Minimal important difference of the 6-minute walk test after allogenic hematopoietic stem cell transplantation

Abstract

Purpose The 6-min walk test (6MWT) of allogenic hematopoietic stem cell transplantation (allo-HSCT) recipients has been gaining attention; however, minimal differences have not been reported. This study aimed to determine the minimal important difference (MID) in the 6MWT among hospitalized patients with allo-HSCT. Materials and methods The MID of the 6MWT was calculated using three different methodologies based on an anchor-based method; basic anchor-based methods, linear regression analysis, and receiver operating characteristic (ROC) curve analysis. The decrease in the score of Question 2 of the European Organization for Research and Treatment of Cancer Quality of life questionnaire core-30 was included as an anchor question for calculating the MID. Both actual and percentage changes in 6MWT values from baseline and at discharge were used in the MID calculations. In the actual and percentage change of the 6MWT, the one with the larger the area under the curve in the ROC curve was recommended as the MID. Results Among the three methods using actual values, the largest MID of the 6MWT was −37.5 m (sensitivity: 54%, specificity: 88%). Conclusion More careful follow-up after discharge is necessary for allo-HSCT patients who show a reduction of 37.5 m or more in the acute illness phase.