Microvascular disease, modifiable risk factor profiles and incident arrhythmias in type 2 diabetes.

BACKGROUND: To assess the roles of diabetic microvascular disease and modifiable risk factors and their combination in the development of arrhythmias. METHODS: We included participants with type 2 diabetes (T2D) who were free of arrhythmias during recruitment in the UK Biobank study. The associations of microvascular disease states (defined by the presence of retinopathy, peripheral neuropathy or chronic kidney disease), four modifiable arrhythmic risk factors (body mass index, smoking, systolic blood pressure and glycosylated haemoglobin) and their joint associations with incident arrhythmias were examined. RESULTS: Among the 25 632 participants with T2D, 1705 (20.1%) of the 8482 with microvascular disease and 2017 (11.8%) of the 17 150 without microvascular disease developed arrhythmias during a median follow-up of 12.3 years. Having any of the three microvascular diseases was associated with a 48% increase in the hazard of developing arrhythmias. Incorporating microvascular disease states into a model alongside 11 traditional risk factors significantly enhanced arrhythmia prediction. Furthermore, individuals with microvascular disease who had optimal levels of zero to one, two, three or four arrhythmic risk factors showed an HR of 2.05 (95% CI 1.85, 2.27), 1.67 (95% CI 1.53, 1.83), 1.35 (95% CI 1.22, 1.50) and 0.91 (95% CI 0.73, 1.13), respectively, compared with those without microvascular disease. CONCLUSIONS: Although microvascular disease, a non-traditional risk factor, was associated with incident arrhythmias in individuals with T2D, having optimal levels of risk factors may mitigate this risk.

The Association Between Exposure to Air Pollution and Dementia Incidence: The Modifying Effect of Smoking.

BACKGROUND: The influence of overall air pollution on dementia risk and the potential effect modification by other risk factors remain to be clarified. METHODS: We included 459 844 UK residents who were free of dementia and had data on the exposure to particulate matter (PM)2.5, PM2.5-10, PM10, NO2, and NOx during baseline recruitment. The combined exposure to various PMs and NOx was estimated by using an air pollution score. Hazard ratios (HRs) and 95% confidence intervals (CIs) for incident dementia were estimated by multivariable Cox models. RESULTS: During a median 11.7 years follow-up, 5 905 incident cases of all-cause dementia were identified. With the exception of PM2.5-10, all other air pollutants were separately associated with a higher risk of all-cause dementia (all p-trend < .001) with generally similar associations for dementia subtypes. An increasing air pollution score was associated with higher risks of all-cause as well as individual dementia outcomes, with adjusted HRs (95% CI) of 1.27 (1.18, 1.37) for all-cause dementia, 1.27 (1.14, 1.43) for Alzheimer's disease, and 1.35 (1.16, 1.57) for vascular dementia when comparing the highest with the lowest quartile of the score (all p-trend < .001). These associations of air pollution score with dementia and its subtypes were observed among never and former smokers but not among current smokers (all p-interaction < .030). CONCLUSION: Air pollution was associated with a higher risk of dementia among nonsmokers but not current smokers. Additional studies are required to confirm our findings and to explore the potential mechanisms underlying the possible effect modification by smoking status.