Reasons for exclusion at stage 2 on the basis of full text articles
| Reason for exclusion at stage 2 | Number of articles (%) |
| Adverse experience inadequately measured (e.g. retrospectively) | 12 (24) |
| Does not follow a prospective/longitudinal design | 9 (18) |
| Report on the same cohort (e.g. at an earlier follow-up stage) | 6 (12) |
| Asthma status inadequately measured (e.g. only uses stress biomarkers) | 5 (10) |
| Participants are not asymptomatic at baseline | 7 (14) |
| Articles retained for systematic review | 10 (20) |
| Total | 49 (100) |