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In the last few decades, cancer care has shifted from the hospital inpatient setting to ambulatory settings. Combined with an ageing population and increased fiscal pressure on health care systems, this shift has resulted in families and other informal caregivers assuming increasing responsibility for patient care . Patients with advanced cancer often receive cancer treatment well into the palliative phase of their illness, with referrals to hospice or palliative care occurring late in the disease course [2-4]. The caregiving requirements are considerable for these seriously ill outpatients with cancer, who face complex medical problems as well as toxicities of treatment, without the support of a hospice team. However, few studies have examined the quality of life (QOL) of this group of caregivers . It is important to do so in order to evaluate whether and how these caregivers might benefit from early palliative care interventions.
Caregiver QOL is a multidimensional construct encompassing a broad range of elements including physical health, emotional well-being, social functioning, financial welfare and spirituality . It is related to, but distinct from caregiver burden , a construct originating in the geriatric literature, which has been defined as the perception of distress related to caregiving tasks . Caregiver QOL is by definition subjective and may vary between individuals based on differing personal values, perceptions and the stage of disease in patients for whom care is being provided .
A recent review of randomized trials for caregivers of cancer patients identified a need for research to determine patient and caregiver factors that could be targets for intervention . Further, a review of research on the QOL of caregivers of cancer survivors revealed few studies beyond the acute survivorship phase of diagnosis and treatment . Despite the heightened caregiving burden in the palliative phase of illness , studies of QOL at this stage are particularly sparse. Those that have been conducted were in mixed samples, comparing QOL in patients with advanced disease to those in acute phases of illness , or were small studies of patients who were already receiving hospice care [12-14]. To our knowledge, only one study has focused specifically on the QOL of caregivers of patients in the ‘late palliative phase’, which the authors described as ‘a condition beyond the curative phase, but [which] is not considered to be terminal’ ; these patients had metastatic cancer but a clinical prognosis of more than 4 months. This study, which was conducted in Norway, compared caregiver physical health and mental health (MH), measured by the Medical Outcomes Study Short Form (SF-36), with previously reported gender-specific norms. Physical QOL was higher than the norm in both genders, whereas MH was lower in male caregivers. This study did not, however, assess factors associated with QOL and MH in this population.
It has been theorized that variables associated with the caregiving experience and MH of caregivers of patients with cancer can be categorized into patient, caregiver and care-related factors . We have used this model to categorize possible factors associated with caregiver QOL. Potential patient-related factors include demographic and disease-related characteristics; caregiver-related factors include demographics, physical health and MH, other roles (occupational, family and social), living arrangements and the quality of the relationship with the patient; and care-related factors include the intensity and duration of care, help with caregiving and change in activities as a consequence of caregiving . Caregiver QOL has been found to be more strongly related to the MH than to the physical health of the caregiver [6, 16]. Therefore, in addition to examining the influence of MH on QOL, as has been done previously , we also examined factors that may specifically affect caregiver MH.
The purpose of the present study was to examine the QOL and MH of caregivers of ambulatory patients with advanced cancer and identify associations with patient, caregiver and care-related variables. We hypothesized that caregiver QOL would be related to caregiver characteristics, such as mental and physical health, female sex and younger age; to the QOL of the patient and to care-related characteristics, such as the amount of care provided and presence of and/or impact on roles other than that of caregiver. For caregiver MH, we had similar hypotheses but also that there would be an association with patient emotional well-being.
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To our knowledge, this study is the first to assess factors associated with the QOL and MH of caregivers of ambulatory patients with advanced cancer who are not yet receiving support from formal hospice or palliative care services. Caregivers were generally in good physical health, as indicated by the SF-36v2 physical component summary score of 52.5, which is higher than the US population norm of 50 and higher than that reported in caregivers in a home hospice setting (46.0). However, the score for the mental component summary was only 41.0. This is not only lower than the US norm of 50 but also lower than the values of 44.4 in men and 43.5 in women recorded in a Norwegian sample of caregivers of ambulatory patients with advanced cancer . It is also lower than the value of 44.0 found in a study of caregivers in a US home hospice setting , despite the fact that overall caregiver QOL in our sample was not as compromised as that of caregivers in that study (CQOLC score 99 vs 85). Thus, there appears to be considerable mental strain associated with caring for patients with advanced cancer who are still receiving hospital-based ambulatory care.
Despite the fact that the caregivers in this study were caring for patients with relatively good performance status, caregiver QOL correlated strongly with patient physical well-being. Similarly, caregiver MH was associated with patient emotional well-being. There are few studies that have compared QOL of caregivers to that of patients . A small study of 30 ovarian cancer patient–caregiver pairs showed a direct relationship between the QOL of women with cancer and the QOL of their caregivers , as did two studies in cancer survivors [11, 32]. Our findings are consistent with these studies, as well as with others showing that the QOL of family members is worse in those caring for patients with advanced disease [33, 34] and that there is an association between caregiver and patient depression scores . In contrast, a study in the hospice setting found no association of caregiver QOL with the patient's physical state . This may be due to the support provided by health care professionals in hospice care or due to the more uniformly poor patient QOL in this population.
There are few studies documenting the socio-economic hardship experienced by caregivers of patients with cancer. In the SUPPORT study, where family members of seriously ill patients hospitalized in the USA were interviewed post-discharge, a family member had to quit work or make another major life change to care for the patient in 20% of cases . In the current study, 25% of caregivers underwent a change in work situation (the majority working fewer hours, with a minority quitting their job, taking leave or losing employment) after becoming a caregiver for the patient. This is a substantial proportion, considering that close to half of the caregivers in our sample were retired, and the patients being cared for had a relatively good performance status, were receiving ambulatory cancer care and had a clinical prognosis of greater than 6 months. Changes in work situation and number of hours spent caregiving were independently associated with worse caregiver mental well-being. Although, to our knowledge, the association between changes in work situation and caregiver QOL has not previously been reported, studies in Turkey  and Norway  have found that being unemployed was associated with worse caregiver QOL. In another study, increased emotional distress was reported by caregivers with lifestyle interference and limitation in their ability to participate in valued activities and interests, regardless of how much care they were providing . It is difficult in all of these studies, including our own, to interpret the directionality of the association between reducing work or other activities and worse QOL. However, it is reasonable to conclude that one goal of interventions for caregivers of outpatients with advanced cancer should be to provide some relief from long caregiving hours and to enable continued engagement in meaningful activities or employment if this is desired.
Independent of female sex, QOL was also worse for caregivers who had other caregiving responsibilities in addition to those for the patient. These findings are similar to those of a study in cancer survivors , and emblematic of a demographic and cultural circumstance, in which caregivers, who are most often women, provide care for multiple dependents of different generations . Our finding that young age was strongly associated with poor QOL and MH on simple linear regression analysis, as in some other studies [11, 41], but not in multiple regression analyses, suggests that the distress of those who are younger could be related to the role strain of caring for multiple dependents  or to the strains associated with changes in work situation. In this vein, a previous study found that employed caregivers of cancer survivors, who were also taking care of children, reported greater levels of caregiver stress .
Consistent with other studies [6, 44, 45], caregivers' mental, but not physical health, was strongly associated with caregiver QOL. Female sex was associated with worse MH, consistent with other studies of cancer caregivers [34, 37, 46]. Possible explanations include that women might perceive themselves to have less choice in the assumption of a caregiving role or set higher standards for themselves as caregivers. In one study, male caregivers were more likely than female caregivers to judge the caregiving experience as boosting their self-esteem ; others have theorized that greater perceived negative aspects of caregiving are associated with decreased MH [47, 48]. There may also be differences in the caregiving tasks assumed: female caregivers tend to take on more personal care and time-consuming tasks than male caregivers [49, 50], and the latter may receive greater recognition for caregiving and less often have multiple dependents to care for.
Strengths of our study include that we assessed an understudied population, used a QOL measure specific for caregivers and included patient and care-related factors in our analysis. Limitations include that the patient and caregiver population was generally well educated, of relatively high income and of predominantly European ethnicity. Similar to other studies of cancer caregivers [6, 11, 38, 43], we included patients with a variety of different cancers. There might be patient-related factors that affect caregiver QOL, which are specific to caring for patients with particular cancer diagnoses, although tumour site group was not associated with caregiver QOL in this sample. The cross-sectional nature of the data allows only for the description of associations between variables and not for definite statements about causality. Although the percentage of variance in caregiver QOL related to variables in the multiple regression model was approximately 46%, it was lower at 19% for the MH model. Our study did not include contextual factors, such as quality of the caregiver–patient relationship and attachment style, which have been shown to influence caregiver MH in other studies [15, 51]. Longitudinal studies are needed in this population, as is research on other factors that may influence caregiver MH, and with caregivers of patients who have specific cancer diagnoses.
In summary, we have evaluated factors predicting caregiver QOL and MH among caregivers of outpatients with advanced cancer. Although such caregivers are caring for patients who are less ill than those in hospice populations and may provide fewer hours of actual hands-on care, they also have less access to hospice or palliative care services and are more likely to have other commitments in addition to their caregiving responsibilities. Our results indicate that these caregivers experience substantial distress, particularly related to their MH, and that interventions at this early palliative stage of illness are indicated for caregivers as well as patients. The relationships of caregiver QOL with patient physical well-being, and caregiver MH with patient emotional well-being, indicate that early palliative care interventions at the level of the patient might also benefit the caregiver. Also, the influence on caregiver QOL and MH of care-related factors, such as caring for other dependents, the amount of care provided and change in work situation, supports a role for interventions providing social assistance for caregivers, even at this relatively early stage of advanced cancer.
We extend our thanks to the staff of the medical oncology clinics for their facilitation of this research. This research was funded in part by the Canadian Cancer Society (grant nos. 017257 and 020509; C. Zimmermann) and by the Ontario Ministry of Health and Long Term Care. The views expressed do not necessarily reflect those of the funding agencies, which also had no role in the study design, data collection, analysis and interpretation, writing or decision to submit for publication. This study was previously presented in part at the American Society for Clinical Oncology Annual Meeting, 2011, Chicago, IL, USA, and at the Canadian Association for Psychosocial Oncology Conference, 2011, Toronto, Canada.