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Degree of Diabetic Retinopathy Correlates with Cardiovascular Risk

Dec 12, 2020
 
Editor: Steve Freed, R.PH., CDE

Author: Aleksandra Kusic, PharmD Candidate, Florida A&M University, College of Pharmacy and Pharmaceutical Sciences

Study finds patients with a higher degree of retinopathy severity had worse cardiovascular outcomes. 

Diabetic retinopathy can occur in a patient with type 2 diabetes who experiences uncontrolled blood sugar levels for an extended period. Blood vessels found at the retina’s light-sensitive tissue become damaged, leading to blindness if progression is not controlled. Clinical studies on the onset and management of this condition in patients with diabetes have determined that there is a correlation between the degree of retinopathy and cardiovascular events. Although the number of participants in these studies has not been vast, they present data to show that there is a correlation of diabetic retinopathy to increased cardiovascular events such as myocardial infarction, cerebrovascular accidents, or in some cases, death. To further address this implication, Dr. Midjtahedi and colleagues performed a retrospective study that involved patients with diabetes who were enrolled in Kaiser Permanente health plans. Monitoring their medical records, the team was able to identify new incidents of cerebral vascular accidents, myocardial infractions, and all-cause mortality that had developed within five years of a retinal evaluation. According to Dr. Modjtahedi, the patients with a higher degree of retinopathy severity had worse outcomes. The study emphasizes the importance of determining the impact that retinopathy progression has on the increased risk of cardiovascular disease, and potentially slowing down the progression of diabetic retinopathy. This study also sheds light on the importance of having an ophthalmologist and primary physician work together to develop a patient care plan to decrease diabetic retinopathy progression and improve patient outcomes.  

Patients with a previous diagnosis of congestive heart failure, cerebrovascular accident, and myocardial incidences were excluded from the study. This study’s total patient population was 68,206, divided into three categories by the degree of diabetic retinopathy severity: mild, moderate, and severe. Risk factors such as age, gender, race, smoking status, hypertension history, body mass index, glitazone use, lipid profiles, and estimated glomerular rate were also analyzed. This study was aimed to determine if retinopathy severity was independently associated with developing cardiovascular risk after adjusting for risk factors such as HbA1C, hypertension, smoking, and other risks.   

Results showed a significant increase in cardiovascular events in diabetic retinopathy patients compared to patients with no retinopathy. Patients with a mild degree of diabetic retinopathy presented a hazard ratio of 1.40 (CI=1.26-1.55) for cerebrovascular accident, 1.30 (CI=1.13-1.47) for myocardial infractions, and 1.20 for death (CI=1.10-1.30). Patients with a moderate degree of retinopathy had an increased risk in a cerebrovascular accident with a hazard ratio of 1.76 (CI=1.45-2.13), 2.13 (CI=1.78-2.59) for myocardial infarction, 1.62 (CI= 1.38-1.89) for death. In the third category of patients with severe retinopathy, there was a higher risk for cerebral accidents with a hazard ratio of 2.34 (CI =1.64-3.29), 2.08 (1.39-3.12) for myocardial infarction, and 1.72 (CI=1.25-2.98) for death. This higher degree of retinopathy shows a statistically significant increase in the risk of morbidity and mortality compared to patients with no retinopathy. A multivariate cox proportional-hazards model was performed. Of the total patient population, 1,680 (2.5%) suffered myocardial infraction, 2,269 (3.3%) suffered a cerebrovascular accident, and 3,756 (5.5%) died over five years since retinopathy diagnosis. 

As determined by this data, diabetic retinopathy is linked to cardiovascular events in the future, and there needs to be a treatment plan to stop the disease progression. An underlining cardiovascular disease can cause microvascular narrowing of the retinal arterioles. Therefore, an ophthalmologist is needed to detect the signs early of retinopathy and recommend a cardiovascular examination to patients, to detect risk factors that can contribute to the progression of retinopathy. 

These findings suggest that the five-year risk of cerebrovascular accidents, myocardial infractions, or death are independently associated with the degree of diabetic retinopathy even after adjusting for other risk factors. Cardiovascular risk factors such as hypertension, metabolic syndrome, smoking, and uncontrolled lipids can contribute to the worsening of retinopathy due to their shared disease pathways by negatively impacting blood vessels. Patients with diabetes need to get a comprehensive dilated eye exam once a year because early diagnosis of diabetic retinopathy can slow down the progression. The patient needs to understand the severity of how uncontrolled blood glucose could not only lead to retinopathy and consequential blindness but also cardiovascular events. Early diagnosis is essential for diabetic retinopathy because slowing down the progression will lead to better outcomes and decreased cardiovascular events. 

Practice Pearls:  

  • There is increased mortality and morbidity due to increased CV risk in diabetic retinopathy patients compared to patients with no retinopathy. 
  • Risk of cerebrovascular disease, myocardial infarction, or death increases in patients with diabetic retinopathy.  
  • Early diagnosis of diabetic retinopathy can improve patients’ outcomes and decrease the risk of developing cardiovascular events. 

  

Modjtahedi, Bobeck, et al. “Severity of Diabetic Retinopathy as an Independent Risk Factor for Cerebral Vascular Accidents, Myocardial Infarctions, and All-Cause Mortality.” 2020, pp. 1–2. 

  

Aleksandra Kusic, PharmD Candidate, Florida A&M University, College of Pharmacy and Pharmaceutical Sciences