Epidemiology of asthma in two Peruvian cities: Differences in symptom reporting, spirometry, allergy skin testing, exhaled nitric oxide, and indoor air quality
Robinson, C; Baumann, L; Gilman, RH; Hansel, NN; Gonzalvez, G; Garcia, H; Cabrera, L; Wise, RA; Barnes, K; Breysse, P; Romero, K; Combe, JM; Gomez, A; Checkley, W
Rationale: According to a large-scale international study, Peru has the highest rates of asthma in Latin America and one of the highest worldwide. Data from this study, however, were limited to participants from very urbanized areas in Lima. By studying two Peruvian coastal cities of similar altitude but different degrees of urbanization, we aimed to provide a better understanding of the overall context of asthma in Peru in relation to environmental and genetic risk factors.
Objective: To determine differences in the epidemiology of asthma in two Peruvian cities via symptom reporting, spirometry before and after bronchodilators, allergy skin testing, exhaled nitric oxide (eNO), measurement of indoor particulate matter (PM) concentrations, and blood samples for future testing of genetic risk factors and IgE levels.
Methods: We randomly sampled from a community census and recruited 1444 adolescents aged 13 to 15 years from two cities, Lima (n=728) and Tumbes (n=716). All participants completed a questionnaire on symptoms, exposures, and sociodemographics and are currently undergoing the above clinical testing. To date, 960 children have undergone spirometry, allergy skin testing and eNO, and indoor PM has been measured in about 60 households.
Results: With few notable exceptions, the populations were relatively comparable in baseline exposures and sociodemographic characteristics. In contrast, in Lima versus Tumbes, wheezing in the last 12 months was 3-fold higher (10% vs. 3%, p<0.001), current asthma was 5-fold higher (10% vs. 3%, p<0.001), and lifetime asthma diagnosis was 6-fold higher (13% vs. 2%, p<0.001). Current rhinitis (23% vs. 13%, p<0.001), eczema (12% vs <1%, p<0.001) and smoking (7.8% vs. 1.3%, p<0.001) were also higher in Lima, whereas levels of atopy were comparable between the two cities (46% vs. 52%, p=0.24). The proportion of children with either obstruction or reversibility (FEV1/FVC < 70% or a 12% change in FEV1 from baseline) was also higher in Lima than in Tumbes (5.1% vs. 1.5%, p=0.05). The distribution of eNO values were skewed towards greater values in Lima than in Tumbes at the lower percentiles (Kolmogrov-Smirnov p<0.01). Finally, 48-hour mean indoor PM concentrations were much greater in Lima (42 vs. 24 µg/m^3, p<0.01).
Conclusions: Children in Lima had significantly higher prevalence of asthma symptoms, obstructive lung disease and reversibility, and higher levels of airway inflammation compared to Tumbes. This is consistent with a greater degree of urbanization, higher levels of indoor air pollution and greater levels of adolescent smoking but similar levels of atopy.
