Psychometric properties of the PG-13-R scale to assess prolonged grief disorder among bereaved Iranian adults

OBJECTIVES

The PG-13-Revised (PG-13-R) is a self-report measure to assess prolonged grief disorder (PGD) in terms of Diagnostic and Statistical Manual of Mental Disorders, fifth revision, Text Revision. This measure has been shown to yield good psychometric properties in Western samples. This study aimed to evaluate the psychometric properties of the Persian PG-13-R.

METHODS

Three hundred forty-seven individuals (209 women and 138 men) fully completed the scales. The participants were recruited using convenience sampling. The confirmatory factor analysis (CFA), convergent and divergent validity, and reliability of the Persian version of the PG-13-R were evaluated.

RESULTS

CFA results of a unidimensional model support the construct validity of this version of the PG-13-R. The results of this study demonstrated that this version of the PG-13-R has internal consistency reliability (omega coefficient of 0.93), and the test-retest reliability with an interval of 6 weeks was 0.89. The convergent and divergent validity was shown with significant correlations between the PG-13-R and measures of depression, PTSD, functional impairment, and hope.

SIGNIFICANCE OF RESULTS

Overall, the Persian version of the PG-13-R showed good psychometric properties in the Iranian population.

Validation of the new DSM-5-TR criteria for prolonged grief disorder and the PG-13-Revised (PG-13-R) scale

Although the concept of pathological grief dates back at least as far as Freud's "Mourning and Melancholia", there has been opposition to its recognition as a distinct mental disorder. Resistance has been overcome by evidence demonstrating that distinctive symptoms of prolonged grief disorder (PGD) - an attachment disturbance featuring yearning for the deceased, loss of meaning and identity disruption - can endure, prove distressing and disabling, and require targeted treatment. In acknowledgement of this evidence, the American Psychiatric Association Assembly has recently voted to include PGD as a new mental disorder in the DSM-5-TR. We tested the validity of the new DSM criteria for PGD and of an adapted version of our PG-13 scale, the PG-13-Revised (PG-13-R), designed to map onto these criteria, using data from investigations conducted at Yale University (N=270), Utrecht University (N=163) and Oxford University (N=239). Baseline assessments were performed at 12-24 months post-loss; follow-up assessments took place 5.3-12.0 months later. Results indicated that the PG-13-R grief symptoms represent a unidimensional construct, with high degrees of internal consistency (Cronbach's alpha = 0.83, 0.90 and 0.93, for Yale, Utrecht and Oxford, respectively). The DSM PGD diagnosis was distinct from post-traumatic stress disorder (phi=0.12), major depressive disorder (phi=0.25) and generalized anxiety disorder (phi=0.26) at baseline. Temporal stability was remarkable for this diagnosis (r=0.86, p<0.001). Kappa agreement between a PG-13-R threshold symptom summary score of 30 and the DSM symptom criterion for PGD was 0.70-0.89 across the datasets. Both the DSM PGD diagnosis and the PG-13-R symptom summary score at baseline were significantly associated (p<0.05) with symptoms and diagnoses of major depressive disorder, post-traumatic stress disorder and/or generalized anxiety disorder, suicidal ideation, worse quality of life and functional impairments at baseline and at follow-up, in the Yale, Utrecht and Oxford datasets. Overall, the DSM-5-TR criteria for PGD and the PG-13-R both proved reliable and valid measures for the classification of bereaved individuals with maladaptive grief responses.