Agertoft 1998.

Study characteristics
Methods	Design: single‐blind parallel‐group randomised controlled trial Duration: 2 weeks Setting: 1 outpatient clinic in Denmark Trial registration: not reported
Participants	Population: 72 children with asthma randomised to hospital and home training (n = 36) or hospital training alone (n = 36) Age: children aged 3 to 5 years; mean age 54 months (range 36 to 71 months) Baseline asthma severity: not reported Inclusion criteria: preschool children aged 3 to 5 years. All had bronchial asthma and were receiving inhaled anti‐inflammatory therapy through a pMDI and spacer Exclusion criteria: children with acute wheeze Percentage withdrawn: 0% of participants withdrew from the intervention group and 3% from the control group Other allowed medication: All children continued their regular antiasthma therapy throughout the course of the study
Interventions	Intervention summary: instructional video followed by instructional pamphlet contained in the commercially available Turbuhaler package. Intervention group children then received individual training from a nurse and a placebo inhaler to practice with at home over the next 2 weeks Control summary: instructional video followed by instructional pamphlet contained in the commercially available Turbuhaler package
Outcomes	Outcomes measured: lung function measures: peak inspiratory flow (PIF) and inspiratory vital capacity (IVC). Peak expiratory flow rate (PEF), forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) were measured "for demographic purposes only" Technique assessment method used: PIF was used as a measure of inhaler technique
Notes	Type of publication: single peer‐reviewed journal article Funding: not reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	"At study entry, the children were stratified by age and randomly allocated to one of two study groups". It not clear how the sequence was generated for randomisation after stratification by age
Allocation concealment (selection bias)	Unclear risk	No details
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Children, caregivers and personnel could not be blinded owing to nature of intervention. However, given the young age of children and the objective nature of the outcome measures (lung function), it is unlikely that knowledge of group allocation had an impact on their performance, beyond the impact intended by the intervention
Blinding of outcome assessment (detection bias) All outcomes	Low risk	The trial is described as single‐blind. "The investigator conducting all inspiratory and expiratory lung function testing was unaware of the level of training received by each child after the initial basic clinic training". In addition, lung function measures are relatively objective and are not at high risk of detection bias
Incomplete outcome data (attrition bias) All outcomes	Low risk	Only 1 child in the control group was withdrawn from the trial by parents
Selective reporting (reporting bias)	Unclear risk	No prospective trial registration identified. Baseline characteristics table missing, so unable to assess baseline imbalances objectively, although text states that groups were balanced. All outcomes listed in Methods reported in the text
Other bias	Low risk	None noted