Written approval to use and translate the W-DEQ-A was obtained from the original author.
The W-DEQ-A was independently evaluated by two bilingual obstetrics researchers, with all items deemed appropriate. Forward translation of the W-DEQ-A to Chinese was then performed separately. The two translated questionnaires were reviewed in a meeting, and a single version was reached after going through items of inconsistency. Back-translation was performed by another bilingual professional who had no access to the original questionnaire. The original and back-translated versions were compared for any issues regarding accuracy and understanding in the Chinese cultural context by another researcher.A panel consisting of the researchers was held to review and settle on the finalised Chinese version.
After ensuring that there were no major discrepancies, the questionnaire was then distributed to a pilot group of 20women at the obstetric ward for feedback. The group found the questionnaire items appropriate, and they were able to comprehend and fill in the translated W-DEQ-A without problems.
Recruitment and study phase
Recruitment of participants occurred between Marchand June 2020. All Chinese women attending antenatal booking visit atTsan Yuk hospital in Hong Kong were invited to join the study to validate the W-DEQ-A.
Exclusion criteria included those under 18 years old, those withintellectual or mental impairment making completion of questionnaire challenging, refusal by women, incompletequestionnaires, and women who had a test-retest interval beyond 20 days. Women were recruited by the research team and dedicated research assistants. Written consents were obtained, and all women were given verbal and written explanations.
The state-trait anxiety inventory state (STAI) and Edinburghpostpartum depression scale (EPDS) were used as assessments of the validity of the Chinese version of the W-DEQ-A. Hong Kong Chinese versions arealready available for both tools and validated for use (27, 28).
The STAI consists of 2 subscales with 20 items each on a 4-point Likert scale, which examines 2 dimensions of anxiety, namely state and trait anxiety. It is one of the most frequently utilised self-report measuresto assess anxiety during pregnancy(29). It has demonstrated high validity and reliability among Asian countries including Hong Kong(30, 31). The score can range from 20-80 for each subscale, with higher scores corresponding to a higher level of anxiety.
The EPDS is the most widely adopted screening tool for both antenatal and postnatal depression worldwide(29, 32). It consists of 10 self-reported questions, where each item is rated from 0 (normal) to 3 (severe), totalling to a maximum score of 30. It demonstrates satisfactory psychometric properties(28). The Chinese version of EPDS is currently utilised among public hospitals in Hong Kong.
The Chinese versions of the W-DEQ-A, STAI and EPDS were distributed for completion by participating women. Basic demographics and the preferred mode of delivery in their current pregnancy were collected. They were required to fill in the same questionnaires via an online platform about 2 weeks after initial completion to establish test-retest reliability.
Basic demographics including age, educational and marital status, past psychiatric history and social history, were obtained from their medical records. Women who had stable antenatal course before the repeat test were used in the analysis of the test-retest reliability. Those who had received psychiatric interventions in between were excluded from the test-retest reliability analysis.
Statistical analysis and sample size calculation
The subject-to-item ratio of any measurement scale wassuggested to be 5:1 (33, 34). As there were 33 items in W-DEQ-A, a sample size of 165 (33 x 5) was required to fulfil the criteria. A sample size of 165pregnant women would be sufficient to fulfil the aforementioned criteria and to assess the correlation of the other questionnaires with the W-DEQ-A.
Statistical analysis was performed by using SPSS Statistics (Version 26.0. Armonk, NY: IBM Corp). W-DEQ-A score ≥ 85 at their first visit was defined as women having FOC, while score of ≥ 100 indicated severe FOC. Data were presented as mean and standard deviation (SD) for continuous data or n and percentage for categorical data. Differences according to demographic or obstetric characteristics were analysed by student’s t test or Mann-Whitney test for continuous data and chi-square test for categorical data. Exploratory factor analysis was conducted to analyse the factor validity. Principal component analysis with varimax rotation was performed on 33 items, and the number of factors were defined by the use of scree plots.
Internal consistency of W-DEQ-A and its subscales was assessed using Cronbach’s alpha test, and the scores from their first visit was used. A Cronbach’s alpha coefficient of >0.7 was considered as adequate internal consistency(35). The test-retest reliability was assessed by Intraclass Correlation Coefficient (ICC). An ICC value of 0.4 or less was considered as poor to fair agreement, 0.41 to 0.6 as moderate agreement, 0.61 to 0.8 as good agreement and 0.81-1.0 as excellent agreement (36).The convergent validity of W-DEQ-A was estimated by Pearson’s correlation with STAI and EPDS. A p value <0.05 was considered statistically significant.