Evaluation of an Individualised Quality of Life Questionnaire for Use in People with Cancer, the Cancer Dependent Quality of Life ("CancerDQoL") Questionnaire
Davidson J1, Taylor M2, Gilbride CJ3, Romaine J3, Wolstenholme V4, Tipples K4, Powell M4, Harrison M4, Bradley C3
1Royal Holloway University of London, London, UK, 2Royal Holloway University of London, Egham, UK, 3Royal Holloway, University of London, Egham, UK, 4Barts Health NHS Trust, London, UK
OBJECTIVES: Instruments currently used to measure QoL in cancer populations are neither individualised nor consistently condition-specific and focus overly on health status and functioning. Improved cancer survival rates and increased interest in its impact on QoL means accurate measures are needed. The current paper sought to validate for UK populations, a Cancer-Dependent QoL (CancerDQoL) questionnaire, originally designed with English-speaking Zimbabwean patients with cancer. METHODS: Ten semi-structured interviews were conducted with people diagnosed with any type of cancer to adapt the CancerDQoL for UK use. Psychometric analyses were conducted on data from 159 people with cancer to: determine the factor structure of the CancerDQoL through Exploratory Factor Analysis (EFA); establish internal consistency reliability with Cronbach’s alpha; and evaluate discriminant and construct validity through comparison with other measures (EQ-5D-VAS, EORTC-QLQ-C30 and W-BQ16) and health comorbidities. Based on pre-existing –DQoL templates (© Bradley), the CancerDQoL includes 4 overview items and 23 cancer-specific domain items. Domain items are rated for impact of cancer and importance for QoL. RESULTS: Semi-structured interviews resulted in removal of one item and minor formatting and wording changes. The resulting CancerDQoL revision was used for the subsequent psychometric evaluation. A mean negative impact of cancer was found on all domains of life. EFA revealed a 22-item solution explaining 46.37% of the variance. Internal consistency was excellent (α=0.943) and robust to missing data. Assessment of construct and discriminant validity substantiated the CancerDQoL as a condition-specific measure of the impact of cancer on QoL. CONCLUSIONS: Support is provided for the validity and internal-consistency reliability of the CancerDQoL, the first individualised, cancer-specific QoL instrument. Test-retest reliability and responsiveness require future investigation. The CancerDQoL can provide an accurate assessment of the impact of cancer and cancer treatments: facilitating improved QoL and allowing for investigation of treatment cost-effectiveness, including comparisons across patient populations and treatments.
Conference/Value in Health Info
2020-11, ISPOR Europe 2020, Milan, Italy
Instrument Development, Validation, & Translation, Patient-reported Outcomes & Quality of Life Outcomes