The present meta-analysis examined the content of 29 randomized clinical trials addressing needs of family caregivers of cancer patients, and examined the efficacy of these interventions on different caregiver outcomes. The types of interventions delivered to caregivers in the 29 RCTs were psychoeducational, skills training, and/or therapeutic counseling. Many protocols were comprehensive in scope and addressed psychoeducational and skills training activities as primary or secondary goals. The majority of these interventions included content for caregivers that addressed caring for the patient, maintaining family and marital relationships, and caring for themselves, suggesting some consensus that these are essential content areas for interventions offered to caregivers. It should be noted, however, that many of the interventions were designed to address primarily patient care. Content about caregiver self-care was a secondary focus provided incidentally or as an afterthought in some patient-focused interventions. Fewer intervention protocols were designed with a goal of focusing on content related to caregivers’ self-care.
We observed two indicators of intervention quality in the studies reviewed. First, the majority (86%) included theory-driven intervention protocols, which decreased the likelihood of isolated or chance findings. There was considerable variability, however, as some studies mentioned the theory in passing or in generic terms (e.g., cognitive-behavioral approach), while others indicated specific theories (e.g., Lazarus or Bandura) and demonstrated how the theory was utilized in the identification of hypotheses, the selection of intervention content, and choice of outcomes. Second, most studies (75%) instituted ways to examine the fidelity of the interventions, i.e., the extent to which the designated protocol was delivered by intervention staff in a consistent manner. Investigators used protocol manuals, intervention logs, tape-recorded sessions, and/or independent reviewers to assess or maintain intervention fidelity, indicating a growing understanding of the importance of adherence to standardized protocols.
The majority of interventions were delivered jointly to patients and their family caregivers, suggesting that investigators recognize that both persons are affected by the illness. Only 9 of the 29 studies focused solely on caregivers by design, and those that did, generally utilized an individual face-to-face or telephone format. Only two studies conducted caregiver groups, an approach with potential value for caregivers to interact openly with other caregivers without the presence of the patient. There was considerable variability in the intervention “dose” among protocols, both in the number of sessions (Range = 2 to 12) and duration of interventions (Range = several days to 18 months). There also was variability regarding the proportion of the intended “dose” the caregiver could miss and still be considered an evaluable case. Mode of delivery and intervention dose appear to be areas that need further evaluation or standardization within studies; otherwise it is difficult to determine if, or how much of, the dose of the intervention or mode of delivery affects study outcomes.
One of the most important findings of this meta-analysis was that interventions delivered to family caregivers of cancer patients had a significant positive effect on multiple outcomes. The multiple caregiver outcomes exemplify the multifaceted impact of caregiving and point to the diversity of intervention effects that can be achieved. Caregivers reported better outcomes in the Illness Appraisal Domain (less caregiving burden, greater caregiving benefit, fewer information needs), Coping Resources Domain (use of more effective coping strategies, and higher self-efficacy), and Quality of Life Domain (better physical functioning, less distress and anxiety, better marital-family relationships, and improved social functioning). Intervention effects were evident soon after the intervention for many outcomes, but delayed for other outcomes such as caregiver benefit, physical functioning, and social functioning in longitudinal studies. These delayed effects may be due to the additional time required for caregivers to make the necessary changes or adjustments, and to see the improvements on these outcomes as a result of their efforts. Positive and sustained intervention effects were found for coping, self-efficacy, and distress/anxiety outcomes across studies and at initial, intermediate, and long-term assessments.
The small to medium effect sizes found for interventions in this meta-analysis were similar to the effect sizes found for outcomes in other meta-analyses either with family caregivers of patients with chronic illness,73–75
or with cancer patients themselves. For example, prior meta-analyses that examined the efficacy of psychosocial interventions found an overall moderate effect on cancer patients’ quality of life, 76,77
and on cancer patients’ anxiety.76,78,79
These findings are comparable to the small to moderate intervention effects we found on most quality of life outcomes for caregivers in the present meta-analysis.
Interventions were not effective in reducing caregiver depression. Explanations provided by individual investigators included low levels of baseline caregiver depression,63
and the high rate of attrition among depressed caregivers.61
A previous meta-analysis, using all types of cancer patients, reported that interventions were not effective in reducing cancer patients’ depression,78
a finding comparable to the present study. However, another meta-analysis reported a moderate-to-strong effect in trials assessing depression in breast cancer patients.76
These conflicting reports could potentially be attributed to the effects of gender and/or type of cancer. Finally, a prior meta-analysis indicates that interventions that improve coping in cancer patients appear to be more effective than those that aim to reduce depression in cancer patients.76
This finding is directly comparable to our findings for depression and for the positive and sustained outcomes we found in the coping resources domain.
There are a number of factors that may have contributed to the small to medium effects observed in the present meta-analysis. Many of the studies we analyzed had small sample sizes (e.g
., pilot studies) and high attrition rates, causing them either to be underpowered to detect intervention effects (Type 2 error) or to report inaccurate large effect sizes (publication bias).40
The only large intervention effect we found was for reducing caregivers’ need for information, and the significance of this finding is compromised by a significant Egger’s t
-test, which suggests a possible publication bias. However, the meta-analysis from Sorenson et al
also found large effects for improving caregivers’ ability/knowledge, which implies that this finding may not be accidental. Interestingly, even though the provision of information was provided in nearly all of the interventions analyzed in this meta-analysis, very few measured change in level of knowledge as a specific outcome. In addition, only 24% of the studies assessed intervention effects beyond six months post intervention, hindering the power to detect long term or delayed effects. Some studies were conducted with cancer patients and caregivers during a time when patients were doing well and caregiving demands were low, leaving little room for improvement in intervention outcomes.46
In some studies caregivers received fewer intervention sessions than patients (i.e
., 3 vs. 6 sessions) or a less targeted intervention than patients, decreasing the likelihood of detecting intervention effects.44,66
Finally, while interventions improved caregiver outcomes in some studies, they could not cure the patient’s disease or stop the disease from progressing, which therefore remained ongoing threats for the caregiver.
Moderator analyses yielded interesting results. Studies that addressed coping as an outcome had better results with a higher intervention dose (more intervention hours and more sessions). Coping behavior was enhanced either by promoting active coping, such as problem solving, or by reducing ineffective coping, such as avoidance and denial. Thus, the finding that higher intervention dose yielded better outcomes makes intuitive sense; changing a problematic coping behavior or enhancing a good coping strategy requires engagement with the task and changes take time to occur. Interventions delivered in face-to-face or in group meetings yielded better coping outcomes than those employing a mixed method of intervention delivery. One possible explanation for this finding is that in some studies that employed a mixed method of intervention delivery (F-F and Phone), the face-to-face meetings were focused primarily on patients’ needs with the caregiver in attendance, while the phone calls were focused entirely on the caregiver alone. It is possible that this approach did not allow the patient and the caregiver to work together as a team and enhance a common coping strategy. In any case, when using a mixed mode-of-delivery, it is difficult to separate the results attributable to the phone portion of the intervention from the face-to-face portion as these two approaches are nested in one set of results.
Interventions that included only caregivers resulted in more positive appraisal of caregiving benefit. These interventions were better able to focus on caregivers’ own needs and gave them the opportunity to better reflect on the meaning and the importance of, as well as their confidence in, their caregiving role. The finding that interventions addressing caregiving burden, depression, and marital-family relationships yielded worse outcomes with higher number of sessions is more difficult to interpret. Perhaps caregivers experiencing more burden or more marital-family conflict have difficulty participating in longer interventions because they take time away from their caregiving tasks or family responsibilities and unintentionally add to their caregiver stress. It is also possible that more depressed caregivers are more likely to drop out of longer interventions lessening the effect of the intervention on caregiver outcomes. Clearly, more research is needed to fully examine the relationship between intervention length and caregiver outcomes.
Limitations of the study
First, we did not include studies published in languages other than English, unpublished studies, dissertations, or abstracts from conference proceedings. On the one hand, including only published materials ensures that higher quality, peer-reviewed studies were included in the meta-analysis; on the other hand, excluding unpublished studies is likely to introduce an upward bias into the size of the effects found, which means that calculated effect sizes are likely to be larger.40
To address this limitation, we assessed heterogeneity of findings with the Q
statistic and publication bias with the Egger’s t
-test statistic. Publication bias appeared only in three outcomes, and may be related to a few studies with smaller sample sizes that assessed these outcomes. However, the effect sizes we reported are comparable to effect sizes of other meta-analyses assessing cancer patients’ outcomes. Second, given the large number of moderators and the multiple outcomes we tested, we had a high chance of incidental findings of statistically significant moderators. To account for this bias, we presented and interpreted moderators that were significant at 0.05 level for an overall outcome and not those that were significant for a subgroup within a particular outcome. Third, each of the moderators was examined in separate analyses. We did not assess multiple moderators in one meta-regression model due to the small/moderate number of studies for each outcome. Finally, we limited our choice of moderators to characteristics of the interventions rather than characteristics of the caregivers (i.e., age, gender, education, etc).
Clinical Application of Findings
There are several implications from this meta-analysis for clinicians and other health professionals working with cancer patients and their family caregivers. First, clinicians need to recognize that patients and their family caregivers react to cancer as a unit, and as a result, they both have legitimate needs for help from health professionals. There is general consensus in the literature that when patients and caregivers are treated simultaneously important synergies are achieved that contribute to the well-being of each person.9,80
When caregivers’ needs are not addressed, their mental and physical health is at risk, and patients are denied the opportunity to obtain optimal care from a well-prepared family caregiver. Programs of care directed only to patients are seldom sufficient to meet patients’ needs because so much of the patient’s care depends on family caregivers. In order to provide optimal comprehensive cancer care, the care plan must focus on these patient-caregiver units.
Second, there is clear evidence from this meta-analysis that interventions provided to caregivers of cancer patients can have many positive effects on important caregiver outcomes. Even though effects were small to moderate in size, interventions show promise of achieving clinically significant outcomes. Although interventions did not improve caregivers’ overall quality of life, there is evidence that specific components of quality of life were responsive to these interventions. Interventions significantly reduced caregivers’ burden, improved their ability to cope, increased their confidence as caregivers, reduced their anxiety, and improved marital and family relationships. These interventions produce more prepared, less distressed caregivers which, in turn, is likely to result in more positive benefits for patients. Our findings are consistent with reports of interventions targeting caregivers of chronically ill patients with dementia. Caregivers of dementia patients benefited from enhanced knowledge about the disease, the caregiving role, and available resources.80
Once their information needs were met, they benefited from additional training in general problem-solving skills.80
Third, there are several theory-based, comprehensive interventions that have been developed and tested in randomized trials. To our knowledge, few, if any, of these interventions have been translated for or implemented in clinical practice settings. Both researchers and clinicians need to work together to determine ways to implement efficacious evidence-based interventions in oncology treatment sites where caregivers can benefit from them. Most of these evidence-based interventions will not move from efficacy studies (Phase III) to effectiveness studies (Phase IV) unless researchers, clinicians, and funding agencies collaborate to facilitate the implementation of these studies in practice settings.
Directions for Future Research
Based on the findings from this meta-analysis, we have identified several areas in need of further research.
- Future studies need to have more racial, cultural, and socioeconomic diversity. In this meta-analysis, 16% of the participants were self-identified as members of a minority group and only two studies were tailored for a particular cultural or racial group.49,68
- More studies need to examine caregivers’ self-care behaviors and the physical health outcomes that follow. Caregivers often place patients’ needs above their own needs and as a result spend less time on health promotion activities for themselves such as exercise or cancer screening. Over time this could have negative consequences on caregivers’ health.
- There is a need for more research studies that identify patients and caregivers who are at higher risk for poorer outcomes, so that interventions can be targeted to them. While all caregivers should be provided with basic caregiving information as part of a comprehensive cancer care program, every effort should be made to identify those families at greater risk that are more likely to benefit the most from additional interventions.
- There is a need for large, well-funded, multisite studies to obtain larger samples of patients and caregivers in a reasonable amount of time, with long-term post intervention follow-up, and with a greater ability to generalize findings. Conducting intervention studies with cancer patients and their family caregivers is challenging and requires the support of clinicians, who can inform potential participants about available studies and encourage them to participate in them. These studies also need to be integrated into clinical care to determine how effectively they can be implemented in practice settings.
- Studies are also needed that assess intervention costs and their possible effect on health care resources. Of the 29 studies we examined, none of them addressed cost issues. More research is needed on how efficacious interventions can be delivered in a cost-effective manner.
- There is a need for studies that assess the potential for using technology to deliver effective interventions to caregivers. In our search of the literature for this meta-analysis, we found no published studies using the Web with our target population. This may be an important mode of intervention delivery to consider for future studies.
- There is a need to consider the clinical significance of interventions targeting caregivers of cancer patients in addition to their statistical significance. One major step in accomplishing this goal is to increase their methodological rigor, by being equally assured that studies are neither underpowered nor overpowered. A second step is to obtain consensus among health professionals from multiple disciplines on a set of core outcomes that are important to include and measure in all caregiver studies.80 Finally, consensus also is needed regarding the importance of the relationship between clinical and statistical significance, because even if effects are small, they may be important and associated with clinically meaningful outcomes.
In summary, findings from this meta-analysis indicate that interventions targeted to family caregivers of cancer patients can have a positive effect on many important caregiver outcomes. Researchers and clinicians need to work together to find ways to deliver research-tested interventions to patients and their caregivers so that both can cope effectively with the demands of cancer, and maintain their quality of life.