Study design
Working with feedback from patient and public involvement (PPI) representatives, we designed and developed a 3-session group-based intervention for anxiety, led by midwives and supported by a psychological practitioner. This drew on core CBT principles and learning from the team that developed the Towards Parenthood intervention (48). Following the development of the intervention, it was piloted, then refined using participant feedback and additional input from health professionals and service users.
We conducted a feasibility RCT comparing the group intervention for prenatal anxiety plus TAU (intervention group) with TAU-only (control group). The protocol for this study has been previously published (49) and follows CONSORT (50) and SPIRIT (51) guidelines for reporting clinical trial protocols. The trial was prospectively registered, 29/10/2014, ISRCTN 95282830.
Ethical approval and Consent to Participate
The trial received ethical approval from the London – Riverside National Research Ethics Service on 15 April 2014 (Research Ethics Committee reference number: 14/LO/0339). The authors assert that all procedures contributing to this work complied with the ethical standards of the relevant national and institutional committees on human experimentation and with the Helsinki Declaration of 1975, as revised in 2008. Participants were identified by a study-specific participant number in all databases (49).
Feasibility Criteria
The primary outcome was the feasibility of the study and intervention. We did not set a priori markers for feasibility, but accessed feasibility against commonly used criteria. These criteria include ≥ 80% trial retention and ≥ 70% treatment engagement (52, 53). Further, we compared treatment adherence to the ACORN intervention against NHS England’s primary care mental health services (Increasing Access to Psychological Therapies; IAPT) definition (2 or more sessions) and performance (27.5% adherence) (54).
As a secondary marker, we also included potential efficacy as a feasibility criteria. ACORN is a brief intervention for individuals with mild-to-moderate levels of anxiety. Consistent with other, similar interventions (e.g., (53), we expected at least a least a small baseline to post-treatment between-group effect size. We also expected that the intervention effect would be sustained over the follow-up period.
Inclusion Criteria
Participants were recruited through National Health Service (NHS) prenatal scanning clinics at their 12-week scan at sites in London and Exeter, UK (49). Participants were either approached directly by a research assistant in the clinic, or an administrative assistant provided them with the screen and study information. Eligible participants were pregnant women who had no previous children, were entering their second trimester and aged 18 years and over. Women were invited to participate if they scored in the top quartile of scores from normed data on the Generalised Anxiety Disorder 7-item scale (GAD-7; (55) at screening (GAD-7 = 7 or above). The GAD-7 is a 7-item self-report screening measure for general anxiety symptoms which is widely used in clinical practice and research and is validated for use in pregnancy (56).
Partners of women who consented to take part in the study were also invited to participate in the treatment alongside the pregnant woman, the primary participant.
Potential participants were excluded if: they had insufficient understanding of English to complete the intervention or outcome measures, or they had a significant illness or disability that would make it difficult for them to participate.
Procedures and Randomisation
After completing the screening questionnaire for anxiety (GAD-7; (55) and demographic questions in the prenatal scanning clinic, women who met eligibility criteria were invited to participate. The woman’s midwife was alerted if she had a positive GAD-7 screening score. Normal practice would have involved the midwife following up on the screen and if agreed with the woman, a referral would be made to perinatal mental health services. Upon completion of a written consent form and baseline questionnaire measures, including GAD-7 and the Edinburgh Postnatal Depression Scale (EPDS; (57), eligible participants were randomised on a 1:1 basis to the intervention or control group using a sealed envelope method, managed by a staff member in a separate research group (see Figure 1).
Questionnaire measures were collected at baseline (T1), post-intervention (10 weeks post-randomisation T2), 8 weeks post-intervention (18 weeks post-randomisation T3), and postnatal follow up (34 weeks post-randomisation T4). Women were paid £10 for their participation at each time-point.
Sample size
In line with guidelines for pilot RCTs, no formal a priori power calculation was conducted (58). A sample size of 30 participants per arm is recommended as providing sufficient data to gain an accurate estimation of the feasibility and acceptability of intervention and trial methods (59), and to provide a reasonable range of estimates of the sample size required for a definitive RCT (60). Thus, we initially aimed to recruit 60 participants in total, although with the subsequent inclusion of a second, more rural, site (Exeter) we were able to recruit 114 participants.
Measures
We collected a range of self-report clinical outcome measures in order to assess the acceptability of these measures and the feasibility of collecting them. The main clinical outcome measure included was for maternal anxiety:
Maternal anxiety was measured using the GAD-7 (55), a 7-item scale measuring symptoms of generalised anxiety disorder. The GAD-7 has excellent internal consistency (Cronbach’s α = .92) and good test-retest reliability (intraclass correlation = 0.83; (55). In this study, Cronbach’s α = .82 at baseline. When used in perinatal populations the GAD-7 has yielded a sensitivity of 61.3% and specificity of 72.7%, using a cut-off score of 13 (56).
We also collected a range of other outcome measures (prospectively described in (49). In this article we assessed means, variability, and effect sizes of measures associated with maternal wellbeing. These included the Edinburgh Postnatal Depression Scale (EPDS; Cronbach’s α = .84), a 10-item self-report scale used to assess antenatal and postnatal depression (57, 61, 62); the 10-item pregnancy-related anxiety scale (PRAQ; Cronbach’s α = .69) (63); and the Dyadic Adjustment Scale (DAS; Cronbach’s α = .90) (64, 65), a 32-item self-report measure of relationship adjustment. Health-related quality of life of the mother was assessed using the EuroQol-5D-3 L measure (66); and health care use was measured with the Adult Service Use Schedule (AD-SUS; (67).
Intervention
The ACORN intervention comprised a manualised group intervention, delivered as three 90-minute group sessions, led by a midwife and psychological provider (e.g., trainee clinical psychologist) who attended a 3-day training in the intervention by HOM. Sessions were audiotaped and reviewed for fidelity at group supervision sessions, led by HOM. Treatment sessions were held at three-week intervals, with the aim of maintaining participant engagement, balancing participant attendance in group sessions with their medical appointments, whilst also providing participants with time to try out practical strategies in-between sessions.
The three group sessions covered key themes determined in collaboration with the research literature and our PPI group. Sessions focussed on perinatal adaptated strategies to managing worry. The primary strategies were centered on problem-solving and managing uncertainty. Managing uncertainty strategies were adapted from Dugas (73) and also included mindfulness-based approaches that were acceptance and compassion-focussed (i.e., loving-kindness towards the fetus). Given the importance of social support during the perinatal period, sessions also included content on communicating about problem-solving with important others. Participants were asked to schedule soothing, self-care related activities each session. See Table 2 for details about the content of each session.
All women in the intervention arm continued to receive their usual care during pregnancy, and had access to the usually available range of interventions for prenatal anxiety and other physical and mental health problems.
Control: Treatment as usual
Women randomised to the control group continued to receive their usual care for prenatal anxiety. There is currently no standard model of care for prenatal anxiety, however midwives are expected to screen for mood and anxiety problems and refer on to care which may include care provided by their GP, specialist mental health midwife, health visitor, or local primary or secondary care mental health team.
Data analysis
Data analysis is primarily descriptive as this is a feasibility study. Participant flow through the study is presented following CONSORT guidelines (Figure 1; (50).
Analyses were conducted with SPSS version 24 and Stata Statistical Software Release 14 (68). First, descriptive data were analysed to calculate: i) percentage of participants meeting eligibility criteria; ii) percentage entering the randomisation phase; iii) the number of sessions completed by those in the treatment arm; iv) percentage completing the outcome measures at post-treatment follow-up. Randomization checks were assessed by between -group comparisons of baseline characteristics on all measures, using χ2 for dichotomous variables and one-way ANOVAs for count and interval data.
Inferential statistics were by intention-to-treat. We used multilevel regression models (STATA ME package) to provide a preliminary test of the potential for the ACORN intervention to have a differential impact on anxiety (GAD-7, PRAQ), depressive symptoms (EPDS), relationship satisfaction (DAS) and quality-of-life (EQ-5D) from baseline through the follow-up periods compared to TAU. STATA ME fits multilevel regression models for a variety of distributions of the response conditional on normally distributed random effects (69). The approach also decomposes the effects for the individual and for the group. Mixed-effects models use all available data. The MIXED procedure was used for all clinical outcomes. All model parameters for continuous outcome measures are presented here as partial standardized effects. Effects for all outcomes measures were adjusted for variance by site.
Effect sizes were standardized effects between conditions from baseline to follow-up, obtained by dividing the unstandardized estimated effects by the pooled standard deviation of the primary outcomes (70).