Our goal was to review a broad range of intervention studies aimed at improving the lives of caregivers of persons with dementia. Compared with previous reviews of this literature, the studies included here were broader in scope and more representative of recently published work. Moreover, we attempted to broaden the discussion of outcomes by raising issues of clinical significance in caregiver intervention research. Work in this area must ultimately meet this standard if our goal is to improve the lives of caregivers in meaningful ways.
Overall, the data suggest that there is evidence of clinically significant outcomes in the caregiver intervention literature. Most studies met criteria for social validity; study participants consistently rated the interventions as beneficial, helpful, or valuable. Researchers and policymakers would likely agree that social validity is important but is probably not the most valued indicator of clinical significance.
Interventions show promise of achieving clinically significant outcomes in improving depressive symptoms, and, to a lesser degree, in reducing anxiety, anger, and hostility. Although our ability thus far to improve overall quality of life for caregivers appears to be limited, there is evidence that specific components of quality of life, such as caregiver burden, mood, and perceived stress, are responsive to interventions. Finally, some impressive and clinically meaningful effects have been demonstrated for delayed institutionalization of the care recipient.
These findings are consistent with a recent meta-analysis of the intervention literature (Sorensen et al., 2002
) that showed that caregiver interventions produce statistically significant improvement of .14 to .41 standard deviation units, on average, for outcomes such as depression, caregiver burden, subjective well-being, and caregiver satisfaction. Our analysis of the literature augments these findings by showing how these effect sizes may be viewed in a public health context. We demonstrated that, across several studies, researchers were able to achieve outcomes with strong implications for public health goals and objectives. Interventions that result, for example, in delayed institutionalization or in significant improvements for crippling depression represent just two effects that serve critical interests in both the personal and the public health domains. Such outcomes have potentially far-reaching consequences for promoting health and wellness for all those affected by chronic disablement.
Our review further shows that there is no single, easily implemented, and consistently effective method for achieving clinically significant effects across caregivers. Most intervention studies examined in this review reported some level of success, and as a group, they provided valuable insights about different methods for achieving caregiver impact. There exists strong consensus that all caregivers are likely to benefit from enhanced knowledge about the disease, the caregiving role, and resources available to caregivers. Once the informational needs have been met, caregivers might additionally benefit from training in general problem-solving skills, as well as from interventions that target managing care recipient behaviors or caregivers’ own emotional response to caregiving. Some studies have taught the caregiver rudimentary behavior management skills, including behavioral assessment techniques and methods for changing antecedents and consequences of disruptive behaviors. Recent intervention studies have also suggested that there may be important synergies achieved by simultaneously treating care recipients (e.g., giving medications or memory retraining) and caregivers, and by altering the social and physical environments via multicomponent interventions.
The existing literature also contains a rich array of methods for delivering interventions to caregivers. Among these are traditional approaches, such as individual and group therapy sessions, as well as newer technologies involving enhanced telephone systems, computers, and the World Wide Web. As sophisticated communication technologies become easier to use and more readily available, treatment delivery options will increase.
When compared with previous dementia caregiver intervention reviews, our conclusions are decidedly more positive (cf. Charlesworth, 2001
; Cooke et al., 2001
; Pusey & Richards, 2001
). However, our conclusions need to be qualified by a host of methodological problems that still characterize much of this literature. First, sample sizes are often too small to detect even large effects (cf. Cooke et al., 2001
). For example, of the 43 distinct studies included in this review, only 1 would have been able to detect as statistically significant a small effect size, 14 a medium effect size, and 13 a large effect size (α set at .05 with 80% power). For the remaining studies, the samples were too small to detect even a large effect. Second, randomized controlled clinical trial methods have been used infrequently and are often implemented incompletely. For example, only 1 study reported intention to treat analysis to assess treatment effectiveness (Mittelman, Ferris, Shulman, Steinberg, & Levin, 1996
), and only 6 studies clearly indicated that outcome assessors were masked with respect to treatment assignment. Third, interventions were typically not well described, and treatment implementation data were infrequently collected or reported (Burgio et al., 2001
). Finally, the proportion of studies reporting clinically significant outcomes for important public health indicators was relatively small. Nevertheless, this work is instructive and provides important insights for the future development of this research area.
Clearly, there is room for increased methodological rigor in caregiver intervention research, and we have available good models and clear standards for enhancing the quality of research in this area (e.g., randomized controlled clinical trials methodology). These standards are being increasingly met by studies reported in the literature, and we strongly support continued improvement along these lines.
We have already made a number of methodological recommendations for future research. This list should be expanded to include a number of conceptual enhancements, such as the development of a standardized taxonomy for characterizing and measuring multicomponent psychosocial interventions (cf. Czaja, Schulz, Lee, & Belle, 2002
). The application of a clearly articulated and useful taxonomy would enable us to better describe and compare interventions across studies as well as link intervention components to specific outcomes. Closer attention paid to the assumed links between an intervention and the proposed outcomes would also be useful. For example, we should not expect that interventions aimed at reducing caregiver anger or hostility will also delay institutionalization for the care recipient. Furthermore, and this speaks directly to the issue of clinical significance, we need to be more careful in our choice of study participants. If we target caregivers who are at or near the normal range of depressive symptomatology, we are unlikely to achieve meaningful improvements with an intervention designed to decrease depression. In other words, we should be sure that the study participants display the problems targeted by the intervention.
The broad range of outcomes reported in this review is indicative of both strengths and weaknesses in the caregiver intervention literature. On the one hand, these outcomes point to the multifaceted impact of caregiving and the diversity of intervention effects that can be achieved. On the other hand, this diversity of outcomes along with the diversity of interventions make it difficult to reach strong conclusions about what has been achieved in this literature. We recommend that a core set of outcomes be included in all intervention studies and that they represent each of the four categories of clinical significance identified here. In making this recommendation, we are not advocating that all studies need to be designed to achieve clinical significance in all domains, but rather that at least some aspects of all domains be measured. Furthermore, it would be useful to develop consensus-based recommendations regarding specific measures to be used within each category of clinical significance. Once specific measures have been identified, the next step would be to reach consensus on what constitutes a clinically meaningful effect size for a given measure, along with recommended statistical procedures for demonstrating those effects (cf. Kendall, Marrs-Garcia, Nath, & Shedrick, 1999
Finally, and perhaps most important, researchers should set as their goal the achievement of reliable and clinically significant outcomes, preferably in multiple domains. To the extent that we succeed in achieving this goal, we will not only solve a vexing social problem but also advance the field of social/behavioral intervention research.