Diabetic Retinopathy, Visual Impairment, and the Risk of Six-Year Death: A Cohort Study of a Rural Population in China
Authors: Cao Kai , Wang Bingsong , Friedman David S. , Hao Jie , Zhang Ye , Hu Ailian , Wang Ningli ,   The Handan Eye Study Group
Published: October 2020

<b><i>Purpose:</i></b> The aim of this study was to explore the association between diabetic retinopathy (DR) and the risk of 6-year death, as well as the association between visual impairment (VI) and the risk of 6-year death in a rural Chinese population of age ≥30 years. <b><i>Methods:</i></b> This was a population-based cohort study. In 2006–2007, 6,830 subjects aged ≥30 years were recruited from 13 villages in Northern China through clustered randomization. In 2012–2013, a 6-year follow-up was further done. Six different proportional hazards models, with different confounders adjusted, were used to explore the association between baseline DR and risk of death. <b><i>Results:</i></b> 5,570 subjects were included in this study by our inclusion and exclusion criteria. Four hundred and ten (7.36%) subjects died by follow-up. The median ages of the dead subjects and survived subjects were 67 (interquartile range [IQR]: 58–72) years and 52 (IQR: 42–58) years (<i>Z</i> = 21.979, <i>p</i> &#x3c; 0.001). Male accounted for 62.20 and 44.92% among the dead and survived subjects (χ<sup>2</sup> = 45.591, <i>p</i> &#x3c; 0.001). Besides, compared with those survived, the dead were found to be with lower education (χ<sup>2</sup> = 109.981, <i>p</i> &#x3c; 0.001), lower marriage rate (χ<sup>2</sup> = 101.341, <i>p</i> &#x3c; 0.001), lower income (χ<sup>2</sup> = 123.763, <i>p</i> &#x3c; 0.001), higher proportion of smoking (χ<sup>2</sup> = 8.869, <i>p</i> = 0.003), higher systolic blood pressure (<i>Z</i> = 10.411, <i>p</i> &#x3c; 0.001), lower body mass index (<i>Z</i> = −3.302, <i>p</i> = 0.001), larger spherical equivalent error (<i>Z</i> = 4.248, <i>p</i> &#x3c; 0.001), lower intraocular pressure (<i>Z</i> = −4.912, <i>p</i> &#x3c; 0.001), smaller anterior chamber depth (<i>Z</i> = −9.186, <i>p</i> &#x3c; 0.001), larger length thickness (<i>Z</i> = 11.069, <i>p</i> &#x3c; 0.001), higher fast blood glucose level (<i>Z</i> = 5.650, <i>p</i> &#x3c; 0.001), higher total cholesterols (<i>Z</i> = 2.015, <i>p</i> = 0.044), higher low-density lipoprotein (<i>Z</i> = 2.024, <i>p</i> = 0.043), and higher proportion of drug usage (χ<sup>2</sup> = 56.108, <i>p</i> &#x3c; 0.001). Besides, the dead subjects were more likely to be with VI, glaucoma, cataract, age-related macular degeneration, diabetes, and DR. Hundred and forty-eight subjects were diagnosed with DR at baseline, and 33 (22.30%) of them were dead before follow-up. By adjusting all relative confounders in a proportional hazards model, DR was found to be a risk factor of 6-year death, the hazard ratio was 1.739 (95% confidence intervals: 1.080, 2.803). Another 5 different statistical models with different confounders adjusted also revealed a statistically significant association between DR and 6-year death. The association between VI and 6-year death was not statistically significant. <b><i>Conclusions:</i></b> DR increased the risk of 6-year death in a rural Chinese population aged ≥30 years, while VI did not.