Search strategy | Definition | Rules to operationalise |
Population ‘Asthma’ | Children aged 5–12 years with doctor-diagnosed asthma, across all severities and degrees of control | We included studies with a wider range of ages if results for children aged 5–12 years were reported separately or if more than 50% of the children were within this age range. We excluded:
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Any setting | ||
Outcome ‘Exacerbations/Attacks’ | Severe asthma attacks as defined by the ATS/ERS Task Force14: asthma symptoms and/or objective evidence of obstruction outside the normal variation for the patient necessitating (A) a short course (at least 3 days) of oral corticosteroids, and/or (B) a hospitalisation or emergency department visit requiring systemic corticosteroids | We excluded studies assessing risk factors for:
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Risk factors/predictors | Any feature of the child, family or social context, clinical history, examination finding or test routinely available in clinical practice which increased the propensity of the child to have an asthma attack | We excluded:
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Any routine clinical care (eg, attendance (or not) at routine reviews) and disease-related behaviours (eg, adherence (or not) to preventer medication) | We excluded:
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Study designs | Cohort, case-control studies and cross-sectional studies (but not case studies and case series) | We included controlled trials if they included an analysis that provided an estimate of risk of an attack (eg, cohort or cross-sectional studies from baseline data). |
ATS, American Thoracic Society; ERS, European Respiratory Society; GINA, Global Initiative for Asthma; ICU, intensive care unit.