Temporal stability of multitrigger and episodic viral wheeze in early childhood.

The distinction between episodic viral wheeze (EVW) and multitrigger wheeze (MTW) is used to guide management of preschool wheeze. It has been questioned whether these phenotypes are stable over time. We examined the temporal stability of MTW and EVW in two large population-based cohorts.We classified children from the Avon Longitudinal Study of Parents and Children (n=10 970) and the Leicester Respiratory Cohorts ((LRCs), n=3263) into EVW, MTW and no wheeze at ages 2, 4 and 6 years based on parent-reported symptoms. Using multinomial regression, we estimated relative risk ratios for EVW and MTW at follow-up (no wheeze as reference category) with and without adjusting for wheeze severity.Although large proportions of children with EVW and MTW became asymptomatic, those that continued to wheeze showed a tendency to remain in the same phenotype: among children with MTW at 4 years in the LRCs, the adjusted relative risk ratio was 15.6 (95% CI 8.3-29.2) for MTW (stable phenotype) compared to 7.0 (95% CI 2.6-18.9) for EVW (phenotype switching) at 6 years. The tendency to persist was weaker for EVW and from 2-4 years. Results were similar across cohorts.This suggests that MTW, and to a lesser extent EVW, tend to persist regardless of wheeze severity.