Xuxi Zhang

DISCUSSION Our study found multifactorial intervention with individualized target and communication between health professionals and patients was more effective than other interventions in the prevention and control of DR. Interventions with follow ‐ up of over 5 years had better effect on reduction of DR development, and interventions with follow ‐ up of 2 to 5 years and over 5 years had better effect on reducing the risk of DR worsening. Our study showed that the effect of multifactorial intervention on reducing the risk of DR development was superior to that of blood ‐ pressure ‐ control intervention, glycemic ‐ control intervention or dietary ‐ control intervention. A previous study on multifactorial intervention among patients with type 2 diabetes also found that “intensive intervention with multiple drug combinations and behavior modification had sustained beneficial effects with respect to vascular complications and on rates of death from any cause and from cardiovascular causes”. 26 Apart from controlling multiple factors, we also found that the similarities of the multifactorial interventions on prevention of DR in the subgroup analysis were individualization and communication. Interventions and support for patients with type 2 diabetes were provided based on patients’ situation. 11, 13, 17 For example, patients could get recommendations on individualized goals to reach and could attend age and gender ‐ adjusted fitness programs. 13 Moreover, health professionals would communicate with patients through education sessions, phones and emails. 11, 13, 17 Additionally, we found dietary ‐ control intervention (Mediterranean diet supplemented with olive oil or nuts) are effective in preventing DR. A systematic review on dietary intake and diabetic retinopathy also found that Mediterranean diet, dietary fiber, fruits and vegetables, and oily ‐ fish have protective effect on DR. 27 However, both studies in our subgroup analysis of dietary ‐ control intervention are from the same article. The number of intervention studies exploring the effect of dietary intake on DR is very limited 20, 27 , thus more longitudinal studies in this field are needed. According to our pooled results, controlling blood pressure or blood glucose alone had no significant effect on preventing DR among patients with type 2 diabetes. The finding on blood glucose control is consistent with results from a previous meta ‐ analysis 1 on the effects of intensive glycemic control in ocular complications in patients with type 2 diabetes, which found no significant difference in the incidence of retinopathy. However, our finding on blood pressure is different from the result of a review of 15 RCTs on blood pressure stating that “the available evidence supports a beneficial effect of intervention to reduce blood pressure with respect to preventing diabetic retinopathy for up to 4 to 5 years”. 28 The possible reason of the differences might be that in our study blood pressure control alone would be regarded as blood ‐ pressure ‐ control intervention, while in that review article, blood pressure control alone and blood pressure control in combination with other interventions were all classified as blood ‐ pressure ‐ control intervention. In addition, we only included studies on patients with type 2 diabetes but the review included patients with both type 1 and type 2 diabetes. Regarding to the follow ‐ up intervals, our results showed that compared 174 Chapter 7