The predictive usefulness of the novel "combined hemoglobin-to-platelet ratio and maximum mouth opening index" on prevalence of radiation induced trismus in patients with nasopharyngeal cancer.

Abstract

To explore how well a unique combination of hemoglobin-to-platelet ratio (HPR) and pretreatment maximum mouth opening (MMO) predicts the prevalence of radiation-induced trismus (RIT). HPR and MMO cutoff values (0.54 and 40.7 mm) divided patients into two groups. To develop the novel HPR-MMO index, four combinations of these factors were tested for predictive power: Group 1: HPR > 0.54 and MMO > 40.7 mm; Group 2: HPR ≤ 0.54 but MMO > 40.7 mm; Group 3: HPR > 0.54 but MMO ≤ 40.7 mm; Group 4: HPR ≤ 0.54 and MMO ≤ 40.7 mm. Data of 198 patients with LA-NPC was analyzed retrospectively. RIT rates for Groups 1 to 4 were 10.2%, 15.2%, 25%, and 59.4%. Groups 2 and 3 were merged to generate HPR-MMO index because of statistically equivalent RIT rates: Low-risk: HPR > 0.54 and MMO > 40.7 mm; Intermediate-risk: HPR ≤ 0.54 but MMO > 40.7 mm or; HPR > 0.54 but MMO ≤ 40.7 mm; High-risk: HPR ≤ 0.54 and MMO ≤ 40.7 mm. It was revealed that the low-, high-, and intermediate-risk group's RIT rates; 10.2%, 59.4%, and 19.2%, respectively. The novel HPR-MMO index may to classify LA-NPC patients into low, intermediate, and high-risk RIT groups.