Meklin 2005a.
Methods | Controlled before‐after study | |
Participants | School children (7 to 13 yrs) in a mould‐damaged school (before repairs 414 pupils and 408 after repairs), were compared to children (7 to 14) in a non‐damaged school (208 pupils in the beginning and 238 in the final survey) in Finland | |
Interventions | Extensive renovation of the school building: structures were opened and renewed, land‐drains, drain‐, heating and water pipes were renewed, all coating materials were renewed, ventilation was installed, alteration from natural ventilation to mechanical exhaust and air supply. A thorough cleaning of the school | |
Outcomes | Buildings: self reported draft, insufficient ventilation, humid indoor air, mould odour, other unpleasant odour, dust or dirt, airborne bacteria and fungi Participants: self reported respiratory and asthma‐related symptoms |
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Notes | Results are presented in 2 different articles | |
Risk of bias | ||
Bias | Authors' judgement | Support for judgement |
Blinding of participants and personnel (performance bias) All outcomes | High risk | Not blinded |
Blinding of outcome assessment (detection bias) All outcomes | High risk | Not blinded |
Unplanned subgroup analyses (16) | Unclear risk | No data dredging |
Follow‐up (17) | Low risk | Follow‐up time up to 5 years |
Compliance (19) | Unclear risk | Compliance unclear |
Valid outcome measures (20) | Unclear risk | Questionnaire of subjective symptoms |
Selection bias (population) (21) | High risk | Participants and controls were from the same population but in the fully repaired school the attention to the problems seemed to be greater than elsewhere |
Selection bias (time) (22) | Low risk | The questionnaires were sent to the intervention and control group at the same time |
Random sequence generation (selection bias) | High risk | Not done |
Allocation concealment (selection bias) | High risk | Not done |
Adjustment for confounding (25) | Low risk | Age and prevalence of smoking was reported |
Incomplete outcome data (26) (attrition bias) | Low risk | Loss to follow‐up reported |