| Methods |
Country: Netherlands
Setting: community
RCT; cluster |
| Participants |
476 children seen to be at high risk of asthma recruited during the prenatal period |
| Interventions |
Intervention: 3 home visits (2 prenatal and 1 postnatal) with recommendations to reduce 4 main environmental exposures of mite allergens, pet allergens, food allergens, and passive smoking prenatally and postnatally
Control: usual care |
| Outcomes |
Parent report of child ETS exposure
Maternal CO
Child IgE
Tidal airway resistance and lung function
Allergen measures |
| Type of intervention |
Well‐child (peripartum) |
| Notes |
Retention: 443/476 (93%) |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Random sequence generation (selection bias) |
Unclear risk |
Prerandomisation; no further information provided |
| Allocation concealment (selection bias) |
Unclear risk |
"To prevent contamination... the prerandomisation was performed in clusters, taking into account the post (zip) code of the domicile of the recruited family in
combination with the location of the general practice the family attended. Once a general practice was allocated, every family subsequently recruited in that practice was allocated automatically to the same group." |
| Incomplete outcome data (attrition bias)
All outcomes |
Low risk |
93% retention; similar number completed follow‐up in both groups (222/242 intervention, 221/234 control); attrition and ITT analyses performed |
| Blinding of outcome assessment (detection bias)
All outcomes |
High risk |
Self‐report only: "reporting bias cannot be excluded as an explanation for the decrease in asthma‐like symptoms in the intervention group at age 2 yrs." |
