Included studies
Using electronic database searches we identified 6,556 records for title and abstract screening after removing duplicates (figure 1). We conducted a full text review of 263 records, of which 16 met all the inclusion criteria and were included in the narrative synthesis. Foreign language full text articles were translated (seven in Japanese, two in Spanish, two in German, two in Chinese (simplified) and one in French). No additional studies were found through grey literature searching, or hand searches of journal contents of included studies’ reference lists.
Initial rates of agreement between the two reviewers were 97% for screening, 98% for data extraction and 94% for the quality assessment. All disagreements were resolved through discussion.
Figure 1: Flow diagram of included studies
Study characteristics
The 16 included papers reported results from 15 different studies, with one study reported in two included papers [24, 25] at different follow-up time points.
Of the 15 samples included (Table 1), nine sampled populations in North America [24–32], two in China [33, 34] two in Israel [35, 36], one in Colombia [37] and one in Norway [38]. The earliest study was published in 1985 and the most recent in 2019. The sample size of included studies ranged between 44 and 803 participants. Mean age of samples ranged between 33 and 79 and, except for one study, the majority of participants in each sample were female. Participant groups were defined as those bereaved by natural disasters (four studies), homicide (four studies), suicide (four studies), accidental death (two studies) or armed conflict (one study). One study was longitudinal in design (27), and measured outcomes six months after baseline measurement (at a mean of 1.66 years post-loss). Another study (25) followed-up a sample described in an included cross-sectional analysis [24] but reported different measures, so was essentially a separate cross-sectional analysis and not comparable. . All other studies were cross-sectional in design.
Table 1
Across the 15 different studies, 11 different measures of social support were used (table 2). The Multidimensional Scale of Perceived Social Support (MSPSS) [39] was the most frequently included measure, employed in five studies.
Measures were based on different theoretical approaches to social support, with some distinguishing between perceived and received social support (measuring one or both), and some distinguishing between structural and functional support (measuring one or both), and some developed and validated for specific populations.
Table 2
Across the 15 different studies, 15 different mental health and psychological wellbeing outcomes were measured. The most frequently measured outcomes were post-traumatic stress disorder (PTSD), depression and complicated grief. The remaining measures were of other distinct psychiatric and psychological wellbeing outcomes (table 3). No studies measured service use as an indicator of wellbeing. Where studies measured prevalence of an outcome rather than symptom severity, a cut-off score on an assessment tool was used rather than self-report of an existing clinical diagnosis.
Table 3
Risk of bias
All studies used descriptive single-group designs or included a control that was not analysed comparatively, so were assessed using MMAT criteria for quantitative descriptive studies. Table 4 shows the results of the MMAT risk of bias assessments for included studies. For most studies, the risk of bias was low (11 studies met three or four of the criteria). Two studies met two out of the four criteria with a medium risk of bias. Three studies had a high risk of bias, meeting only one of the criteria. The most frequent source of bias was response rate, where 11 studies did not meet criteria (where response rate was lower than the 60% threshold or was not specified).
Table 4
In addition to the MMAT assessment, we also considered bias in relation to sample size, multiple testing, and confounding. The majority of studies did not report power calculations, and half used sample sizes of under 100 participants. Exploratory approaches were common, with multiple statistical models often used in study analyses, reflecting multiple outcomes and exposure variables. There was also great variation in the degree to which analyses controlled for potential confounding variables, and in the specific variables chosen as potential confounders. The risk of residual confounding in the estimates reported was therefore high.
Summary of findings
Table 5 summarises the overall findings extracted from included studies for each outcome type.
Table 5: Summary of the number of studies indicating an association between social support and each outcome
|
Number of studies indicating an association between social support and outcome
|
Positive association*
|
Partial positive association†
|
No association
|
Negative association
|
Outcome
|
|
|
|
|
Psychiatric
|
PTSD (N=6)
|
4
|
2
|
-
|
-
|
Depression (N=7)
|
4
|
2
|
1
|
-
|
Complicated grief (N=6)
|
2
|
1
|
2
|
1
|
Prolonged grief
(N=1)
|
-
|
-
|
1
|
-
|
Anxiety (N=1)
|
-
|
1
|
-
|
-
|
Suicidal ideation (N=1)
|
1
|
-
|
-
|
-
|
Psychological
|
Emotional distress (N=1)
|
1
|
-
|
-
|
-
|
Grief (N=1)
|
1
|
-
|
-
|
-
|
Grief difficulties (N=1)
|
1
|
-
|
-
|
-
|
Initial impact of event (N=1)
|
-
|
1
|
-
|
-
|
Mental distress (N=1)
|
-
|
-
|
1
|
-
|
Mourning (N=1)
|
1
|
-
|
-
|
-
|
Personal growth (N=1)
|
1
|
-
|
-
|
-
|
Resilience (N=1)
|
1
|
-
|
-
|
-
|
Stress-related growth (N=1)
|
1
|
-
|
-
|
-
|
* all measured social support variables had a significant positive association with the reduced severity of, or reduced likelihood for meeting the threshold of diagnosis for a measured outcome.
† some but not all of the included social support variables had a significant positive association with reduced severity of, or reduced likelihood for meeting the threshold of diagnosis for the measured outcome, with the remaining included variables not significantly associated with the outcome.
Psychiatric Outcomes
Depression (seven studies)
There was limited evidence that social support was associated with reduced risk of meeting the threshold for depression diagnosis or reduced depression symptom severity, with seven small to medium sized studies measuring this outcome. The single longitudinal study included in this review had a high risk of bias and additionally had a small sample size and was exploratory in nature, but did control for baseline outcome measures. This study found no association between the two variables [27].
Four studies reported a positive association between a single measure of social support and depression; two were at a low risk of bias [24, 30], two were at medium risk of bias [29, 31].
Two more exploratory studies reported a partial positive association between social support and depression. A low risk of bias study found that only one (perceived support from friends) of two social support variables in one of three analysis models was cross-sectionally associated with reduced symptom severity [40], with the other 2 models finding no association. A high risk of bias study found that two (grief support and percentage of anticipated negative relationships) of six social support variables correlated significantly with reduced symptom severity [28].
PTSD (six studies)
There was limited evidence that social support was associated with a reduced risk of meeting the threshold for PTSD diagnosis or with reduced symptom severity. All six studies that measured PTSD as an outcome found some evidence of an association between increased social support and reduced severity of/likelihood of meeting threshold for PTSD, however studies were of mixed quality.
In the longitudinal study, one (satisfaction with physical assistance) out of twelve measured social support variables predicted lower symptom severity [27]. One other small, high risk of bias study found a partial positive association, with only one (percentage of actual negative relationships) of out six social support variables correlated with lower symptom severity [28].
Four other small-medium sized studies found a positive association between social support and PTSD. Two of these studies had a low risk of bias [32, 34], one had a medium risk of bias [30] and one had a high risk of bias [37].
Complicated grief [CG] (six studies)
There was mixed evidence regarding whether social support was associated with a reduced risk of meeting the threshold for CG diagnosis or reduced symptom severity, with six studies measuring this outcome. The included longitudinal study found that only one (satisfaction with physical assistance) of twelve social support variables was associated with CG, predicting increased severity of symptoms [27].
Two studies reported a positive association: two medium-sized studies with a low risk of bias reported a positive association between the social support risk of CG [36, 38]. Another study found a partial positive association; this small, high risk of bias study found that two (percentage of actual negative relationships and available support system) of six social support variables was correlated with reduced symptom severity of CG [28].
Two more studies with a low risk of bias found no cross-sectional association between social support and CG; one small [30] and one with a large sample size [33].
In one medium-sized, cross-sectional study at high risk of bias [37] assessed the outcome of prolonged grief, a concept similar to CG, and found no association with social support.
Other psychiatric outcomes (two studies)
The outcome of anxiety was measured in the included longitudinal study [27], where one of twelve measured social support variables at T1 significantly predicted lower levels of anxiety at T2 and the other variables showing no association.
A separate medium-sized study with a medium risk of bias [29] found a significant positive association between a global social support measure and lower levels of suicidal ideation.
Other psychological wellbeing outcomes (eight studies)
Nine separate psychological wellbeing outcomes were measured, demonstrating limited evidence that social support is associated with improved psychological wellbeing.
There was consistent evidence that social support influences positive wellbeing, with three separate studies measuring personal growth, stress-related growth and resilience. A medium-sized study with a medium risk of bias found that increased personal growth was cross-sectionally associated with increased social support [29], and a medium-sized study with a low risk of bias found that increased stress-related growth was cross-sectionally associated with increased social support [36]. Social support mediated the association between traumatic stress and resilience in a small study with a low risk of bias [26].
The similar constructs of grief, mourning, and extent of grief difficulties, were each significantly cross-sectionally associated with social support in two separate exploratory, medium-sized studies, one with a low risk of bias [32] and one with a medium risk of bias [29].
Two studies measured distress with conflicting findings; one small study with a high risk of bias found a positive association between social support and emotional distress [37] whereas a small study with a low risk of bias found no cross-sectional association between social support and mental distress [41].
A single low risk of bias study assessed the initial impact of event (IES; 40) and found that one (perceived support from friends) of two social support variables in one of three analysis models was cross-sectionally associated with reduced impact [40], the other two models finding no association.
Two further psychological outcomes, loneliness [31] and recovery [24], were mentioned as having been measured in the methods sections of separate studies but were not included in statistical analysis models reported.
Subgroup: people bereaved by suicide (four studies)
Four of the cross-sectional studies reported above included only participants who had been bereaved by suicide, each controlling for a range of demographic and health-related variables. Study results consistently found that increased social support was associated with improved wellbeing.
Two medium-sized studies had a low risk of bias; one found a partial positive association between social support and stress-related growth [35] and another found that social support was cross-sectionally associated with a significantly reduced risk of CG [36].
Two other exploratory cross-sectional studies, one small, one medium-sized, with a medium risk of bias demonstrated a positive association between social support and depressive symptoms [29, 31], suicidal ideation [29] and grief difficulties [29].
Other subgroups
No other meaningful patterns of results defined by subgroups became apparent during the process of data synthesis, whether based on type of loss or type of social support measurement. Insufficient information was provided in studies to compare results by relationship type or time since loss.