Domain | Instrument/Indices |
Outcomes | |
Respiratory morbidity | 2-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 function | Primary: 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, NO2 | Indoor 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 endotoxin | Bedroom 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 log | Hourly Time-Activity Diary: Diary of activities performed in the home during the sampling periods, including child sleep time, cooking and cleaning activities |
Household conditions | House Audit: Noise, light, shades, bedroom configuration base on interview and visual inspection66 |
Secondhand smoke | Urinary Cotinine: ELISA (Abnova, Walnut, CA; sensitivity 1 ng/mL) and questionnaire |
Neighbourhood physical environment (secondary exposures) | |
Neighbourhood walkability, poverty, disorder, social cohesion, crime | Neighbourhood 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 |
Rhinitis | ISAAC rhinitis core questions69 72 73 |
Respiratory illnesses | SICAS healthcare utilisation and respiratory infections (last 12 months)74 |
Adiposity | Exam: height, weight (BMI percentiles) |
General health | SICAS Medical History and Medications Questionnaire46 PROMIS Global Health 775 76 PROMIS Profile 2577 Patient Health Questionnaire-4 (PHQ-4)64 |
Demographics | Parent-reported questionnaire |
BMI, body mass index; FEF, forced expiratory flow; FEV1, forced expiratory volume in one second; FVC, forced vital capacity.