Clinical relevance: Diabetic macular oedema (DME) is a significant cause of visual impairment and inflammation plays an important role in its pathophysiology.
Background: This study evaluates the diagnostic value of systemic immune-inflammation index (SII) in the occurrence of DME in patients with non-proliferative diabetic retinopathy.
Methods: In this prospective study, the SII was applied to 150 consecutive patients with non-proliferative diabetic retinopathy. The relationship between the SII and the occurrence of DME was examined. Patients with DME were also divided into two subgroups according to the presence of accompanying sub-retinal fluid. The SII value was calculated as follows: platelet count × (neutrophil/lymphocyte). The risk factors for DME were evaluated using multivariate logistic regression analysis. A receiver operating characteristic (ROC) curve analysis of SII for predicting DME was performed.
Results: Patients with DME had significantly higher levels of SII than those without DME (599.7 ± 279.2 and 464. 9 ± 172.2, respectively, p < 0.001). However, The SII values were similar between sub-retinal fluid subgroups. Multivariate regression analysis indicated that SII, together with duration of diabetes, was an independent factor for DME occurrence [Odds ratio (OR) = 1.005, 95% confidence interval = 1.001-1.009, p = 0.04, and OR = 1.146, 95% CI = 1.049-1.252, p = 0.003, respectively]. ROC curve analysis revealed that the best cut-off value of SII was 399 (area under the curve: 0.633; sensitivity: 70%; specificity: 60%).
Conclusion: An elevated SII value is strongly associated with the development of DME. The SII may be a diagnostic biomarker for identifying DME to improve the risk stratification and management of non-proliferative patients with diabetic retinopathy.
Keywords: Diabetic macular oedema; diabetic retinopathy; subretinal fluid; systemic immune-inflammation index.