Validation of the QUAL-EC for assessing quality of life in patients with advanced cancer

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Abstract

Objective

Improving quality of life is the main goal of palliative cancer care. However, there is a lack of measures validated specifically for advanced cancer. The purpose of this study was to validate the Quality of Life at the End of Life (QUAL-E) measure in a sample of patients with advanced cancer.

Methods

Data were analysed for 464 patients with advanced cancer who were participating in a randomised controlled trial of early palliative care intervention versus routine care. Patients completed the 26-item QUAL-E, the Functional Assessment of Cancer Therapy (FACT-G) quality of life measure and measures of spiritual well-being, performance status, symptom burden, satisfaction with care and communication with health care providers. We conducted a confirmatory factor analysis on the QUAL-E to test for the hypothesised four-factor structure and examined construct validity by calculating correlations with relevant scales.

Results

A 17-item reduced version of the QUAL-E, the QUAL-E-Cancer (QUAL-EC) achieved an acceptable fit to a four-factor model. Both the full and reduced versions of the QUAL-E were internally reliable and showed good construct validity. Symptom Control was correlated with other measures of physical functioning; Relationship with Healthcare Provider was correlated with satisfaction with care and better physician and nurse communication; Preparation for End of Life was strongly associated with emotional well-being; and Life Completion was strongly associated with social and spiritual well-being.

Conclusions

Due to its good factor structure and sound psychometrics, we recommend the reduced QUAL-EC scale to assess quality of life in patients with advanced cancer.

Introduction

Improvement of quality of life is the central goal of palliative cancer care.1 However, quality of life is a challenging construct to measure and to improve in palliative care populations, given the decline in general function that occurs in the last months of life.2, 3 Several validated measures of quality of life exist that are specific for cancer4, 5 or for palliative care populations.6, 7 More recently, general cancer measures have been modified or extended to evaluate patients with advanced cancer.8, 9 However, the latter measures were not originally developed for palliative care populations and may be incomplete in their content8 or too long to be routinely feasible.9 In this study, we validate a palliative quality of life measure in a sample of patients with advanced cancer.

The Quality of Life at the End of Life (QUAL-E) measure was designed to assess quality of life in patient populations nearing the end of life10 and is unique in that its development was based on qualitative research concerning perceptions of a good death.11 Participants in this research included patients with cancer and other life-threatening diseases, as well as healthcare professionals and bereaved family members. The instrument was subsequently validated in a mixed sample of patients with advanced cancer, heart failure, chronic pulmonary obstruction and renal disease, although the sample size was not large enough to compare factor models across disease type.12 There were also unexpected challenges regarding the QUAL-E’s subscale correlations and convergent validity. Specifically, one of the subscales unexpectedly was negatively correlated with two others, and only modest correlations were observed between the QUAL-E and the Functional Assessment of Cancer Treatment (FACT) measure of quality of life,5 which was used in this mixed disease sample despite being a cancer-specific measure. Although a recent review of quality of life instruments identified the QUAL-E as one of the most promising measures for use in palliative care settings, more investigation was recommended into its psychometric properties.13

The purpose of the present paper was to clarify the psychometric properties of the QUAL-E in a sample of patients with advanced cancer and to validate the measure in this population of patients. Specifically, we hypothesised that: (1) the QUAL-E would possess a four-factor structure; (2) Symptom Impact or Control would be positively correlated with other indicators of physical well-being and functioning; (3) Relationship with Healthcare Provider would be positively correlated with satisfaction with care and good communication with physicians and nurses; and (4) Preparation for End of Life and Life Completion would be positively correlated with social, emotional and spiritual well-being.

Section snippets

Participants and Procedure

Approval for this study was granted by the University Health Network Research Ethics Board. The participants were patients with advanced cancer enrolled in an ongoing cluster randomised controlled trial of early palliative care intervention versus routine oncology care. Patients were recruited from 24 outpatient oncology clinics at Princess Margaret Hospital, Toronto, Canada, and were randomised either to immediate consultation and follow-up by a palliative care team or to conventional cancer

Results

Table 1 shows the descriptive statistics of the sample. Our initial CFA found an unsatisfactory fit for a four-factor model, CFI = 0.85, NNFI = 0.82 and RMSEA = 0.08. The modification indices revealed that the three most complex items were Items 23, 4 and 13. Item 23 (I feel at peace) was supposed to be an indicator of Life Completion but was overly associated with Symptom Control, Preparation for End of Life and Relationship with Healthcare Provider. Item 4 (How worried are you about this symptom

Discussion

In this study, we examined the psychometric properties of the QUAL-E measure of quality of life in a large sample of patients with advanced cancer and validated a reduced version of the scale, the QUAL-EC. Both the full and reduced versions of the QUAL-E were internally reliable and showed good construct validity. Symptom Control was correlated with other measures of physical functioning; Relationship with Healthcare Provider was correlated with satisfaction with care and better physician and

Conflict of interest statement

None declared.

Acknowledgements

We are grateful to the patients who participated in this study and to the clinical and research staff of the Oncology Palliative Care Clinic and medical oncology clinics. This study was supported by the Canadian Cancer Society (#020509; CZ) and by the Ontario Ministry of Health and Long Term Care. The views expressed do not necessarily reflect those of the funding agencies. The funding agencies had no role in the study design, data collection, analysis and interpretation, writing or decision to

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    This research was funded by the Canadian Cancer Society (CCS, Grant #020509; CZ) and by the Ontario Ministry of Health and Long Term Care.

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