Horner 2008.

Methods	Included as outcome evaluation Study design: clustered parallel‐group design with schools selected as the unit of randomisation Setting: elementary schools in the USA; 10 treatment and 8 attention control schools Period: each of the participating school districts participated for 1 academic year, and the whole project spanned 2003 to 2006 academic years. Analysis occurred over 12 weeks of the academic year from study enrolment to 6 weeks post intervention
Participants	Eligible sample frame: 541 families of children were invited to participate Randomised: 183 pupils were randomised: 101 into treatment group and 82 into control group Completed (intervention): 163 pupils completed the trial Inclusion criteria: students were eligible for participation in the study if they had doctor‐diagnosed asthma, had experienced asthma symptoms in the previous 12 months, had no other significant comorbidity that would preclude participation in classes, spoke either English or Spanish, and were enrolled in grades 2 to 5 Exclusion criteria: not reported Baseline characteristics Age of children: mean age, 8.78 years Ethnicity: within the sample, 47% were Mexican American, 30% white, 22% African American, and 1% other Socio‐economic status: not reported Gender: 108 male; 75 female Asthma status: not reported
Interventions	Intervention: the curriculum presented a 7‐step asthma self‐management plan Control: the attention‐control group mirrored the treatment group and received education on health promotion topics appropriate for children Intensity: 16 sessions, each for 15 minutes Instructor: 18 lay health educators Theoretical framework: the asthma health education model that informed the study was adapted from Bruhn's theoretical model of asthma management Parental engagement: not reported Child satisfaction: not reported Timing of intervention in school day: lunch breaks
Outcomes	Extractable outcomes were collected for: Hospitalisation Withdrawal
Notes	Funding source: not reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Study authors reported: "schools were randomised through a simple coin toss at a summer meeting held with elementary school principals"
Allocation concealment (selection bias)	High risk	Risk that concealment of allocation was breached
Blinding of participants and personnel (performance bias) All outcomes	High risk	Study authors reported: "Because the participants could not be blinded to their treatment condition, this information was disclosed to parents during this first telephone call"
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not assessed by study authors
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Missing outcome data roughly balanced across intervention and control groups, with similar reasons for missingness and study authors reporting: "Comparing baseline scores of those who dropped out of the study with those who were retained (i.e. completers) showed no significant differences in terms of demographic or study variables"
Selective reporting (reporting bias)	Low risk	No evidence of selective reporting
Other bias	Low risk	Missingness ‐ low risk ‐ strategies implemented for missingness (which accounted for less than 10% of the sample) described as follows: "Missing items were handled by substituting the participant's mean score for the missed item in those cases where fewer than 10% of the items were missing for a scale. In this study, there were no instances of more than 10% of missed items for a scale" Baseline imbalance ‐ low risk ‐ comparing groups at baseline on study measures revealed no significant differences between groups except for asthma severity, which was greater in the treatment group Risk of contamination ‐ low ‐ schools were the unit of randomisation, lowering the potential for contamination
Transparent and clearly stated aims	Unclear risk	N/A
Explicit theories underpinning and/or literature review	Unclear risk	N/A
Transparent and clearly stated methods and tools	Unclear risk	N/A
Selective reporting	Unclear risk	N/A
Harmful effects	Unclear risk	N/A
Population and sample described well	Unclear risk	N/A
Continuous evaluation	Unclear risk	N/A
Evaluation participation equity and sampling	Unclear risk	N/A
Design and methods overall approach	Unclear risk	N/A
Tools and methods of data collection reliable/credible	Unclear risk	N/A
Tools and methods of data analysis reliable/credible	Unclear risk	N/A
Performance bias/neutrality/credibility/conformability	Unclear risk	N/A
Reliability of findings and recommendations	Unclear risk	N/A
Transferability of findings	Unclear risk	N/A
Overall risk of bias of process evaluation	Unclear risk	N/A