Development and validation of the general module of the system of quality of life instruments for cancer patients

Based on World Health Organization (WHO)'s definition of Quality of Life (QOL) and programmed decision procedures, we developed a general module of the System of Quality of Life Instruments for Cancer Patients (QLICP-GM) utilizing focus group discussions, pilot tests of 448 cases and field tests of 600 cases of 5 different cancer patients. The number of items in the final version was reduced to 32 from a 78-item pool. The psychometric properties of the scale were evaluated by indicators such as validity and reliability coefficients, SRM, and statistical methods of correlational analysis, t tests, and structural equation modeling. Correlational and structural equation model analyses indicate good construct validity with RMSEA 0.086, NNFI 0.947 and CFI 0.961. Good criterion-related validity was found when FACT-G was used as the criterion. The test-retest reliability for all domains and the overall scale is above 0.85; the internal consistency alpha for each domain is higher than 0.70 except of the social function; alpha and the split-half reliability of the overall scale is 0.88 and 0.93, respectively. The pre-post changes of QOL scores are of statistical significances in 3 domains of physical function, psychological function, common symptoms and side effects, and the overall instrument, with standardized response mean ranging from 0.16 to 0.67. Equivalence tests showed nonequivalence on quality of life score changes of these domains and the overall instrument. Our study shows that the QLICP-GM has good validity, reliability, responsiveness, and can be used as the general module for cancer patients in China.