ObjectiveTo determine the minimal clinically important differences (MCIDs) for the breast cancer scale QLICP-BR (V2.0) among the Quality of Life Instruments system for cancer patients (QLICP), which consist of the general module of 32 items classifying into 4 domains and the specific module of 10 items.MethodsAccording to the scoring rule of QLICP-BR (V2.0), the scores of each domain and the overall scale were calculated. The MCIDs of this scale were established by anchor-based and distribution-based methods. The anchor method used the Q29 item in the EORTC QLQ-C30 scale as anchors and defined the treatment effectiveness of the anchor-based method using criteria A (one level improvement after treatment) and B (at least one level improvement after treatment), while methods of effect size (ES), standard error of measurement (SEM), and reliability change index (RCI) were used in distribution-based methods.ResultsUsing the anchor-based method, according to standard A, the MCIDs of the physical domain (PHD), psychological domain (PSD), social domain (SOD), common symptoms and side effect domain (SSD), core/general module (CGD), specific domain (SPD), and the total score (TOT) were 16.24, 11.37, 11.31, 12.07, 11.49, 10.69, and 11.23 respectively; according to standard B, the MCIDs of PHD, PSD, SOD, SSD, CGD, SPD, and TOT were 18.88, 15.14, 14.10, 14.50, 13.93, 12.17, and 14.23 respectively. In the distribution-based MCID study, when ES = 0.8, the MCID values of each domain and the total score of the scale were 9.14, 10.34, 8.34, 10.54, 6.79, 9.73, and 6.96 respectively. The MCIDs calculated when a SEM of 1.96 was used as the intermediary index were 8.38, 11.04, 8.67, 10.00, 7.44, 9.83, and 7.81. The MCIDs calculated when a RCI of 1.96 was used as the intermediary index were 11.84, 15.61, 12.27, 14.14, 10.52, 13.90, and 11.05. Additionally, the MCID value calculated by the two standards of the anchor method was similar to 0.8 ES, 1.96 SEM, and 1.96 RCI.ConclusionUsing the anchor-based method, 0.8ES, 1.96SEM, and 1.96RCI have a better effect on the minimal clinically important difference of breast cancer scale and were recommended to be the preferred methods for establishing MCID.

ObjectiveThe aim of this study was to develop and validate the breast cancer scale among the system of quality-of-life instruments for cancer patients (QLICP-BR V2.0).MethodsProgrammed decision procedures and theories on instrument development were applied to develop QLICP-BR V2.0. A total of 246 breast cancer inpatients were investigated using QLICP-BR V2.0 from hospital admission until discharge. The reliability, validity, and responsiveness of the QLICP-BR V2.0 scale were evaluated by using the classical test theory combined with the generalizability theory (GT), including correlation analysis, multi-trait scaling analysis, factor analyses, t-tests, and also multivariate generalizability theory analysis.ResultsThe test–retest reliability of the total scale is 0.79, the Cronbach coefficient is 0.85, and the intra-class correlations coefficient is 0.88. The item–domain correlation analysis showed that the correlation coefficient between items and their own domain is greater than that with other domains except of item GSO4. The exploratory factor analysis showed that three principal components are obtained in the specific module. The outcome of the factor analysis coincides substantially with our theoretical conception. The score difference of each domain of the scale and the total scale before and after treatment is statistically significant (P < 0.05), with the standardized response mean of the total scale being 0.61. According to GT, the generalization coefficient of the scores in the 5 domains is between 0.626 and 0.768, and the reliability index is between 0.557 and 0.695.ConclusionQLICP-BR V2.0 exhibited reasonable degrees of validity, reliability, and responsiveness according to classical test and the generalizability theory. The number of items in the scale is appropriate.