Atopy is a risk factor for adult asthma in urban community of Southwestern Nigeria

RATIONALE: Factors affecting asthma course are not clearly elucidated in urban communities in developing countries. Furthermore, the interaction between factors such as atopy, environmental exposure, urbanization, and helminthic infections in modulating asthma have not been well investigated. OBJECTIVES: To determine factors, which affect asthma in adults being evaluated at urban tertiary health center of Southwestern part of Nigeria. MATERIALS AND METHODS: A random sample of 24 (12 males, 12 females) consecutive asthmatics seen in the Outpatient Pulmonary Clinic of University College Hospital of Ibadan and 27 (13 males, 14 females) age and gender-matched controls underwent evaluation, which included blood tests for eosinophils, serum IgE, allergy skin tests to eight common environmental allergens, and spirometry. The modified version of the questionnaire of the International study of Asthma and Allergies in Children (ISAAC) Phase III used by the same study group of researchers in Nigeria was used to assess the asthma symptoms. Wilcoxon sign-rank tests were used to compare eosinophil counts, percentage eosinophils, and allergic skin test between the two groups, while paired t test was used to compare spirometry variables. RESULTS: Asthmatics had significantly more positive skin reaction to house dust mite and mould than controls (P<0.05). Total serum IgE was also significantly higher in asthmatics than in controls (mean 210 vs 60 IU/mL; P=0.003). However, no significant differences were observed in total eosinophil counts. No significant difference in the degree of intestinal helminthes infection in the two groups, which means stool parasitism was similar. FEV(1) % was significantly lower in asthmatics (P=0.02) but FEV(1) was similar between the two groups (P=0.02). CONCLUSION: The elevated levels of IgE and positive skin reactions to some of the common environmental allergens suggests an important role of atopy in the expression of asthma in this developing country's urban setting. Intestinal parasites were seen in both, control and asthma subjects, but appear not to play any role in the course of asthma, so also is the blood group, genotype and G6PD status.