BACKGROUND AND OBJECTIVE Some children with asthma have low lung growth, putting them at increased risk for COPD later in life. However, it is currently not clear who will experience this adverse growth pattern. We therefore investigated the predictive role of blood eosinophils as a Type 2 inflammation marker in lung growth, focusing on the presence and severity of asthma. METHODS We investigated blood eosinophils and lung function growth (percentage predicted values) using linear mixed models in children and adolescents from two longitudinal cohorts. One cohort was hospital-based and consisted of asthmatic children at their first outpatient clinic visit after referral by the general practitioner (n=133, mean age 9.8) while the second was a general population-based birth cohort (PIAMA, asthma n=52 and non-asthma n=433, mean age 8.1). The hospital-based cohort had not been treated with inhaled corticosteroids (ICS) before referral. RESULTS Subjects in the hospital-based asthma cohort had more severe asthma compared to the asthmatic subjects in the population-based cohort, defined by lower lung function levels and a higher prevalence of bronchial hyperresponsiveness. In the asthma cohort, higher blood eosinophil numbers were associated with less growth in FEV1 (estimated change in lung function per 1 unit increase in ln blood eosinophils (B): -0.66 %/year (95% confidence interval (CI): -1.11 to -0.20, p<0.01) and FVC (B: -0.40 %/year (95%CI: -0.75 to -0.05), p=0.025) during follow-up in adolescence (min 7, max 17 years). These associations were not observed in the general population-based birth cohort, regardless of asthma status during follow-up (age 8-16). CONCLUSIONS & CLINICAL RELEVANCE Blood eosinophil counts in children with asthma not treated with ICS at referral were predictive of lower growth in FEV1 and FVC during follow-up in adolescence. Our findings indicate that this association is dependent on the degree of asthma severity. Future studies should address if anti-eosinophilic treatments preserve lung function growth in children with asthma.

中文翻译：

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血嗜酸性粒细胞与青少年哮喘患者肺功能生长降低有关

背景和目标 一些患有哮喘的儿童肺部发育缓慢，使他们在以后的生活中患 COPD 的风险增加。然而，目前尚不清楚谁将经历这种不利的增长模式。因此，我们研究了血嗜酸性粒细胞作为 2 型炎症标志物在肺生长中的预测作用，重点关注哮喘的存在和严重程度。方法 我们使用来自两个纵向队列的儿童和青少年的线性混合模型研究了血液嗜酸性粒细胞和肺功能生长（百分比预测值）。一个队列是基于医院的，由全科医生转诊后第一次门诊就诊的哮喘儿童组成（n = 133，平均年龄 9.8 岁），而第二个队列是基于一般人群的出生队列（PIAMA，哮喘 n = 52非哮喘患者 n=433，平均年龄 8.1）。以医院为基础的队列在转诊前未接受过吸入性皮质类固醇 (ICS) 治疗。结果 与基于人群的队列中的哮喘受试者相比，基于医院的哮喘队列中的受试者患有更严重的哮喘，其定义为肺功能水平较低和支气管高反应性的患病率较高。在哮喘队列中，较高的血嗜酸性粒细胞数量与 FEV1 的较少增长相关（估计 ln 血嗜酸性粒细胞增加 1 单位肺功能的变化 (B)：-0.66 %/年（95% 置信区间 (CI)：-1.11到 -0.20，p<0.01）和 FVC（B：-0.40 %/年（95%CI：-0.75 到 -0.05），p=0.025）在青春期随访期间（最短 7 年，最长 17 年）。这些无论随访期间（8-16 岁）的哮喘状态如何，在基于一般人群的出生队列中均未观察到相关性。临床相关性 在转诊时未接受 ICS 治疗的哮喘儿童的血液嗜酸性粒细胞计数可预测青春期随访期间 FEV1 和 FVC 的较低增长。我们的研究结果表明，这种关联取决于哮喘的严重程度。未来的研究应该解决抗嗜酸性粒细胞治疗是否能保护哮喘儿童的肺功能生长。