Unidad de Investigación Médica en Enfermedades Respiratorias, Hospital de Pediatría, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Mexico City, Mexico; Departamento de Investigación en Hiperreactividad Bronquial, Instituto Nacional de Enfermedades Respiratorias Ismael Cosío Villegas, Mexico City, Mexico.
Departamento de Alergia e Inmunología Clínica, Hospital de Especialidades, Centro Médico Nacional La Raza, Instituto Mexicano del Seguro Social, Mexico City, Mexico.
Respir Med. 2018 Feb;135:1-7. doi: 10.1016/j.rmed.2017.12.010. Epub 2017 Dec 19.
Previous studies suggest an inverse correlation between asthma and altitude. In the present work, we performed an in-depth analysis of asthma incidence in the 758 Mexican counties covered by the largest medical institution in the country (∼37.5 million insured subjects), and evaluated its relationships with altitude and other factors.
Asthma incidence in each county was calculated from new cases diagnosed by family physicians. Other variables in the same counties, including selected diseases, geographical variables, and socioeconomic factors, were also obtained and their association with asthma was evaluated through bivariate and multivariate analyses.
Median asthma incidence was 296.2 × 100,000 insured subjects, but tended to be higher in those counties located on or near the coast. When asthma incidence was plotted against altitude, a two-stage pattern was evident: asthma rates were relatively stable in counties located below an altitude of ∼1500 m, while these rates progressively decreased as altitude increased beyond this level (r = -0.51, p < .001). Multivariate analysis showed that, once each variable was adjusted by the potential influence of the others, asthma incidence was inversely correlated with altitude (standardized β coefficient, -0.577), helminthiasis (-0.173), pulmonary tuberculosis (-0.130), and latitude (-0.126), and was positively correlated with acute respiratory tract infection (0.382), pneumonia (0.289), type 2 diabetes (0.138), population (0.108), and pharyngotonsillitis (0.088), all with a p ≤ .001.
Our study showed that altitude higher than ∼1500 m comprises a major factor in determining asthma incidence, with the risk of new-onset asthma decreasing as altitude increases. Other less influential conditions were also identified.
先前的研究表明哮喘与海拔之间存在反比关系。在本研究中，我们对覆盖该国最大医疗机构的 758 个墨西哥县的哮喘发病率进行了深入分析，并评估了其与海拔和其他因素的关系。
通过家庭医生诊断的新病例计算每个县的哮喘发病率。还获得了同一县的其他变量，包括选定的疾病、地理变量和社会经济因素，并通过双变量和多变量分析评估了它们与哮喘的关系。
中位数哮喘发病率为 296.2×100,000 名参保者，但位于沿海或附近的县发病率较高。当哮喘发病率与海拔绘制时，出现了两阶段模式：海拔低于约 1500 m 的县的哮喘发病率相对稳定，而超过此水平时，这些发病率逐渐下降（r= -0.51，p <.001）。多变量分析表明，一旦每个变量都通过其他变量的潜在影响进行调整，哮喘发病率与海拔呈负相关（标准化β系数为-0.577），与寄生虫病（-0.173）、肺结核（-0.130）和纬度（-0.126）呈负相关，与急性呼吸道感染（0.382）、肺炎（0.289）、2 型糖尿病（0.138）、人口（0.108）和扁桃体咽炎（0.088）呈正相关，所有这些均具有统计学意义（p≤.001）。
我们的研究表明，海拔高于约 1500 m 是决定哮喘发病率的主要因素，随着海拔的升高，新发哮喘的风险降低。还确定了其他影响较小的条件。
