The total number of citations identified in the database searches in April 2013 was 1706. Following the screening process, 371 references were selected for further review of full texts. After examination of full texts, a total of 15 studies were identified that evaluated the effectiveness of bereavement interventions with parentally bereaved children [25,26,27,28,29,30,31,32,33,34,35,36,37,38,39]. We identified an additional study from checking of the reference lists . The number of citations generated in the updated search in November 2015 was 921. Of these five citations were reviewed in full texts. An additional relevant study was identified , resulting in a total of 17 selected studies for the review, see Fig. 1 below.
The included 17 studies were published between 1985 and 2015, the majority, 13 were published after 1999. Most studies were conducted in the United States [26, 27, 29,30,31,32,33,34,35,36,37,38,39, 41]; two in England [25, 40], and another was an international collaborative study involving Iran, UK and Norway .
Quality of included studies
The studies differed; they were based on different study designs, contained a variety of outcome measures and varied in quality. According to our quality grading criteria (Table 1) [18,19,20] 13 studies provided strong evidence. These studies were randomized controlled trials involving validated measures. Three studies provided fairly strong evidence and one study provided weaker evidence [18,19,20]. Two of the included bereavement interventions were evaluated with a population of more than 100 children. Namely, “The Parent Guidance Program”  and “The Family Bereavement Program” [27, 29, 30, 33,34,35, 37, 39, 41]. One of the interventions, Family Therapy sessions, was tested in two papers [25, 40] and one, The Family Bereavement Program, in as many as ten papers [27, 29, 30, 33,34,35, 37,38,39, 41].
One study employed a quasi-experimental design  and one study had a pre-test/post-test design , the others were randomized controlled trials. What the intervention was compared with varied: no intervention [25, 28, 40]; delayed treatment [31, 32]; a telephone support intervention ; and a self-study program [27, 29, 30, 33,34,35, 37,38,39, 41].
The core concepts addressed in the outcome measures were:
Children’s health, in particular their mental health (internalization, externalization, coping, stress, cortisol-levels)
Children’s grief symptoms (traumatic grief, problematic grief)
Children’s behaviour and school problems
Children’s concepts of death and communication about the deceased parent
Parenting (communication, caregiver-child relationship, parental warmth, acceptance, consistent discipline)
Caregiver’s mental health
Fifty different outcome measures were employed. We present the most commonly reported outcomes in the included studies which focus on children’s health, behaviour, grief, self-esteem, parenting factors and caregivers’ mental health [42,43,44,45,46,47,48,49,50,51,52,53,54] (see Table 2 below).
A key research question for this review is: What types of support interventions were evaluated in the studies? We found studies varied in their theoretical under-pinning and aim. They also took various forms: group interventions for the children [28, 36], family interventions [25, 27, 29, 30, 32,33,34,35, 37,38,39,40,41], parental guidance , and camp activities for children .
Some interventions were designed based on resilience, risk and protective factors for parentally bereaved children [27, 29, 30, 32,33,34,35, 37,38,39, 41]. Others were based on theory of trauma and/or the grieving process [28, 31]; psycho-education ; psychodynamic theory ; and attachment theory [25, 40]. To a large extent, the interventions were directed towards children at an early stage in their grief process. “The Family Bereavement Program” and “The Parent Guidance Program” were explicitly intended to be preventive interventions [26, 33]. However, the intervention “Writing for recovery” was directed at refugee children with high symptoms of traumatic grief . For some of the refugee children, many years had passed since their parents died.
In three of the studies, the interventions were primarily directed at the bereaved child in the form of support groups and/or camp activities [28, 31, 36]. The intentions in these studies were: to provide emotional support; to normalize the children’s experiences after the loss; to provide a safe environment where the child can express emotions and thoughts; to facilitate the child’s grieving process and to aim to improve the child’s physical and mental health. For further description of the interventions, see Table 3.
In the majority of the included studies, the interventions were directed at both the child and their remaining caregiver [25,26,27, 29, 30, 32,33,34,35, 37,38,39,40,41]. The intentions in the included studies were: to provide support for the children and their caregivers; to improve family communication and the caregiver–child relationship; to facilitate participants’ grieving process; to improve their health; strengthen parenting; increase stability and predictability for the children; and to reduce the occurrence of negative events among the children (see Table 3).
In general, the interventions were brief. The shortest program was “Writing for recovery”, involving two 15-min sessions in school during three consecutive days, each day consisted of two sessions (i.e. six 15-min sessions and a total of 90 min) . The camp-based program “CampMAGIC” was delivered over a weekend [31, 55]. The longest, “The Parent Guidance Program” lasted a year, it began when the parent was ill, and continued during the terminal illness and at least 6 months after the parent’s death . It involved at least six sessions during the terminal illness and six after the parent had died. The other interventions were based on a total of 6–14 sessions (see Table 3 for more details).
All interventions were professionally led, in most cases by social workers or counsellors with extensive experience of working with child guidance, grief or psychiatry. The highest educational attainment of professionals were those who led “The Family Bereavement Program”, who had at least a master’s degree . In several studies the intervention leaders received supervision in the implementation of the support program [26, 32, 33, 36].
The included interventions in this review were directed at children from school age up to 18 years of age. This is with the exception of two studies where younger children (0–16) were involved in family therapy sessions [25, 40]. Most of the studies concerned children who had experienced a parental death from a range of causes, namely illness, accident, suicide or homicide [25, 27, 29, 30, 32,33,34,35,36,37,38,39,40,41]. Commonly parents died because of an illness (65–82%), thereafter due to an accident (15–20%) or suicide/homicide (10–14%). In most studies there was a lack of information about what kind of illness the parent suffered from, where there was information, diseases included those of the heart and cancer [25, 32, 40]. One study compared intervention effects for children who had lost a parent to expected versus unexpected deaths . One study focused on children during their parent’s terminal cancer illness as well as after the parent’s death . Finally one study focused on support directed at refugee adolescents who had lost their parents in war . Except for this evaluation directed at refugee children from Afghanistan, the majority of included studies had samples that were diverse in ethnicity, including for example Caucasian, Hispanic, African American, Native American, Asian/Pacific and other ethnicities .
In the studies, the most common deceased parent was the child’s father with the remaining caregiver being the mother. In two of the studies, women as remaining caregivers were over-represented as participants in the study populations [32, 36]. In one study 86% of the deceased parents were fathers and 14% mothers . In another study, fathers as remaining caregivers only represented 5 % of the sample .
Effectiveness of the interventions
Another key research question for this review was: What is known about the effects of support interventions that are targeted at/or include support for parentally bereaved children? The included studies were analysed and summarized in a matrix. The results are presented in table form (see Table 4 below). There were 12 studies that analysed effects within and between trial arms, while five studies analysed moderating and mediating factors. The latter are excluded from the analysis of effects in Table 4, but are nevertheless informative and are therefore included in the article. Our focus is on comparing differences between groups, but we have also chosen to present results within groups in Table 4, as this may be relevant from a benchmarking perspective, both for researchers and clinicians . The results from the analyses of included studies revealed positive effects of the support interventions both for the children and their remaining caregivers in several areas.
There were two studies with strong evidence (from robust studies, see definition in Table 1, Grade criteria) that showed large effects between groups: for children’s traumatic grief ; and parent’s feelings of being supported .
Four studies showed medium effects between groups. Two studies with strong evidence showed medium effects for the parents: for parental warmth ; positive parenting ; parent’s mental health ; and for grief discussions in the family . The following studies with fairly strong evidence showed medium effects: for children’s traumatic grief symptoms ; restlessness ; and children’s health . One study with fairly strong evidence showed medium effects for parental depression .
Some studies showed small effects between groups. The following studies with strong evidence showed small effects: for children’s symptoms of intrusive grief ; children’s PTSD symptoms ; self-esteem [26, 33, 35]; anxiety ; anxiety (girls) ; depression (girls) ; behaviour problems ; social competence ; externalizing [33, 35]; externalizing (girls) ; internalizing ; internalizing (girls) ; cortisol level before and after a conflict discussion task ; negative events ; negative thoughts ; control beliefs ; positive coping ; inhibition ; perceived parenting . One study with strong evidence showed small effects for parent’s depression ; mental health ; demoralization ; and positive parenting . The following studies with fairly strong evidence showed small effects: for children’s behaviour problems [25, 40]; sleep problems ; nail-biting ; talking about the dead parent [25, 40]; and school problems [25, 40].
No effects and negative effects
There were a few studies that failed to reveal any effect on measures at any of the post-test or subsequent follow-up test periods. With “No effect” we mean studies where the between group effect size were on Cohen’s d between 0.00 and 0.19 and the effect size calculated as Phi between 0.00 and 0.09. The following studies with strong evidence showed no effects on depression  and present grief . One study did not show effects for the subgroup boys on the measures anxiety, depression, internalizing and externalizing .
Finally one study showed a small but negative effect for boys’ externalizing behaviour (−0.22), which means that the reduction of externalizing behaviour in boys 11 months post intervention was less in the intervention group than in the control group .