Patient-Reported Outcome Measures of Long-Term Swallowing Function after Oropharyngeal Radiation Therapy: A Cross-Sectional Methods Comparison

Abstract

Definitive radiation therapy (RT) plays an important role in the curative treatment of many patients with oropharyngeal cancer (OPC), but carries a risk of long-term toxicity including the development of severe dysphagia. Here we characterize the relationship of patient-reported outcomes (PRO) of swallowing to quality of life (QOL) and radiation dose in long-term OPC survivors following definitive RT. Patients with non-metastatic OPC treated with definitive RT at a single institution between January 2000 and April 2014 were examined. All patients completed the MD Anderson Symptom Inventory—Head and Neck (MDASI-HN), the MD Anderson Dysphagia Inventory (MDADI), and the EuroQol five dimension questionnaire (EQ-5D VAS) 12 months or more following end of RT in a cross-sectional survivorship survey. A single dysphagia question from MDASI-HN (designated MDASI-HN-S) was used. An MDASI-HN-S score ≥6 and composite MDADI score <60 were considered representative of moderate-severe swallowing dysfunction. The Bayesian information criteria (BIC) were used to test the predictive power of MDASI-HN-S and composite MDADI with QOL as measured by EQ-5D VAS. The modified Breiman recursive partitioning analysis (RPA) was used to identify an MDASI-HN-S cut off score for poor QOL. To assess validity of PRO cutpoints, the mean dose to candidate regions of interest (ROI) were compared in patients with and without moderate/severe dysphagia symptoms. A total of 714 patients met criteria for inclusion, with 91.9% treated with intensity modulated radiotherapy (IMRT) and a mean time from treatment of 6.7 years. Moderate/severe dysphagia was reported by 17% and 16% of respondents by MDASI-HN-S and composite MDADI, respectively. QOL as measured by EQ-5D VAS was lower in those with moderate/severe dysphagia per both MDASI-HN-S (63.4 vs 83.5, p<0.001) and composite MDADI scores (64.5 vs 83.2, p< 0.001). Although both inventories were predictive of QOL, the model including MDASI-HN-S was slightly more parsimonious for discrimination of EQ-5D VAS scores compared to composite MDADI (BIC of 6062 vs 6076). Recursive partitioning analysis showed that an MDASI-HN-S cutoff score of ≥6 correlated best with EQ-5D VAS decline (LogWorth 2.7, p<0.001). Among 320 patients with available DICOM-RT plans, a higher mean dose to the contralateral anterior digastric muscle, intrinsic tongue muscles, and larynx was associated with moderate-severe dysphagia by both MDASI-HN-S and composite MDADI (all p <0.05). In long-term survivors of OPC following definitive RT, the single item dysphagia MDASI-HN-S question performed as well as the 20-item MDADI for discrimination of patient-reported dysphagia and QOL. Dose-response relationships to candidate ROIs were similar for the two questionnaires.