Validation of the American version of the CareGiver Oncology Quality of Life (CarGOQoL) questionnaire
BACKGROUND
The CareGiver Oncology Quality of Life (CarGOQoL) questionnaire, a 29-item, multidimensional, self-administered questionnaire, was validated using a large French sample. We reported the linguistic validation process and the metric validity of the English version of CarGOQoL in the United- States.


METHODS
The translation process consisted of 3 consecutive steps: forward-backward translation, acceptability testing, and cognitive interviews. The psychometric testing was applied to caregivers of consecutive patients with representative cancers who were recruited from the Regional Cancer Center in northwestern Pennsylvania. All individuals completed the CarGOQoL at baseline, day- 30, and day- 90. Internal consistency, reliability, external validity, reproducibility, and sensitivity to change were tested.


RESULTS
The translated version was validated on a total of 87 American cancer caregivers. The dimensions of the CarGOQoL generally demonstrated a high internal consistency (Cronbach's alpha > 0.70 for all but four domain scores). External validity testing revealed that the CarGOQoL index score correlated significantly with all SF-36 dimension scores except the physical composite score (Pearson's correlation: 0.28-0.70). Reproducibility was satisfactory at day- 30 (intraclass correlation coefficient: 0.46-0.94) and day- 90 (0.43-0.92). Four specific dimensions of CarGOQoL showed responsiveness: the Psychological well-being, the Relationships with health care system, the Social support and the Finances.


CONCLUSIONS
The American version of the CarGOQoL constitutes a useful instrument to measure QoL in caregivers of cancer patients in the United- States.