TABLE 1

Questionnaire items and definitions of wheeze phenotypes in the Avon Longitudinal Study of Parents and Children (ALSPAC) and the Leicester Respiratory Cohort Study (LRC)

ALSPACLRC
Current wheeze1) “Since your child was [age at previous questionnaire] old, has he/she had any periods when there was wheezing with whistling on his chest when he breathed?” (yes/no)
2) Has he/she had “wheezing” in the last 12 months? (yes/no)
Definition of current wheeze: positive response to 1) or 2)
1) “Has your child had wheezing or whistling in the chest in the last 12 months?” (yes/no)
Definition of current wheeze: positive response to 1)
Triggers of wheeze3) “What do you think brings on the wheezing attacks?”
 a) chest infection or bronchitis
 b) being in a smoky room
 c) cold weather
 d) I don't know
 e) other (please describe)
Responses to 2e) were coded into the following
categories:
  f) infections (upper or lower RTI)
  g) allergic triggers (airborne allergens, foods and
 beverages)
  h) physical activities or intense emotions
  i) damp or cold indoors or weather conditions
  j) air pollution
  k) asthma (diagnosed, suspected, family history)
  l) other (e.g. hot temperature, irritants, teething)
2) “In the last 12 months, has your child had wheezing or whistling in the chest during or soon after a cold or flu?” (yes/no)
3) “In the last 12 months, has your child had wheezing or whistling in the chest even without having a cold or flu?” (yes/no)
4) “In the last 12 months, did the following things cause wheezing in your child?”
 a) exercise (playing or running)
 b) laughing, crying or excitement
 c) contact with pets or other animals
 d) pollen (grass, hay, trees, flowers)#
 e) food or drinks
(answer categories for a–d: yes/no/don't know)

Phenotype definitionsEVW: 1 or 2 and 3a or 3f with no other categories reported
MTW: 1 or 2 and any of 3b, 3c, 3g–3j or 3l
NCW: 1 or 2 and no response to 3, or 3d or 3k with no other categories reported
EVW: 1 and 2 with no positive response to any of 3, 4a–4e
MTW: 1 and any of 3, 4a–4e
NCW: 1 and no positive response to any of 2, 3, 4a–4e

RTI: respiratory tract infection; EVW: episodic viral wheeze; MTW: multitrigger wheeze; NCW: non-classifiable wheeze.#: only asked from age 4 years onwards; : positive responses to listed questionnaire items required.