Eczema Trajectories
“Eczema trajectories” are the different courses childhood eczema takes over time, found by following whole birth cohorts rather than clinic patients. Paternoster et al. (JACI 2018) applied latent class analysis to parent-reported rash in the UK ALSPAC cohort (9,894 children followed to 16.5 years) and the Dutch PIAMA cohort (3,652 children followed to 11). Both cohorts produced the same six patterns. This suggests Atopic Dermatitis in children is several overlapping conditions with different causes, not one disease with one natural history.
Eczema Trajectories [defines] Eczema Prognosis ALSPAC [supports] Eczema Trajectories PIAMA [supports] Eczema Trajectories
The six classes. About 58–63% of children were unaffected or had only transient rash. The commonest eczema pattern was early-onset-early-resolving (12.9–15.4%). Rash peaked at 18–30 months and fell to about 10% by age 6–7. It was more common in boys and only weakly linked to later Asthma. Early-onset-persistent eczema (4.9–7.3%) still had about half of children with rash at 16.5. Early-onset-late-resolving eczema (3.8–7.0%) faded only in adolescence. Mid-onset-resolving (~7%) peaked around age 6, and late-onset-resolving (~7–8%) rose again around age 12 and was more common in girls. The figures come from parent reports of rash, not doctor-confirmed diagnoses.
Eczema Trajectories [relates] Asthma
What separates the classes. Filaggrin (FLG) null mutations were most strongly tied to early-onset-persistent eczema (OR 4.31 in ALSPAC). The persistent classes also had the strongest links to a genetic risk score, parental atopy and asthma. The mid-onset class was strongly linked to asthma but not to FLG, which suggests a different pathway. The authors found that every eczema class carried some extra asthma risk, but the data “did not support the presence of a specific trajectory from AD to asthma”. Belgrave et al. (PLoS Med 2014; MAAS and ALSPAC, 9,801 children) reached a similar view: only about 7% of children with any allergic symptoms followed the classic Atopic March sequence. The German Multicenter Allergy Study (Illi 2004) added that atopic sensitisation was a major determinant of poor prognosis (aOR 2.76), and that early eczema without early wheeze or sensitisation carried no extra wheeze risk.
Filaggrin [causes] Eczema Trajectories Eczema Trajectories [contradicts] Atopic March Multicenter Allergy Study [supports] Eczema Trajectories
What it means for a 1–4-year-old. For most toddlers with eczema, the likeliest course is the early-resolving pattern, with rash improving by school entry. A toddler cannot yet be reliably placed into a class, because the classes are defined by what happens later. Pointers to a more persistent course are severe or widespread disease, a family history of atopy, a known FLG mutation or Ichthyosis Vulgaris, and early wheeze or food sensitisation (Eczema Prognosis). Studies disagree on whether onset before age 2 predicts a shorter or longer course (see the conflict noted in Eczema Prognosis). No trial has shown that any treatment moves a child from a persistent to a resolving trajectory. Good control still matters for sleep, comfort and infection risk in the meantime.
Ichthyosis Vulgaris [relates] Eczema Trajectories
Connections
- Eczema Prognosis — defines the range of outcomes, source: Paternoster 2018
- ALSPAC — source cohort, source: Paternoster 2018
- Filaggrin — FLG null mutations OR 4.31 for early-onset-persistent class, source: Paternoster 2018
- Asthma — strongest with persistent and mid-onset classes, source: Paternoster 2018
- PIAMA — Dutch replication cohort, source: Paternoster 2018
- Atopic March — only ~7% of symptomatic children follow a march-like path, source: Belgrave 2014
- Multicenter Allergy Study — sensitisation predicts persistence (aOR 2.76), source: Illi 2004