Association of Long-Term Air Pollution with Prevalence and Incidence of Distal Sensorimotor Polyneuropathy: KORA F4/FF4 Study

Abstract

Background: Air pollution contributes to type 2 diabetes and cardiovascular diseases, but its relevance for other complications of diabetes, in particular distal sensorimotor polyneuropathy (DSPN), is unclear. Recent studies have indicated that DSPN is also increasingly prevalent in obesity.

Objectives: We aimed to assess associations of air pollutants with prevalent and incident DSPN in a population-based study of older individuals with high rates of type 2 diabetes and obesity.

Methods: Cross-sectional analyses on prevalent DSPN were based on 1,075 individuals 62-81 years of age from the German Cooperative Health Research in the Region of Augsburg (KORA) F4 survey (2006-2008). Analyses on incident DSPN included 424 individuals without DSPN at baseline (KORA F4), of whom 188 had developed DSPN by the KORA FF4 survey (2013-2014). Associations of annual average air pollutant concentrations at participants' residences with prevalent and incident DSPN were estimated using Poisson regression models with a robust error variance adjusting for multiple confounders.

Results: Higher particle number concentrations (PNCs) were associated with higher prevalence [risk ratio (RR) per interquartile range (IQR) $\text{increase}=1.10$ (95% CI: 1.01, 1.20)] and incidence [1.11 (95% CI: 0.99, 1.24)] of DSPN. In subgroup analyses, particulate (PNC, ${\mathrm{PM}}_{10}$, ${\mathrm{PM}}_{\text{coarse}}$, ${\mathrm{PM}}_{2.5}$, and ${\mathrm{PM}}_{2.5\text{abs}}$) and gaseous (${\mathrm{NO}}_x$, ${\mathrm{NO}}_2$) pollutants were positively associated with prevalent DSPN in obese participants, whereas corresponding estimates for nonobese participants were close to the null [e.g., for an IQR increase in PNC, $\text{RR}=1.17$ (95% CI: 1.05, 1.31) vs. 1.06 (95% CI: 0.95, 1.19); $p_{\text{interaction}}=0.22$]. With the exception of ${\mathrm{PM}}_{2.5\text{abs}}$, corresponding associations with incident DSPN were positive in obese participants but null or inverse for nonobese participants, with $p_{\text{interaction}}\le 0.13$ [e.g., for PNC, $\text{RR}=1.28$ (95% CI: 1.08, 1.51) vs. 1.03 (95% CI: 0.90, 1.18); $p_{\text{interaction}}=0.03$].

Discussion: Both particulate and gaseous air pollutants were positively associated with prevalent and incident DSPN in obese individuals. Obesity and air pollution may have synergistic effects on the development of DSPN. https://doi.org/10.1289/EHP7311.