Urbanisation but not biomass fuel smoke exposure is associated with asthma prevalence in four resource-limited settings

Abstract

Background Urbanisation is an important contributor to the prevalence of asthma worldwide, and the burden of this effect in low-income and middle-income countries undergoing rapid industrialisation appears to be growing. We sought to characterise adult asthma prevalence across four geographically diverse settings in Peru and identify both individual and environmental risk factors associated with adult asthma. Methods We collected sociodemographics, clinical history and spirometry in adults aged ≥35 years. We defined asthma as meeting one of the three criteria: physician diagnosis, self-report of wheezing attack or use of asthma medications. We used multivariable logistic regression to assess individual and environmental factors associated with adult asthma. Results We analysed data from 2953 participants (mean age 55 years; 49% male). Overall asthma prevalence was 7.1%, which varied with urbanisation: highest in Lima (14.5%), followed by urban Puno (4.0%), semiurban Tumbes (3.8%) and rural Puno (1.8%). In multivariable analysis, being male (OR=0.60, 95% CI 0.39 to 0.93) and living at high altitude (OR=0.26, 95% CI 0.16 to 0.42) were associated with lower odds of having asthma, whereas living in an urban setting (OR=4.72, 95% CI 3.15 to 7.23) and family history of asthma (OR=1.83, 95% CI 1.19 to 2.73) were associated with higher odds. Current daily exposure to biomass fuel smoke (OR=1.18, 95% CI 0.70 to 1.91) and smoking (OR=0.99, 95% CI 0.73 to 1.22) were not associated with asthma. Conclusions These findings confirm that urbanisation is an environmental risk factor of asthma, questions biomass fuel smoke exposure as an important risk factor and proposes high altitude as possibly protective against the development of asthma.

Short-Term Fluctuations in Air Pollution and Asthma in Scania, Sweden. Is the Association Modified by Long-Term Concentrations?

“…Studies from Africa [5] and South America [6] have also reported similar findings. The main explanation for this difference is likely to be that the evolution of the Western lifestyle has resulted in relatively limited exposure to infectious agents during childhood [7], which expedite atopy by affecting the overall array of commensals and pathogens [8].…”

Environmental exposures and systemic hypertension are risk factors for decline in lung function

“…We found that household air pollution was associated with a higher prevalence of COPD and hypertension,16 17 that urbanisation was associated with a higher prevalence of asthma18 and that both household air pollution and urbanisation were associated with a higher prevalence of chronic bronchitis 19. In this longitudinal evaluation of the CRONICAS cohort study, we aimed to determine environmental and comorbid risk factors for accelerated lung function decline.…”

Cross-Sectional Comparison of Sleep-Disordered Breathing in Native Peruvian Highlanders and Lowlanders

“…Alternatively, daytime hypoxemia predicted sleep apnea in both Peruvian highland and lowland populations, suggesting that environmental exposures and/or concomitant cardiopulmonary dysfunction could also account for worsening of sleep apnea in our lowlanders. In fact, our lowlanders were more hypoxemic than expected, possibly due to the effects of urban air pollution and a high background prevalence of COPD and asthma in this district (Gaviola et al, 2016). Thus, the unusually high prevalence of hypoxemia in our lowland control population may have elevated the prevalence of SDB and attenuated the observed differences between our highland and lowland groups.…”