SPCS are a significant health-system investment. For 30 years, researchers have been working to define the improved outcomes associated with SPCS use [2, 12, 25, 30, 31, 45, 46, 48, 49, 61, 64]. The Health Omnibus data support that SPCS are associated with better meeting of needs for day-to-day hands-on caregivers while in the caregiving role and that SPCS have a subsequent long-term impact in improving a caregiver-defined outcome, moving on.
Finding the whole caregiver population (rather than only those referred to services) has been the dominant challenge in establishing caregiver benefits from SPCS involvement . By using a population-level method , this study avoided the bias introduced in studies which only access caregivers through clinicians, case note audits, or registries (clinical or death).
Impact of SPCS on caregivers while in the role
Our study builds on evidence that caregivers providing constant care who accessed SPCS had fewer unmet needs than did an otherwise identical population who did not access SPCS . Considering the five domains of the caregiving experience described by Given et al. , family support was the main domain identified as a source of unmet need; the proportion of respondents who identified unmet needs in this domain decreased when SPCS were involved. An additional category of unmet needs important to the caregivers in this study pertained to information needs and help with physical and medical aspects of caring. The largest proportion of identified unmet needs reported were in this category; fewer needs in this category were reported by caregivers of deceased individuals who had SPCS involvement.
Impact of SPCS on caregiver long-term outcomes
SPCS need proactively to minimize the health risks associated with caregiving . Other population approaches have shown associations of benefit with SPCS use in caregiver morbidity and mortality . Christakis and Iwashyna  analyzed 31,000 spousal survivors of someone who died from 1 of 13 frequent causes of expected death vs. propensity-matched to controls from the same US Medicare data set. Mortality rates for the surviving spouses were compared 18 months after the death. There was decreased mortality in the group who used SPCS for 24,721 female caregivers (5.4 vs 4.9%, OR 0.92, CI 0.84–0.99) and 6,117 male caregivers (13.7 vs 13.2%, OR 0.95, CI 0.84–1.06). The Omnibus study adds to the work of Christakis by suggesting not only that caregivers who interact with SPCS might have an association with less post-role mortality, but that they may adjust more rapidly to their new life after having been a caregiver.
Like Christakis’ work, this current study cannot attribute a cause-and-effect relationship, although it can demonstrate strength of association. Those willing to access services may have had a better outcome because of problem-focused coping strategies .
McCorkle et al.  conducted a randomized controlled trial (RCT) evaluating a home nursing intervention to support palliative caregivers. Despite initial improvement in psychological morbidity of bereaved caregivers in the intervention group, differences that were clinically and statistically significant at 6 and 13 months were no longer apparent by 25 months. Zisook and Shuchter  demonstrated that caregivers’ self-rated “adjustment” on a categorical scale showed progressive reductions in the first year. Such patterns are mirrored by our data.
In the McCorkle, Zisook, and Omnibus studies, there is a sizeable group of caregivers who still could not move on after several years. The fact that caregiver distress can last for so long after the death of the person for whom they have cared means that the measurement of service impact demands longitudinal approaches [32, 48, 60].
An RCT from Norway randomized access to SPCS by whole populations in a setting comparable to the current study . The primary outcome for “close family members” (whose level of caring was not clear) was the intensity of grief reactions as measured in the second part of the Texas Revised Inventory of Grief. There was no difference in grief reactions at 13 months in the 183 family members of the 434 patients who were originally enrolled in the study. By contrast, the higher level question, “Have you been able to ‘move on’?” in our study elicited a substantial difference over time between people who did and did not access SPCS. Although moving on constitutes only part of the definition for complicated grief  (or prolonged grief reaction), the measured rates of complicated grief in similar populations in the literature appear to be of the same order of magnitude, and at the same time after the death of the care recipient, as the findings from the Omnibus study [11, 39, 52].
Other predictors of caregiver outcomes
Our study supports other broad population-based observations that the intensity of the level of care provided directly correlates with longer-term caregiver outcomes including burden, health, and mortality [57, 59]. The level of caregiving helped to predict both unmet needs and the ability to move on.
One of the strongest predictors of an inability to move on was if the experience from diagnosis to death was “worse than expected;” this finding is consistent with other work in the area [8, 29]. The discrepancy between expectations and what actually happens can amplify feelings of lack of control over a situation. Conversely, a perceived sense of control is known to be related to overall wellbeing , and may contribute to an ability to move on.
Limitations to the study
Analysis was limited to the information collected by the South Australian Health Omnibus Survey, a retrospective population-based approach which is dependent upon recollections of bereaved respondents. Methodologically, a prospective study would have been preferable in order to establish potential causal relationships between SPCS and short- and long-term caregiver outcomes; however, it would not be practically feasible to conduct such a prospective controlled research study among caregivers at a population level.
Because the area of caregiving is a relative newcomer to the realm of clinical research, a paucity of robust assessment measures is, as yet, a major limitation of studies in this population. In assessment of short-term caregiver outcomes, we developed a variable to indicate level of intensity of caregiving, which we could link to caregiver strain. We could not encompass in this variable other factors not provided by the 2001–2003 Omnibus dataset, such as roles that caregivers might have been simultaneously performing.Thus, within our measure of caregiver strain defined by intensity of caregiving, we were unable to differentiate those caregivers who performed multiple roles from those who were solely caregivers.
With respect to long-term caregiver outcomes, as noted above, a validated instrument to measure moving on has not yet been developed; in the absence of such a measure, we acknowledge the respondent-defined nature of the concept as utilized in this study. As a first step toward defining this construct, we asked the 50 respondents for the 2003 annual Health Omnibus Survey pilot for input regarding what the concept of moving on meant to them. Results appear in Fig. 3 and provide some initial parameters for development of a measure of this construct.
People who live in remote South Australia and those without caregivers were not represented, and people from some cultural backgrounds may not be seen in these data. All results were based upon the recall of the respondent, which is a validated approach [35, 38, 62]. Caregiver-derived information about the uptake of SPCS is directly derived from first-hand knowledge. Other limitations of the approach have been outlined previously .
The programs offered through SPCS and their funding varies widely across the world, making global assessments of the impact of SPCS difficult [3, 15, 42]. This study reflects a variety of palliative care service types ranging from single-nurse-led rural services to large regional metropolitan interdisciplinary programs. These results can be generalized to similar health settings internationally.
The relationship between fewer unmet needs and SPCS suggests that SPCS do provide substantial support in helping to plan care and identify contingencies in future care. An understanding of the specific attributes of SPCS that make the most difference in meeting caregivers’ needs will be pursued through future work using similar methods.
Moving on was defined by respondents of a single year of the Health Omnibus Survey; broader validation is planned. Subsequent information will enable evaluation of whether moving on, as a measurable outcome, can be improved. An interesting line of inquiry, which would be made possible by inclusion of a baseline question in a future Health Omnibus Survey, is whether respondents who accessed SPCS were further along in the trajectory of psychological acceptance than were respondents who had not accessed SPCS. A positive correlation might indicate a self-selection bias in which respondents who had used SPCS and who had succeeded in moving on had a predisposition to move on, in comparison to respondents who had not chosen to access SPCS. While of academic interest, this information would not impact the utility of the finding that SPCS facilitated moving on among those individuals who accessed services.
The methodological strength of the approach used in this study, in which we probed data collected via the Health Omnibus Survey to answer a health services question on the population level, could be improved by favorable comparison of data from the Omnibus on caregiver assessment to data collected using a validated caregiver assessment instrument. This step represents a possible future avenue of study but is not yet possible due to the lack of such an instrument.
The relationship between caregivers’ expectations (diagnosis through death) and outcomes will be explored with two subsequent years of data. All results need to be confirmed in other health-delivery systems.