• Only a small body of evidence has addressed screening approaches. There was insufficient evidence for evidence statements regarding patient experience, validity and diagnostic accuracy of the screening tool or approach, or adverse events associated with the screening process.
• A small body of evidence has addressed the identification of bereaved people at risk or with grief disorder; and reports positive diagnostic accuracy of the Inventory of Complicated Grief (ICG). However, none of the identified studies used a DSM or ICD grief disorder diagnosis as the reference standard.
• A substantial body of evidence addressed psychotherapy, pharmacotherapy, expert-facilitated support groups, peer support, self-help approaches, and other interventions (writing and music, comprehensive support, integrative medicine and CAM) but the strength of evidence (SoE) was limited for many interventions. No study evaluated spiritual counselling.
• We found moderate SoE for the beneficial effect of psychotherapy on severity of grief disorder, grief symptoms, and depression symptoms and expert-facilitated support groups on grief symptoms and depression symptoms.
• There is a small body of evidence reporting on patients diagnosed with grief disorders; with low SoE for the beneficial effect of psychotherapy on grief disorder and grief symptoms.

Objectives. Recently bereaved individuals face higher medical risks, including increased risk of morbidity and mortality, increased risk of suicide, and lower functional status and quality of life. This systematic review assesses the available evidence on screening, diagnosing, and treating those experiencing prolonged grief. Findings from this review will inform an independent subject matter expert panel that will assess the feasibility of developing consensus-based quality standards for high quality bereavement and grief care.

Data sources. We searched 14 databases through September 8, 2023, set up a submission for supplemental evidence portal, reference-mined pertinent reviews, and contacted experts.

Review methods. We followed a registered and published protocol, key informants and a multidisciplinary expert panel provided input. We followed the EPC methods guide, assessed risk of bias and applicability, and evaluated strength of evidence (SoE).

Results. In total, 191 studies met inclusion criteria (5 screening, 11 diagnosing, 172 grief interventions, and 3 grief disorder treatment). We identified numerous interventions for grief, including psychotherapy, pharmacotherapy, expert-facilitated support groups, peer-support, self-help interventions, and other interventions. From these we found moderate SoE of positive effects of psychotherapy on grief disorder symptoms, grief outcomes, and depression symptoms. We also found moderate SoE for positive effects of expert-facilitated support groups on grief symptoms and depression symptoms. Few studies reported on unintended consequences or harms of interventions.

We did not identify studies that evaluated universal screening (assessing everyone for grief), and very few and diverse studies evaluated a targeted screening approach for recently bereaved people. The small body of evidence evaluating the diagnostic accuracy of tools to identify grief and risk of grief disorder did not use a DSM or ICD grief disorder diagnosis as the reference standard. There was low SoE for good sensitivity, specificity, and AUC for the Inventory of Complicated Grief; evidence was insufficient for other tools. The body of evidence for patients diagnosed with grief disorders is small. We found low SoE for the beneficial effect of psychotherapy on grief disorder and grief symptoms.

Conclusions. A clinical diagnosis specific to grief has only recently been introduced and more research is needed on effective screening approaches and tools for diagnostic accuracy. A substantial body of evidence demonstrates positive effects of grief interventions on grief and depression symptoms, but more data are needed on the presence or absence of adverse events. Future research needs to assess the effects of treatment for people with a clinically diagnosed grief disorder.