Assessment of pan-immune-inflammation value as a novel marker of proliferative diabetic retinopathy stage

To evaluate the predictive value of pan-immune-inflammation value (PIV) in the diagnosis of proliferative diabetic retinopathy (PDR) and its association with the stage of PDR.

This observational case-control study included participants who underwent routine complete blood count testing. Inflammation-related indices, including neutrophil-to-lymphocyte ratio, systemic immune-inflammation index (SII), and PIV, were derived and analyzed. Receiver operating characteristic curve (ROC) analysis was applied to assess the diagnostic performance of these indices in distinguishing patients with PDR, with sensitivity, specificity, area under ROC, and optimal threshold values calculated. In addition, binary logistic regression analysis was performed to evaluate the association between inflammatory indices and PDR stage.

This study included 205 patients: 60 with diabetes without retinopathy (mean age: 61.81±10.76y), 80 with PDR (mean age: 61.63±10.03y) and 65 healthy controls (mean age: 59.52±5.88y). The PDR group had significantly higher white blood cell (WBC, P<0.001), monocyte (MONO, P=0.009) and neutrophil (NEU) counts (P<0.001). SII and PIV had the highest sensitivity and area under ROC for predicting patients with PDR (0.822, 0.846, respectively). The optimal cut-off values for discriminating patients with PDR were determined to be >527.12 and >299.08 for SII and PIV, respectively. The logistic regression analysis demonstrated that a decrease in lymphocyte (LYM) count and an increase in platelet count (PLT), glycated haemoglobin (HbA1c), SII, and PIV were all significantly associated with the development of high-risk PDR (all P<0.05). PIV was more stable than independent MONO, LYM, PLT and NEU levels in predicting both the diagnosis and stage of PDR. The optimal cut-off value for PIV to discriminate patients with high-risk PDR was found to be >345.87 area under ROC=0.871, with sensitivity of 0.827 and specificity of 0.812.

PIV is a reliable, valuable, and inexpensive blood index that can be used for early detection and staging of PDR. PIV may therefore be essential to be used for the follow-up of diabetic patients.