Diabetic retinopathy predicts all-cause mortality and cardiovascular events in both type 1 and 2 diabetes: meta-analysis of observational studies

Abstract

Objective: The prognostic significance of diabetic retinopathy (DR) for death and cardiovascular (CV) outcomes is debated. We investigated the association of DR with all-cause mortality and CV events in patients with diabetes by a systematic review and meta-analysis.

Research design and methods: The electronic databases Medline and Embase were searched for cohort studies that evaluated DR in type 2 or type 1 diabetic patients and reported total mortality and/or fatal and nonfatal CV events, including myocardial infarction, angina pectoris, coronary artery bypass graft, ischemic changes on a conventional 12-lead electrocardiogram, transient ischemic attack, nonfatal stroke, or lower leg amputation. Data extraction was performed by two reviewers independently. Pooled effect estimates were obtained by using random-effects meta-analysis.

Results: The analysis included 20 studies that fulfilled the inclusion criteria, providing data from 19,234 patients. In patients with type 2 diabetes (n = 14,896), the presence of any degree of DR increased the chance for all-cause mortality and/or CV events by 2.34 (95% CI 1.96-2.80) compared with patients without DR. In patients with type 1 diabetes (n = 4,438), the corresponding odds ratio was 4.10 (1.50-11.18). These associations remained after adjusting for traditional CV risk factors. DR was also predictive of all-cause mortality in type 2 diabetes (odds ratio 2.41 [1.87-3.10]) and type 1 diabetes (3.65 [1.05-12.66]).

Conclusions: The presence of DR was associated with an increased risk of all-cause mortality and CV events in both type 2 and type 1 diabetic patients.

Figure 1

Flow diagram shows the literature search to identify cohort studies that evaluated DR and all-cause mortality and/or CV events (fatal and nonfatal) of diabetic patients.

Figure 2

Meta-analyses of the association between presence of DR and (A) all-cause mortality and/or CV events (fatal and nonfatal) and (B) all-cause mortality in both type 2 and type 1 diabetic patients. (A high-quality color representation of this figure is available in the online issue.)

Figure 3

Bayes normogram for DR shows post-test probability of all-cause mortality and/or CV event in type 2 (A) and in type 1 (B) diabetic patients with DR (upper line) and without DR (lower line). C: Nomogram is shown for advanced DR in type 2 diabetic patients.