gms | German Medical Science

Background: Mother’s own milk (MOM) is critical for every newborn, especially for vulnerable newborns, such as preterm infants with a very low birth weight (VLBW) of less than 1,500 grams, in order to reduce mortality and promote infant development. Currently, there is a lack of structured lactation and breastfeeding support, which is particularly important for VLBW infants’ mothers, as breast milk production might be delayed or impaired. When MOM is not available, human donor milk (HDM) is the preferred alternative. The Neo-MILK project therefore aims to improve access to MOM or, if MOM is not available, HDM for VLBW infants in German level I neonatal intensive care units (NICUs) by implementing a structured lactation and breastfeeding programme and establishing human donor milk banks. To develop an in-depth understanding of how specific components of the complex intervention work, for whom, and under what circumstances, we are conducting a realist process evaluation. The theory-driven realist methodology is a relatively new approach to evaluating complex interventions and aims to uncover the underlying mechanisms of interventions that are responsible for a change in outcomes.

Objective: To present the methodology of a realist process evaluation of a complex intervention in the context of neonatal intensive care units.

Methods: Neo-MILK is a hybrid type 1 effectiveness-implementation cluster-randomised, controlled trial using a stepped-wedge design, which is conducted over a total period of 26 months in 15 level I NICUs across Germany. The study consists of a summative and a formative evaluation including a process evaluation. Some parts of our process evaluation are in line with realist principles, as we aim to refine and consolidate the initial programme theory (ITP). The ITP is based on qualitative interviews with project members who developed the complex intervention and a realist review of breastfeeding interventions in the NICU context. After analysing all the data, context-mechanism-outcome (CMO) configurations are described. In a next step, we refine these CMO configurations with insights from interviews with NICU staff who are responsible for or operationally involved in the implementation of the Neo-MILK intervention. To test the theory, we conduct interviews with mothers of VLBW infants and use explorative analyses of quantitative study data.

Implication for research and/or (healthcare) practice: In order to gain a comprehensive understanding of how, for whom, and under what circumstances a complex intervention works, it is essential to consider the involvement of multiple stakeholders (e.g., intervention developers, health care providers and recipients) in the evaluation. For future researchers to ground their studies in theory, programme theories should be developed progressively through empirical research, theory building and testing. Testing hypotheses derived from the CMO configurations using empirical methods could be a further step towards more robust theories. For health care providers, programme theory can serve as a valuable tool to help develop organisational policies and guidelines, or be used as a basis for quality management.

Funding: Innovationsfonds/Versorgungsforschung; Project name: Neo-MILK: Strukturelle Stillförderung und Aufbau von Humanmilchbanken an neonatologischen Zentren; Grant number: 01NVF19027