When does grief become pathological? Evaluation of the ICD-11 diagnostic proposal for prolonged grief in a treatment-seeking sample.

: Prolonged grief disorder (PGD) will be newly included in the ICD-11, while a clinically similar diagnosis, persistent complex bereavement disorder (PCBD), has already been added to the DSM-5. Only few studies have evaluated these criteria-sets for prolonged grief. : The aim of this study was to evaluate the ICD-11 accessory symptom threshold and compare the diagnostic performance of the two criteria-sets in treatment-seeking bereaved persons. : 113 grief treatment-seeking bereaved persons completed the Interview for Prolonged Grief-13. We used receiver operator characteristic analysis to determine an optimum ICD-11 accessory symptom threshold. We calculated diagnostic rates for PGD and PCBD and examined associations of PGD and PCBD caseness with concurrently assessed psychopathology and prolonged grief symptoms assessed one month later. : An ICD-11 threshold of six accessory symptoms distinguished optimally between interview-diagnosed participants with and without prolonged grief. The prevalence of PGD (69%) was significantly higher than that of PCBD (48%) and of PGD with a 6-symptom threshold (47%). PGD caseness was associated with the relation to the deceased, 6-symptom threshold PGD and PCBD caseness with the time since loss. All criteria-sets were linked to concurrent prolonged grief, depression, and general mental distress. PCBD and 6-symptom threshold PGD but not PGD were associated with prolonged grief severity one month later. : The results support the validity of PGD and PCBD but, at the same time, they provide further support for differing prevalence rates. Using an empirically determined ICD-11 accessory symptom threshold could prevent the pathologisation of grief reactions.