BACKGROUND Peripheral neuropathy is a common comorbidity in COPD. We aimed to investigate associations between alterations commonly found in COPD and peripheral neuropathy, with particular emphasize on the distinction between direct and indirect effects. METHODS We used visit 4 data of the COPD cohort COSYCONET, which included indicators of polyneuropathy (repeated tuning fork and monofilament testing), excluding patients with diabetes a/o increased HbA1c. These indicators were analysed for the association with COPD characteristics, including lung function, blood gases, 6-min walk distance (6-MWD), timed-up-and-go-test (TUG), exacerbation risk according to GOLD, C-reactive protein (CRP), and ankle-brachial index (ABI). Based on the results of conventional regression analyses adjusted for age, BMI, packyears and gender, we utilized structural equation modelling (SEM) to quantify the network of direct and indirect relationships between parameters. RESULTS 606 patients were eligible for analysis. The indices of polyneuropathy were highly correlated with each other and related to base excess (BE), ABI and TUG. ABI was linked to neuropathy and 6-MWD, exacerbations depended on FEV1, 6-MWD and CRP. The associations could be summarized into a SEM comprising polyneuropathy as a latent variable (PNP) with three measured indicator variables. Importantly, PNP was directly dependent on ABI and particularly on BE. When also including patients with diabetes and/or elevated values of HbA1c (n = 742) the SEM remained virtually the same. CONCLUSION We identified BE and ABI as major determinants of peripheral neuropathy in patients with COPD. All other associations, particularly those with lung function and physical capacity, were indirect. These findings underline the importance of alterations of the micromilieu in COPD, in particular the degree of metabolic compensation and vascular status.

中文翻译：

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COPD对多发性神经病的影响：德国COPD队列COSYCONET的结果。

背景技术周围神经病变是COPD的常见合并症。我们旨在研究COPD中常见的改变与周围神经病变之间的关联，特别强调直接作用和间接作用之间的区别。方法我们使用了COPD队列COSYCONET的第4次访问数据，其中包括多发性神经病指标（重复音叉和单丝测试），但糖尿病患者的HbA1c没有升高。分析这些指标与COPD特征的相关性，包括肺功能，血气，6分钟步行距离（6-MWD），定时测试（TUG），加重风险（根据GOLD，C-反应蛋白（CRP）和踝臂指数（ABI）。根据针对年龄，BMI，背包年和性别进行调整的常规回归分析结果，我们利用结构方程模型（SEM）来量化参数之间直接和间接关系的网络。结果606例患者符合分析条件。多发性神经病的指标彼此高度相关，并与碱基过量（BE），ABI和TUG相关。ABI与神经病和6-MWD有关，病情加重取决于FEV1、6-MWD和CRP。关联可以总结为包括多神经病作为潜变量（PNP）和三个测量指标变量的SEM。重要的是，PNP直接依赖于ABI，尤其是BE。当还包括患有糖尿病和/或HbA1c值升高的患者（n = 742）时，SEM几乎保持不变。结论我们确定BE和ABI是COPD患者周围神经病变的主要决定因素。所有其他协会，尤其是那些具有肺功能和体能的人是间接的。这些发现强调了COPD中微环境改变的重要性，特别是代谢补偿的程度和血管状态。