values obtained by IOS to identify poorly controlled asthma, 24 and concluded that the most suitable for it would be the Mexican ones of Gochicoa‐Rangel 25 .…”

“…Most of the reference values published to date, in children and adults, have been obtained with IOS systems, and are rather conflicting. 23 One study in children compared different reference values obtained by IOS to identify poorly controlled asthma, 24 and concluded that the most suitable for it would be the Mexican ones of Gochicoa-Rangel. 25 But the same authors also found a good concordance in normal/abnormal classification of RO results using various reference values, and regardless of the ethnic origin of the population from which those values were obtained.…”

Oscillometry in Lung Function Assessment: A Comprehensive Review of Current Insights and Challenges

“…Such standards should be adaptable to different healthcare settings, accommodating variations in equipment and patient populations. The ultimate goal is to provide clinicians with a common foundation for conducting oscillometry tests, leading to more accurate and comparable results [ 59 ].…”

Reply to Salvi and Ghorpade: Z-Scores or Fixed Cutoff Values to Interpret Oscillometry: Opportunities from the LEAD Study

“…The suggestion to explore the possibility of using fixed cutoffs for oscillometry parameters is intriguing, as it could simplify the use of oscillometry under the assumption that changes caused by anthropometric factors are negligible compared with those attributed to pathology. However, all previous work on reference equations reported the dependence of oscillometry data on anthropometric variables, especially height in healthy subjects ( 2 ), even if such dependence is less marked than for spirometry. Under the condition that residuals of the normative regression equations are approximately normally distributed, z -scores can still reflect the distribution probability of the measured value, as also reported by Liang and colleagues ( 3 ).…”