Differential reporting of depressive symptoms across distinct clinical subpopulations: What DIFference does it make?

Rob B. K. Wanders*, Klaas J. Wardenaar, Ronald C. Kessler, Brenda W. J. H. Penninx, Rob Meijer, Peter de Jonge

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

11 Citations (Scopus)

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.

Original languageEnglish
Pages (from-to)130-136
Number of pages7
JournalJournal of Psychosomatic Research
Volume78
Issue number2
DOIs
Publication statusPublished - Feb-2015

Keywords

  • Depression
  • Measurement
  • IDS-SR
  • Item response theory
  • Differential item functioning
  • ITEM RESPONSE THEORY
  • QUALITY-OF-LIFE
  • LOGISTIC-REGRESSION
  • R PACKAGE
  • SCALE
  • ANXIETY
  • PSYCHOPATHOLOGY
  • POPULATION
  • DISORDERS
  • CRITERIA

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