Background: The primary goal of palliative care is to optimize the quality of life (QOL) of people living with a life-threatening illness and that of their families. While there have been important advances in measurement of the QOL of palliative care patients, little attention has been paid to the QOL of their carers (family caregivers). To develop and deliver the most effective services to these carers, their QOL needs to be measured with acceptable and psychometrically sound instruments that have content validity.
Methods: This study reports three phases of the development and testing of such a measure: QOLLTI-F, Quality of Life in Life Threatening Illness--Family Carer Version, simultaneously in English and French. Participants were carers from 12 Canadian palliative care services who were asked to complete QOLLTI-F on three occasions.
Results: The final version of QOLLTI-F consists of 16 items. It was deemed acceptable by the vast majority of carers and a longer, 24-item version was completed in a median of 12 min. Content validity was assured by inclusion of all domains reported by carers to be important to their QOL: state of carer, patient wellbeing, quality of care, outlook, environment, finances and relationships. Construct validity was demonstrated, as principal components analysis indicated that the 16 items did indeed reflect these seven domains. Furthermore, the seven domain scores predicted 53% of the variance in global QOL, although the QOLLTI-F Total score predicted less well (43%). The test-retest reliability for the QOLLTI-F Total score was 0.77-0.80 and ranged from 0.50 to 0.79 for the seven domain scores. All QOLLTI-F scores were shown to be significantly different between days the carers considered bad, average and good, demonstrating responsiveness to change, with the exception of the Financial Concerns submeasure, which did not distinguish between average and good days.
Conclusions: QOLLTI-F is unique in that in measuring one person's QOL (the carer's) it includes their perception of the condition of another (the patient). This attests to the close relationship between the two. It is also unique in that its content is derived from a qualitative study asking carers what is important to their own QOL, rather than focusing on the changes or burdens related to caregiving. QOLLTI-F also has the advantage of being briefer than other carer QOL measures. It contains measures of seven different domains that are determinants of carer QOL, in addition to a summary score. All these measures are valid, reliable and responsive to change in QOL.