Prolonged grief disorder (PGD) and depression are common emotional disorders influencing bereaved caregivers’ quality of life (QOL). However, the conceptual distinctiveness and temporal relationship of PGD and depression have been partially and not established, respectively. To fill these knowledge gaps, we conducted this longitudinal study.
Our convenience sample included 291 caregivers of terminally ill cancer patients. Caregivers’ PGD, depression, and psychological QOL were measured 6, 13, 18, and 24 months postloss using the Prolonged Grief-13 scale (PG-13), Center for Epidemiologic Studies-Depression (CESD) scale, and Short Form-36 Health Survey mental health summary, respectively. We examined the associations of PGD and depression with psychological QOL by an incremental validity test, thereby clarifying their conceptual distinctiveness. The temporal relationship between PGD and depression was examined by longitudinal, lower-level mediation analysis with a lagged approach.
After the variance in psychological QOL was significantly explained by CESD scores (pseudo R2=44.19%, p<.001), PGD significantly, incrementally increased the explained variance in psychological QOL (pseudo R2=.21%, p<.001), confirming the distinction between PGD and depression. Lower-level mediation analysis showed that CESD scores (depressive symptoms) mediated 90% of the relationship between time and PG-13 scores, whereas PG-13 scores only mediated 76% of the relationship between time and CESD scores. This result indicates that CESD scores assessed at a previous time mediated caregivers’ current PGD during bereavement rather than vice versa.
PGD and depression are conceptually distinct disorders, and depression precedes development of PGD. Clinicians must distinguish between the two disorders and appropriately manage bereaved caregivers’ depressive symptoms. Alleviating caregivers’ depressive symptoms will prevent development of PGD, thus improving QOL.
Clinical trial identification
(NHRI-EX107-10704PI) and Ministry of Science and Technology (MOST 104-2314-B-182-027-MY3), National Science Council (NSC 96-2314-B-182-029-MY2), and Chang Gung Memorial Hospital (BMRP888).
Legal entity responsible for the study
Chang Gung University.
Ministry of Science and Technology, National Science Council, and Chang Gung Memorial Hospital.
All authors have declared no conflicts of interest.