Measuring posttraumatic stress following childbirth: a critical evaluation of instruments.
OBJECTIVE
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 alpha = 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 rho = 0.78), agreement between the instruments on the identification of PTSD cases is low (kappa = 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.
Department of Obstetrics and Gynecology, University Medical Center Groningen, Groningen, The Netherlands. c.a.i.stramrood@og.umcg.nl
Claire A I
CA
Stramrood
Elisabeth M J
EM
Huis In 't Veld
Maria G
MG
Van Pampus
Leonard W A R
LW
Berger
Ad J J M
AJ
Vingerhoets
Willibrord C M Weijmar
WC
Schultz
Paul P
PP
Van den Berg
Eric L P
EL
Van Sonderen
K Marieke
KM
Paarlberg
D000328:Adult; D005260:Female; D006801:Humans; D008016:Life Change Events; D009035:Mothers / Q000523:psychology*; D036801:Parturition / Q000523:psychology; D049590:Postpartum Period / Q000523:psychology*; D011247:Pregnancy; D011256:Pregnancy Outcome / Q000523:psychology*; D011594:Psychometrics; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013313:Stress Disorders, Post-Traumatic / Q000175:diagnosis*; D011795:Surveys and Questionnaires; D055815:Young Adult