A novel proportional index to differentiate between demographically and clinically matched cases with papillary thyroid carcinoma or non-cancerous nodule: PLR-to-PDW ratio.

objectivesTo analyze PLR-to-PDW ratio as a novel diagnostic index in the discrimination of benign thyroid nodules (BTN) and papillary thyroid carcinoma (PTC), and to analyze the discriminatory power of a novel index (platelet-to-lymphocyte ratio divided by platelet distribution width: PLR-to-PDW ratio) in comparison with previously-examined inflammatory indices including neutrophil-to-lymphocyte ratio (NLR), PLR, prognostic nutritional index (PNI), systemic inflammation index (SII), and systemic inflammatory response index (SIRI).

methodsThis cross-sectional retrospective research included 459 demographically and clinically-matched participants who underwent thyroid examination with ultrasonography and fine-needle aspiration biopsy. NLR, PLR, SII, SIRI and PLR-to-PDW were calculated manually from complete blood count results. PNI was calculated as albumin (g/dL) + 5 × lymphocyte count.

resultsAmong the inflammatory indices, NLR, PLR and PLR-to-PDW ratio were significantly higher in patients with PTC compared to those with BTN. Logistic regression showed that NLR (OR: 1.414, P=0.0083), PLR (OR: 1.537, P=0.0065) and PLR-to-PDW (OR: 2.054, P=0.0016) were independently associated with a greater likelihood of PTC. Among the previously-examined indices, PLR had the best discriminatory performance with 73.4% sensitivity and 70.8% specificity for a > 149.6 cut-off (AUC: 0.786, P=0.0011). However, the novel ratio examined in this study, PLR-to-PDW, had better predictive value to distinguish PTC cases from BTN with 78.1% sensitivity and 73.7% specificity at a > 9.11 cut-off (AUC: 0.827, P=0.0001).

conclusionsThe presently proposed PLR-to-PDW ratio exhibited the highest diagnostic discriminatory power compared to other inflammatory indices, indicating a relatively better utility to distinguish cases with PTC from those with BTN.