Discrimination and structural validity evaluation of Zung self-rating depression scale for pregnant women in China

Abstract

Purpose

The applicability of the Zung self-rating depression scale (SDS) in pregnancy is unknown. We aimed to identify redundant items and evaluate the Zung SDS’s structural validity.

Method

Two samples of pregnant women were invited from two districts in Shanghai (Yangpu sample, n = 6468 and Huangpu sample, n = 402). The Yangpu sample was randomly split into YGroup1/2/3. Item’s properties were evaluated via the item response theory in YGroup1. Exploratory and confirmatory factor analyses were correspondingly executed in YGroup2 and YGroup3. Those items with discrimination parameter (α) lower than 0.65 or factor loading smaller than 0.4 were deleted from the scale. The final structure was validated in the Huangpu sample.

Results

Items 4 (sleep), 7 (weight loss), 8 (constipation) and 9 (tachyarrhythmia) exhibited low discrimination power. Items 2 (diurnal variation), 5 (appetite), 10 (fatigue) and 19 (suicide idea) made a low contribution to all factors. A three-factor model was eventually constructed as cognitive (Items 14, 16, 17, 18 and 20), psychomotor (Items 6, 11 and 12) and affective (Items 1, 3, 13 and 15).

Conclusion

The Zung SDS needs modification before applied to pregnant women in China. The items describing the overlap symptoms of the physical change in pregnancy and mood disorder should be deleted.

Keywords:

• Zung self-rating depression scale
• antenatal depression
• factor analysis
• item response theory
• reliability

Acknowledgements

The authors acknowledged Miss Yan Xu, a PhD student from University of Kentucky, Lexington, OH for her kind help in statistics. The authors also thanked Prof Yan Ding and Miss Shuhua Qian in ObGyn Hospital of Fudan University for their help in data collection.

Ethical approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional (Obstetrics and Gynecology Hospital of Fudan University) and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. Informed consent was obtained from all participants included in the study.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statements

The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.

Additional information

Funding

This work was supported by National Natural Science Foundation of China [NSFC No. 81871183].