A validation of the International Grief Questionnaire with Clinical Checks (IGQ‐CC) in earthquake‐bereaved adults in Türkiye

Assessment of prolonged grief disorder (PGD) often relies on self-report measures, which may lead to false positives when normal grief reactions are interpreted as clinically relevant. This may result in unnecessary referrals and inflated prevalence estimates. The International Grief Questionnaire with clinical checks (IGQ-CC) was developed to address this limitation by integrating brief, interview-like verification steps into a self-report format. This study examined the psychometric properties of the IGQ-CC in earthquake-bereaved adults in Türkiye and evaluated the impact of clinical checks on symptom endorsement and PGD prevalence estimates. The sample included 748 adults bereaved by the February 6, 2023, earthquakes. Participants also completed self-report measures of depression, anxiety, prolonged grief, posttraumatic stress disorder (PTSD), and somatization. Confirmatory factor analysis (CFA) was conducted to examine the factorial structure of the measure. Clinical checks reduced endorsement rates across all items by 12.1%-18.2%. Stepwise application of diagnostic criteria (symptom presence, clinical checks, functional impairment, and cultural considerations) reduced the estimated PGD prevalence from 49.1% to 39.7%. CFA supported a correlated two-factor structure distinguishing core and associated symptoms for both Likert-scored and clinically verified items. Subscale reliability was excellent, ω = .89-.92, and the IGQ-CC showed strong convergent validity with PGD severity, r = .75, and PTSD symptoms, r = .62. These findings support the reliability and validity of the IGQ-CC for assessing PGD in disaster-affected populations. Clinical checks may help reduce false-positive classifications and improve prevalence estimates in mass bereavement contexts.