Measuring posttraumatic stress following childbirth: a critical evaluation of instruments

Abstract

Objectives. To evaluate instruments used to assess posttraumatic stress disorder (PTSD) following childbirth with both quantitative (reliability analysis and factor analysis) and qualitative (comparison of operationalization) techniques.

Methods. An unselected population of 428 women completed the Traumatic Event Scale-B (TES-B) and the PTSD Symptom Scale-Self Report (PSS-SR) 2–6 months after delivery.

Results. Assessment of internal consistency yielded similar results for the TES-B and PSS-SR (Cronbach's α = 0.87 and 0.82, respectively). Factor analysis revealed two rather than three DSM-IV symptom categories for both instruments: childbirth-related factors (re-experiencing/ avoidance) and symptoms of depression and anxiety (numbing/ hyperarousal). Although the TES-B and the PSS-SR sum-scores show a strong relationship (Spearmans ρ = 0.78), agreement between the instruments on the identification of PTSD cases is low (κ = 0.24); discrepancy between TES-B and PSS-SR is largely due to differences in instruction to respondents, formulation of items, answer categories, and cut-off values.

Conclusions. Large operationalization differences between TES-B and PSS-SR have been identified, i.e., in the formulation of questions, answer categories, cut-off values and instructions to respondents. Comparison between studies using different instruments for measuring PTSD following childbirth should be done with utmost caution.

Keywords:

• Posttraumatic stress disorder
• psychometrics
• instruments
• operationalization
• childbirth
• postpartum

Acknowledgments

The authors thank the participating women and the four participating midwifery practices for their cooperation: Verloskundigenpraktijk Doevendans (Apeldoorn), Verloskundige Praktijk Vita (Breda), Verloskundigcentrum (Breda), Verloskundige Stadspraktijk (Groningen). This study was supported by the Dutch Society of Psychosomatic Obstetrics and Gynecology, working party of the Dutch Society of Obstetrics and Gynecology.