Assessment of a bronchodilator response in preschoolers: a systematic review

Abstract

ABSTRACTBackgroundA bronchodilator response (BDR) can be assessed in preschool-aged children using spirometry, respiratory oscillometry, the interrupter technique, and specific airway resistance, yet a systematic comparison of BDR thresholds across studies has not been completed.MethodsA systematic review was performed on all studies up to May 2023 measuring a bronchodilator effect in children 2-6 years old using one of these techniques (PROSPERO CRD42021264659). Studies were identified using MEDLINE, Cochrane, EMBASE, CINAHL via EBSCO, Web of Science databases, and reference lists of relevant manuscripts.ResultsOf 1224 screened studies, 43 were included. Over 85% were from predominantly Caucasian populations, and only 22 studies (51.2%) calculated a BDR cut-off based on a healthy control group. Sample sizes ranged from 25-916. Only two studies (4.6%) adhered to formal recommendations for study design: at least 300 subjects, randomised for placebo response testing in healthy children, and incorporated within-session and between-session test repeatability. A relative BDR was most consistently reported by the included studies (95%) but varied widely across all techniques. A variety of statistical methods were used to define a BDR. The highest BDR feasibility was reported with oscillometry techniques in this age group.ConclusionA BDR in 2-6-year-olds cannot be defined based on the reviewed literature due to inconsistent methodology and cut-off calculations. Precise and feasible evaluation of lung function in young children is crucial for early detection and intervention of airway diseases. A standardised approach is required to develop robust BDR thresholds.