Platelet-to-Neutrophil Ratio Associated with Predicting DME

A recent cross-sectional study conducted in China has indicated the platelet-to-neutrophil ratio (PNR) can successfully serve as a diagnostic biomarker for diabetic macular edema (DME) in patients with diabetic retinopathy (DR).

PNR has recently become a widely utilized biomarker in a variety of fields; studies have shown it to be successful in predicting acute ischemic stroke, hemorrhagic transformation, and Grave’s orbitopathy.2,3

“PNR is a groundbreaking biomarker that amalgamates platelet count and neutrophil count, providing a more holistic reflection of the intensity of thrombotic and inflammatory processes, as well as their interplay,” wrote Huixin Sun, department of ophthalmology, the Second Affiliated Hospital of Chongqing Medical University, and colleagues. “However, PNR has been scarcely studied in the ophthalmic field.”1

The team enrolled 366 participants with type 2 diabetes mellitus (DM) aged ≥18 years, who were then categorized into the DR (n = 90), DME (n = 96), DM (n = 90), and healthy (n = 90) groups. DR and DME were diagnosed through clinical examination before being confirmed by optical coherence tomography (OCT) and fundus fluorescein angiography.1

The DME group was then also divided into 3 subgroups, based on the morphological patterns observed in the OCT: the diffuse retinal thickening (DRT) group (n = 21), the cystoid macular edema (CME) group (n = 44), and the severe retinal detachment (SRD) group (n = 31). The control group was made up of cataract surgery patients ≥18 years without underlying conditions.1

After diagnosis, each participant gave a venous blood sample. Sun and colleagues took complete blood cell counts of each sample, determining the neutrophil-to-lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR), and platelet-to-lymphocyte ratio (PLR).1

The team indicated that, after testing, neutrophil count was found to be significantly higher among the DME group compared to the healthy group (P =.006). Lymphocyte count was higher in the DM group compared to DME (P =.014), while platelet distribution width (PDW) was higher in the DM group compared to control (P =.030).1

Investigators then conducted a receiver operating characteristic (ROC) curve analysis to determine the best cutoff value of PNR to predict DME. The final threshold identified was a PNR of 68.51, with a sensitivity of 80.2% and a specificity of 75.6% (area under the curve [AUC]: 0.832, 95% CI: 0.773-0.891, P <.001). A PNR of ≤68.51 was then proven through binary logistic regression analysis to be significantly associated with DME prediction (odds ratio [OR]: 12.05, 95% CI: 5.93-24.47, P <.001).1

Once the DME group had been divided into CME, DRT, and SRD, duration of DM, lymphocyte count, MLR, and PLR were different across all 3 groups. Post hoc analysis indicated that the CME group had significantly higher duration of DM and lymphocyte count than the SRD group while MLR was substantially lower (P <.05). Duration of DM and PLR were significantly higher in the DRT group than SRD (P =.006 and P =.029 respectively), with no significant differences between CME and DRT. PNR remained comparable across all groups.1

With these results, Sun and colleagues have indicated that patients with DR that also have a lower PNR are more likely to develop DME. Additionally, further analysis revealed a threshold effect that states a PNR value of ≤68.51 has a robust association with DME development.1

“Consequently, PNR holds promise as a valuable diagnostic tool for detecting DME, offering potential improvements in risk stratification and management strategies for DR patients,” wrote Sun and colleagues. “However, further research is warranted to comprehensively explore the underlying relationship between PNR and the onset of DME, as well as to validate its clinical utility in broader populations.”1

References

1. Sun H, Li Y, Liu S, Pan C, Li D, Zhou X. The diagnostic value of platelet-to-neutrophil ratio in diabetic macular edema. BMC Ophthalmol. 2025;25(1):167. Published 2025 Apr 2. doi:10.1186/s12886-025-04001-2

2. Jin P, Li X, Chen J, et al. Platelet-to-neutrophil ratio is a prognostic marker for 90-days outcome in acute ischemic stroke. J Clin Neurosci. 2019;63:110-115. doi:10.1016/j.jocn.2019.01.028

3. Abounoori M, Pourazizi M, Bahmani Kashkouli M, Akha O, Jafari R, Movahedirad M. Novel immunoinflammatory blood markers in Graves' orbitopathy: insights into activity and severity. BMJ Open Ophthalmol. 2024;9(1):e001744. Published 2024 Dec 17. doi:10.1136/bmjophth-2024-001744