Introduction Early childhood wheeze has been classified according to triggers; exclusive viral wheeze (EVW) and multiple trigger wheeze (MTW). It has been proposed that these phenotypes differ in their aetiology, severity and prognosis.
Objectives To examine the prevalence and symptom severity of EVW and MTW in 2–6 year olds. To evaluate the stability of these phenotypes over time, and their association with later wheeze.
Method In two longitudinal birth cohorts comprising 18,362 individuals, data on respiratory symptoms were collected at age 2, 4 and 6 years. Parent-reported triggers were used to classify wheeze as EVW or MTW for each 2-year period. Logistic regression analysis was used to estimate odds ratios for current wheeze and relative risk ratios for wheeze phenotypes versus no wheeze, at follow-up compared with baseline.
Results At 2 years 17.6% and 22.6% (cohorts 1 and 2 respectively) had wheeze, of which 55.2% and 56.3% had MTW. At 6 years 69.7% and 75.7% of children with wheeze had MTW.
Among children with wheeze at baseline, 58–76% with EVW and 46–67% with MTW were in remission 2 years later (cohort 1) and 14–20% and 4–11% (cohort 2).
MTW had greater reported symptom-severity at all time-points compared with EVW.
When adjusted for symptom-severity, children with EVW at baseline had relative risk ratios (RRR) of 2.9–7.4 and 4.1–15.5 (cohorts 1 and 2 respectively) for EVW and RRR 1.7–2.9 and 1.6–4.0 for MTW at follow-up. Children with MTW at baseline had RRR of 3.1–6.2 in cohort 1 and 3.6–15.6 in cohort 2 for MTW and 1.1–2.7 and 1.4–7.0 respectively for EVW at follow-up.
Conclusions When adjusted for symptom severity, wheezing phenotypes based on reported triggers remained stable between 2–6 years of age. Symptom-severity may be a more important determinant than triggers of future wheeze classification in young children.
Statistics from Altmetric.com
If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.