A Longitudinal Study on Development and Validation of the Prostate Cancer Scale Among the System of Quality of Life Instruments for Patients with Cancer (QLICP-PR V2.0) Based on Classical Test Theory and Generalizability Theory

BACKGROUND: The purpose of this study was to develop and validate the prostate cancer scale among the system of quality-of-life instruments for patients with cancer (QLICP-PR V2.0) to provide a reliable tool for assessing quality of life changes and clinical outcomes. PATIENTS AND METHODS: Application of programmed decision procedures, including multiple qualitative and quantitative analyses with general module and specific module combination pattern, were utilized to develop the QLICP-PR V2.0. On the basis of the data from 115 admitted and discharged patients with prostate cancer, the reliability, validity, and responsiveness of the QLICP-PR V2.0 scale were evaluated using correlation analysis, multi-trait scaling analysis, factor analysis, structural equation model, and paired t-tests, as well as combined with generalizability theory. RESULTS: Cronbach's alpha, test-retest reliability, and intra-class correlation coefficient of the total scale were 0.886, 0.896, and 0.889, respectively. Correlation analysis and factor analysis confirmed good construct validity and criterion-related validity. The score differences at all five domains and the total scale before and after the treatment were statistically significant (P < 0.05), with the SRM value ranging from - 1.152 to - 0.408, and the total scale was - 1.152. Generalizability theory results showed that the generalization coefficient of the five domains of the scale range from 0.575 to 0.764, and the reliability index between 0.529 and 0.748. CONCLUSIONS: The QLICP-PR V2.0 has good psychometric properties in reliability, validity, and responsiveness, and can be used to evaluate the quality of life of patients with prostate cancer.