Life-course of atopy and allergy-related disease events in tropical sub-Saharan Africa: A birth cohort study.

Swaib A Lule,Moses Muwanga,Margaret Nampijja,Florence Akello,Harriet Mpairwe,Lawrence Muhangi,Alison M Elliott,Joseph Kahwa,Benigna Namara,Dennison Kizito,Gyaviira Nkurunungi,Emily L Webb,Stephen Nash,Joyce Kabagenyi

doi:10.1111/pai.12719

Abstract

BackgroundIn high‐income countries, allergy‐related diseases (ARDs) follow a typical sequence, the ‘Atopic March’. Little is known about the life‐course of ARDs in the markedly different, low‐income, tropical environment. We describe ARDs in a tropical, African birth cohort.MethodsUgandan children were followed from birth to 9 years. ISAAC questionnaires were completed at intervals; doctor‐diagnosed ARDs were recorded throughout follow‐up. Skin prick tests (SPTs) were performed at 3 and 9 years. Atopy was defined as ≥1 positive SPT.ResultsOf the 2345 live‐born children, 1214 (52%) were seen at 9 years. Wheeze and eczema were common in infancy, but by 9 years, only 4% reported recent wheeze, 5% eczema and 5% rhinitis. Between 3 and 9 years, atopy prevalence increased from 19% to 25%. Atopy at 3 or 9 years was associated with reported ARD events at 9 years, for example OR = 5.2 (95% CI 2.9–10.7) for atopy and recent wheeze at 9 years. Reported or doctor‐diagnosed ARD events in early childhood were associated with the same events in later childhood, for example OR = 4.4 (2.3–8.4) for the association between reported wheeze before 3 years with reported recent wheeze at 9 years, but progression from early eczema to later rhinitis or asthma was not observed.ConclusionAllergen sensitization started early in childhood and increased with age. Eczema and wheeze were common in infancy and declined with age. Atopy was strongly associated with ARD among the few affected children. The typical Atopic March did not occur. Environmental exposures during childhood may dissociate atopy and ARD.

Highlights

In high-income countries, allergy-related diseases (ARDs) follow a typical sequence, the ‘Atopic March’
Associations between atopy and reported ARD events at 9 years Skin prick test positivity was associated with all reported recent ARDs at 9 years (Table 2 (i)), with the strongest associations seen for wheeze and allergic rhinitis (PAF = 52.1% and 72.2%, respectively)
Eczema and wheeze were common in infancy, but prevalence declined markedly by 3 years, and there was no increase in later childhood

Summary

Introduction

In high-income countries, allergy-related diseases (ARDs) follow a typical sequence, the ‘Atopic March’. Phenotype, severity, inter-relationships and life-course of ARD events among children in this tropical birth cohort, to age 9 years. At ages 1, 2, 3, 5 and 9 years, caregivers were interviewed (in the child’s presence) on ARD symptoms using questions from the International Study on Allergy and Asthma in Children (ISAAC) questionnaire [15] and data on urticaria were collected.

Results

Conclusion