Abstract
Purpose:
To explore the relations between body mass index (BMI) and its variability and retinal vascular caliber.
Methods:
We used the data from a cohort study in Guangzhou, southern China. Subjects aged 40 years or older were recruited. BMI values were calculated annually between 2008 and 2012. Retinal vascular calibers were measured from digital retinal photographs taken in 2012. Subjects with at least 3 BMI measurements were included for statistical analysis. The average BMI (BMI mean) represented the BMI level of each subject during the check-up periods. Other variability indices in BMI could be divided into two distinct components, trend over time and fluctuation over time. Trend over time was calculated as the slope of BMI against the time of examinations (BMI slope), representing the direction and magnitude of weight change. Fluctuation over time was defined as the root mean square error around the regression line of BMI over the time (BMI RMSE) and the coefficient of variation of BMI (BMI CV), representing the magnitude of weight fluctuation. The associations of BMI and its variability with retinal vascular caliber were examined using linear regression models.
Results:
A total of 3494 subjects were available for analysis. In the multivariate regression model, higher BMI was significantly associated with both narrower retinal arteriolar and wider venular caliber (P=0.004 and 0.003, respectively). After controlling for potential confounding factors, greater BMI slope and greater BMI mean were significantly associated with retinal arteriolar narrowing (p=0.005 and 0.002, respectively). Measurements of BMI fluctuation were not found statistically associated with retinal vascular caliber (all P>0.05)
Conclusions:
Higher BMI was associated with narrower retinal arteriolar and wider venular caliber. Weight gain over time and long-term obesity status were associated with retinal arteriolar narrowing. The result suggests that long-term effects of weight gain on microcirculation may provide a novel pathophysiological basis to the epidemiological associations between weight gain and cardiovascular disease, and indicates the importance of avoiding weight gain and obesity from a novel perspective of microvasculature for the purpose of preventing cardiovascular disease.
Keywords: 465 clinical (human) or epidemiologic studies: systems/equipment/techniques