Rob B K Wanders1, Klaas J Wardenaar2, Ronald C Kessler3, Brenda W J H Penninx4, Rob R Meijer5, Peter de Jonge2. 1. University of Groningen, University Medical Center Groningen, Interdisciplinary Center Psychopathology and Emotion regulation (ICPE), Groningen, The Netherlands. Electronic address: r.b.k.wanders@umcg.nl. 2. University of Groningen, University Medical Center Groningen, Interdisciplinary Center Psychopathology and Emotion regulation (ICPE), Groningen, The Netherlands. 3. Department of Health Care Policy, Harvard Medical School, Boston, MA, United States. 4. Department of Psychiatry and EMGO Institute for Health and Care Research, VU University Medical Centre, Amsterdam, the Netherlands. 5. University of Groningen, Department of Psychometrics and Statistics, The Netherlands.
Abstract
OBJECTIVE: To investigate the impact of differences in depressive symptom reporting across clinical groups (healthcare setting, chronic illness, depression diagnosis and anxiety diagnosis) on clinical interpretability and comparability of depression scores. METHODS: Participants from the Netherlands Study of Depression and Anxiety (n=2981) completed the self-report Inventory of Depressive Symptomatology (IDS-SR). Differences in depressive symptom reporting between distinct clinical subpopulations were assessed using a Differential Item Functioning (DIF) analysis. The effects of DIF on symptom level were evaluated by examining whether DIF-adjustment had clinically relevant effects. RESULTS: Significant DIF was detected across all tested clinical subpopulation groupings. Clinically relevant DIF was found on the symptom level for 13 IDS-SR items. However, impact of DIF on the aggregate level ranged from small to negligible: adjustment for DIF only led to salient changes in aggregate scores for 0.2-12.7% of individuals across tested sources of DIF. CONCLUSION: Differences in endorsement patterns of depressive symptoms were observed across clinical populations, challenging the assumptions regarding the measurement properties of self-reported depression. However, effects of DIF on the aggregate level of IDS-SR total scores were found to be minimal and not clinically important. The IDS-SR thus seems robust against DIF across clinical populations.
OBJECTIVE: To investigate the impact of differences in depressive symptom reporting across clinical groups (healthcare setting, chronic illness, depression diagnosis and anxiety diagnosis) on clinical interpretability and comparability of depression scores. METHODS:Participants from the Netherlands Study of Depression and Anxiety (n=2981) completed the self-report Inventory of Depressive Symptomatology (IDS-SR). Differences in depressive symptom reporting between distinct clinical subpopulations were assessed using a Differential Item Functioning (DIF) analysis. The effects of DIF on symptom level were evaluated by examining whether DIF-adjustment had clinically relevant effects. RESULTS: Significant DIF was detected across all tested clinical subpopulation groupings. Clinically relevant DIF was found on the symptom level for 13 IDS-SR items. However, impact of DIF on the aggregate level ranged from small to negligible: adjustment for DIF only led to salient changes in aggregate scores for 0.2-12.7% of individuals across tested sources of DIF. CONCLUSION: Differences in endorsement patterns of depressive symptoms were observed across clinical populations, challenging the assumptions regarding the measurement properties of self-reported depression. However, effects of DIF on the aggregate level of IDS-SR total scores were found to be minimal and not clinically important. The IDS-SR thus seems robust against DIF across clinical populations.
Authors: Klaas J Wardenaar; Rob B K Wanders; Annelieke M Roest; Rob R Meijer; Peter De Jonge Journal: Int J Methods Psychiatr Res Date: 2015-05-21 Impact factor: 4.035
Authors: Karon F Cook; Michael A Kallen; Charles Bombardier; Alyssa M Bamer; Seung W Choi; Jiseon Kim; Rana Salem; Dagmar Amtmann Journal: Qual Life Res Date: 2016-07-14 Impact factor: 4.147