I have heard that some forms of mutual support groups for bereavement may be ineffective, and may do harm. I am aware of the research on one to one counselling efficacy, but not group work.
A little dated, but a good start, is the following article abstracted on PubMed
J Soc Work End Life Palliat Care. 2006;2(1):29-53.
Grief support groups used by few--are bereavement needs being met?
Steiner CS1.
Abstract
Few adult bereaved attend closed grief support groups, yet many of those who do attend say they are extremely helpful. This research explores factors influencing support group attendance, and the extent to which bereavement support needs are being met. Focus group discussions reveal that a broad scope of sources of support is available to the bereaved. Results show what is seen as unhelpful to them, and what might be more helpful to them. The study indicates many adult bereaved suffer from an overall lack of support and would benefit from more caring overtures from those around them. Findings from this small frontline hospice bereavement study point toward ideas for adjustments in support groups and innovative bereavement education and programming.
PMID:
17387081
DOI:
10.1300/J457v02n01_04
[Indexed for MEDLINE]
Currier, J. M., Neimeyer, R. A., & Berman, J. S. (2008). The effectiveness of psychotherapeutic interventions for bereaved persons: A comprehensive quantitative review. Psychological Bulletin, 134(5), 648-661.
http://dx.doi.org/10.1037/0033-2909.134.5.648
Abstract
Previous quantitative reviews of research on psychotherapeutic interventions for bereaved persons have yielded divergent findings and have not included many of the available controlled outcome studies. This meta-analysis summarizes results from 61 controlled studies to offer a more comprehensive integration of this literature. This review examined (a) the absolute effectiveness of bereavement interventions immediately following intervention and at follow-up assessments, (b) several of the clinically and theoretically relevant moderators of outcome, and (c) change over time among recipients of the interventions and individuals in no-intervention control groups. Overall, analyses showed that interventions had a small effect at posttreatment but no statistically significant benefit at follow-up. However, interventions that exclusively targeted grievers displaying marked difficulties adapting to loss had outcomes that compare favorably with psychotherapies for other difficulties. Other evidence suggested that the discouraging results for studies failing to screen for indications of distress could be attributed to a tendency among controls to improve naturally over time. The findings of the review underscore the importance of attending to the targeted population in the practice and study of psychotherapeutic interventions for bereaved persons. (PsycINFO Database Record (c) 2016 APA, all rights reserved)
Allumbaugh, D. L., & Hoyt, W. T. (1999). Effectiveness of grief therapy: A meta-analysis. Journal of Counseling Psychology, 46(3), 370-380.
http://dx.doi.org/10.1037/0022-0167.46.3.370
Abstract
This meta-analysis addressed the question of how effective grief therapy is and for whom, using B. J. Becker's (1988) techniques for analyzing standardized mean-change scores. Analyses were based on 35 studies (N = 2,284), with a weighted mean effect size (ES) of δ+ = 0.43 (95% confidence interval = 0.33 to 0.52). Clients in no-treatment control groups showed little improvement (d= = 0.06), possibly because of the relatively long delay between loss and treatment in most studies (mean delay = 27 months). Moderators of treatment efficacy included time since loss and relationship to the deceased. Client selection procedures, a methodological factor not originally coded in this meta-analysis, appeared to contribute strongly to variability in ESs: a small number of studies involving self-selected clients produced relatively large ESs, whereas the majority of studies involving clients recruited by the investigators produced ESs in the small to moderate range. (PsycINFO Database Record (c) 2016 APA, all rights reserved)
There is little recent research on the topic. A nice online blog, but my browser won't let me copy the link. But if you Google grief support groups harmful quite a bit of helpful stuff appears.
not exactly answering your question, but the Emotional Logic Centre have some very good material available, not sure what Trevor Griffiths has published, based in Devon, been going 20 years
Näppä, U., Lundgren, A. B., & Axelsson, B. (2016). The effect of bereavement groups on grief, anxiety, and depression-a controlled, prospective intervention study. BMC palliative care, 15(1), 58.
These relate to where parents attend support groups:
Umphrey, L. R., & Cacciatore, J. (2011). Coping with the ultimate deprivation: Narrative themes in a parental bereavement support group. OMEGA-Journal of Death and Dying, 63(2), 141-160.
Toller, P. W. (2005). Negotiation of dialectical contradictions by parents who have experienced the death of a child. Journal of Applied Communication Research, 33(1), 46-66.