Table 1

Summary of measurements

DomainInstrument/Indices
Outcomes
Respiratory morbidity2-week symptom recall. The primary outcome for aim 1 is maximum symptom days in the prior 2 weeks59–62 assessed at completion of home sampling visits, defined as the largest value among the following three variables: number of days with wheezing, tightness in the chest, or cough; number of nights with disturbed sleep as a result of breathing symptoms; and number of days on which the child had to slow down or discontinue play activities because of breathing symptoms
Composite Asthma Score Index (asthmatic children only): Assesses impairment, risk and level of controller therapy, graded per national asthma guidelines (EPR-3) across domains: day symptoms, night symptoms, controller treatment, lung function measurements and exacerbations65
Daily symptom diary: Catalogue of respiratory symptoms experienced for the duration of the sampling period
Lung functionPrimary: Spirometry (FEV1, FVC, FEF25-75, FEV1/FVC);
Forced oscillometry (R5, R20, R5-20, fres, AX5)
Household physical environment (primary exposures)
Household temperature, humidity, ventilation, particulates, NO2Indoor Environment Monitors: Awair-Omni weather stations for temperature, relative humidity, CO2, VOC and PM2.5; AlphaSense sensors with dataloggers using electrochemical (NO, NO2, CO2) sensors (OPC-N2; Harvard Mini-PEM). Mean daily levels, peaks, variances, and for PM2.5, also integrated levels over 7 days
Home Audit and Housing Scale Score51: Survey focused on housing types and characteristics. Specific indices derived from self-report and visual inspection, including ventilation, moulds, pests, smoking, and combustion by-products.
Household dust allergens and endotoxinBedroom Dust: Allergens: Der p1, Der f1, Mite Group 2, Bla g2, Fel d1, Can f1, Mus m1, Rat n1 (MARIA assay,56 Bio-Rad); endotoxin (enzyme immunoassay averages (log transformed; upper quartiles)58)
Time-activity logHourly Time-Activity Diary: Diary of activities performed in the home during the sampling periods, including child sleep time, cooking and cleaning activities
Household conditionsHouse Audit: Noise, light, shades, bedroom configuration base on interview and visual inspection66
Secondhand smokeUrinary Cotinine: ELISA (Abnova, Walnut, CA; sensitivity 1 ng/mL) and questionnaire
Neighbourhood physical environment (secondary exposures)
Neighbourhood walkability, poverty, disorder, social cohesion, crimeNeighbourhood Questionnaire: Includes neighbourhood safety (feeling safe walking in the neighbourhood)
Geographic Information System: Geocoding factors contributing to neighbourhood disadvantage and fragmentation (% vacant house units, owner-occupied housing, etc)67
Child characteristics (modifiers, confounders)
Atopy
(specific sensitisation)
Total IgE, Phadiatop with reflex allergen-specific IgE levels for positive results (ImmunoCAP, Phadia AB): House dust mite (Dermatophagoides pteronyssinus, Dermatophagoides farinae), cockroach (Blattella germanica), cat, dog dander, mouse urine, Aspergillus, Alternaria, Penicillium, Cladosporium sphaerospermum, grass pollen, tree pollen and short ragweed
Respiratory symptoms/asthma (prevalence, severity)International Study Of Asthma And Allergies In Childhood (ISAAC) asthma core questions: Score of ≥5 on the eight-item global wheezing questions has a sensitivity of 95% and specificity of 100% for identifying asthma68 69
Composite Asthma Score Index (asthmatic children only, detailed above)65
Paediatric sleep questionnaire70
Modified asthma control test71
RhinitisISAAC rhinitis core questions69 72 73
Respiratory illnessesSICAS healthcare utilisation and respiratory infections (last 12 months)74
AdiposityExam: height, weight (BMI percentiles)
General healthSICAS Medical History and Medications Questionnaire46
PROMIS Global Health 775 76
PROMIS Profile 2577
Patient Health Questionnaire-4 (PHQ-4)64
DemographicsParent-reported questionnaire
  • BMI, body mass index; FEF, forced expiratory flow; FEV1, forced expiratory volume in one second; FVC, forced vital capacity.