A continuity of care programme for women at risk of preterm birth in the UK: Process evaluation of a hybrid randomised controlled pilot trial

BACKGROUND: The development and evaluation of specific maternity care packages designed to address preterm birth remains a public health priority. We aim to evaluate the implementation, context, and potential mechanisms of action, of a new care pathway that combined midwifery continuity of care with a specialist obstetric clinic for women at risk of preterm birth (POPPIE) in London (UK). METHODS: We did a multiphase mixed method triangulation evaluation nested within a hybrid type 2, randomised controlled trial in London (United Kingdom). Pregnant women with identified risk factors for preterm birth were eligible for trial participation and randomly assigned (1:1) to either midwifery continuity of care linked to a specialist obstetric clinic (POPPIE group) or standard maternity care. The primary outcome was a composite of appropriate and timely interventions for the prevention and/or management of preterm labour and birth, analysed according to intention to treat. Clinical and process outcome data were abstracted from medical records and electronic data systems, and coded by study team members, who were masked to study group allocation. Implementation data were collected from meeting records and key documents, postnatal surveys (n = 164), semi-structured interviews with women (n = 30), healthcare providers and stakeholders (n = 24) pre-, mid and post implementation. Qualitative and quantitative data from meeting records and key documents were examined narratively. Qualitative data from interviews were analysed using three thematic frameworks: Proctor’s (for implementation outcomes: appropriateness, adoption, feasibility, acceptability, fidelity, penetration, sustainability), the Consolidated Framework for Implementation Research (for determinants of implementation), and published program theories of continuity models (for potential mechanisms). Data triangulation followed a convergent parallel and pragmatic approach which brought quantitative and qualitative data together at the interpretation stage. We averaged individual implementation measures across all domains to give a single composite implementation strength score which was compared to the primary outcome. RESULTS: Between May 9, 2017, and Sep 30, 2018, 553 women were assessed for eligibility and 334 were enrolled with less than 6% of loss to follow up (169 were assigned to the POPPIE group; 165 were to the standard group). There was no difference in the primary outcome (POPPIE group 83·3% versus standard group 84·7%; risk ratio 0·98 [95% CI 0·90 to 1·08]). Appropriateness and adoption: The introduction of the POPPIE model was perceived as a positive fundamental change for local maternity services. Partnership working and additional funding were crucial for adoption. Fidelity: More than 75% of antenatal and postnatal visits were provided by a named or partner midwife, and a POPPIE midwife was present in more than 80% of births. Acceptability: Nearly 98% of women who responded to the postnatal survey were very satisfied with POPPIE model. Quantitative fidelity and acceptability results were supported by the qualitative findings. Penetration and sustainability: Despite delays (likely associated with lack of existing continuity models at the hospital), the model was embedded within established services and a joint decision was made to sustain and adapt the model after the trial (strongly facilitated by national maternal policy on continuity pathways). Potential mechanisms of impact identified included e.g. access to care, advocacy and perceptions of safety and trust. There was no association between implementation measures and the primary outcome. CONCLUSIONS: The POPPIE model of care was a feasible and acceptable model of care that was implemented with high fidelity and sustained in maternity services. Larger powered trials are feasible and needed in other settings, to evaluate the impact and implementation of continuity programmes in other communities affected by preterm birth and women who experience social disadvantage and vulnerability. TRIAL REGISTRATION: UKCRN Portfolio Database (prospectively registered, 24 April 2017): 31951. ISRCTN registry (retrospectively registered, 21 August 2017): ISRCTN37733900.