Determining the Minimal Clinically Important Difference of the Functional Assessment of Cancer Therapy Hepatobiliary Questionnaire to Evaluate the Change in the Quality of Life of Patients With Pancreatic Cancer During Radiation Therapy

This study aimed to define the minimal clinically important difference (MCID) for the FACT Hepatobiliary (FACT-Hep) questionnaire, allowing meaningful evaluation of the effect of radiotherapy (RT) on quality of life (QOL) in patients treated for pancreatic cancer (PC).The cohort included patients with PC who received RT as a component of curative intent therapy, who completed the FACT-Hep at baseline and end of treatment (EOT). The MCID was determined for the FACT-Hep and subdomains using anchor-based and distribution-based approaches. In the anchor-based approach, improvement and deterioration in age-adjusted regression models for change in scores were defined using the overall health assessment item of the PROMIS-10 as the anchor. The MCID was calculated as 0.3 and 0.5 standard deviation (SD) for distribution-based analysis. MCID point estimate using 0.5 SD (range) was averaged across time points and by approach, and the ranges are reported as minimum and maximum values across methods.The FACT-Hep domain with the lowest MCID was the emotional domain (deterioration 0.8-1.8). The hepatobiliary cancer subscale (HCS) has the highest and widest MCID range. A positive change of 2.9-4.3 in HCS should be considered a clinically relevant improvement. MCID estimates from 0.3 SD were in exact agreement with the anchor-based estimates for the physical domain (1.6-2.4). The MCID range for the Fact-Hep total score was 6.9-10.5 and 6.5-10.5 for improvement and deterioration, respectively.The MCID for the FACT-Hep subdomains and totals were calculated using a combination of anchor- and distribution-based approaches. These findings are fundamental to determine whether there is meaningful improvement or deterioration in QOL for patients with PC receiving RT. Evaluating a different anchor for determining the MCID of the social domain is recommended.