Abstract 9708: Direct Normal Irradiance from Solar Radiation Negatively Correlates With Af Hospitalization in the United States

Abstract

Introduction: Medical radiation has been linked to increased risk of AF but any association between solar irradiation and AF remains unexplored. Aim: To study the role of solar radiation on AF. Methods: State-wise and county-wise CDC data with AF hospitalization rates in Medicare beneficiaries from 2015 to 2017 was used. Data regarding solar irradiation and other meteorological parameters, specifically, the midpoints of direct normal irradiation (DNI), direct horizontal irradiation (DHI), global horizontal irradiation (GHI), global tilted irradiation (GTI), terrain elevation, sunny hours, clear day and air temperature were collected from publicly available sources for 49 states. Bivariate and multivariable regression were carried out with environmental factors as the independent and AF as the dependent variables. Results: AF hospitalization correlated negatively with DNI [Standardized Beta Coefficient (β) = -0.352, p = 0.013], GHI (β = -0.146, p = 0.316), GTI (β = -0.264, p = 0.067) and terrain elevation (β = -0.590, p = 0.000), whereas DHI correlated positively with AF hospitalization rate (β = 0.480, p = 0.000). Other environmental factors such as sunny hours (β = -0.296, p = 0.046) and clear days (β = -0.198, p = 0.172) negatively correlated with AF hospitalization rates, but air temperature positively correlated with AF hospitalization rates (β = 0.374, p = 0.008). Multivariable regression analysis showed that DHI and DNI independently had a positive and negative correlation, respectively, to AF hospitalization rates after adjusting for potential confounders including age, COPD, hypertension, diabetes and air quality index. A sensitivity analysis with multivariate regression, adjusting for air temperature showed that DNI had a significant negative correlation (β = -0.277, p = 0.000) and DHI had a significant positive correlation (β = 0.370, p = 0.000) with AF hospitalization rates for the counties with five largest cities of each state. Conclusions: DNI (direct radiation without diffusion) negatively correlates with AF hospitalization rate, whereas DHI (rays scattering due to clouds, particulate matter and ozone) has a positive correlation. Further research may shed light on the mechanisms behind solar radiation-induced protection from AF.