Risk factors associated with rhinitis, allergic conjunctivitis and eczema among schoolchildren in Uganda.

BACKGROUND: The prevalence of allergy-related diseases (ARDs), including rhinitis, allergic conjunctivitis and eczema, is on the increase globally. The causes of this increase are not well established. OBJECTIVES: To investigate the risk factors associated with ARDs among schoolchildren in Uganda. METHODS: We conducted a secondary data analysis of a large asthma case-control study involving 1700 schoolchildren, 5-17 years, in urban Uganda. ARDs were defined according to the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire. Skin prick testing (SPT) was conducted using standard procedures and allergen-specific IgE (asIgE) using ImmunoCAP® . We employed inverse probability weighted analysis to generate estimated prevalence data and weighted odds ratios. RESULTS: The lifetime estimated weighted prevalence of reported rhinitis, allergic conjunctivitis and eczema was 43.3%, 39.5% and 13.5%; weighted prevalence in 12 months was 10.1%, 9.1% and 2.3%, respectively. There was overlap of ARDs, with 66.3% of 1193 schoolchildren who reported having ever an ARDs (including asthma) reporting two or more. Risk factors associated with reported rhinitis in the last 12 months were city residence at birth [adjusted odds ratio (95% confidence interval) 2.66 (1.42-4.99) compared to rural]; father's [2.62 (1.79-3.83)] and mother's history of allergic disease [2.12 (1.48-3.02)]; frequent de-worming in the last 12 months [2.01 (1.30-3.11), ≥2 versus none]; current high frequency of 'trucks passing on the street near home' [2.59 (1.48-4.52), 'almost all the time' versus rarely] and positive SPT [1.54 (1.09-2.18)] but not asIgE [1.38 (0.60-3.15)]. The same pattern of risk factors was observed for allergic conjunctivitis and eczema. CONCLUSION: We found extensive multi-morbidity of, and overlap in the risk factors for, rhinitis, conjunctivitis and eczema-similar to asthma risk factors-among schoolchildren in urban Uganda. This suggests a similar underlying cause for all ARDs, associated with exposure to urban lifestyles and environment in Uganda.