To our knowledge, this is the first study that explores factors of importance for sustainability of a multisectoral child health promotion programme in a Swedish context. The programme was described as sustainable at most sites, except in child health care. The perception of facilitators, barriers, and requirements were largely shared across sectors. Facilitators included being actively involved in intervention development and small-scale testing, personal values corresponding to programme intentions, regular meetings, working close with collaborators, using manuals, and a clear programme branding. Existing or potential barriers included insufficient managerial involvement and support and perceived constraints regarding time and resources. In dental health care, barriers also included conflicting incentives for performance. Many facilitators and barriers identified by participants also reflected their perceptions of more general and forthcoming requirements for programme sustainability. From our point of view, this strengthens the importance of these factors.
The theoretical framework proposed by Grol and Wensing  was found to be feasible in structuring results of this study, findings that support its usefulness as a multilevel approach to examine factors of importance for sustainability of innovations. This framework has been used in previous studies to identify facilitators and barriers for change [36, 37]. However, our results contribute to extend the framework by also including the level of the development process, as several facilitating factors were found at this level. Other theoretical frameworks (for example, as proposed by Cabana et al.) might also have been applicable .
Professionals' participation early in the process of programme development and the use of small-scale testing were described as strongly contributing to programme sustainability. During that process, interventions became context adapted and a sense of ownership of the programme was fostered on behalf of the professionals. These results are consistent with previous research findings regarding positive aspects of involving front-line professionals in intervention development [19, 39–41]. The risk of low awareness and limited practical use of guidelines that mainly were developed at managerial levels has previously been recognized .
The difficulties of sustaining long-term compliance rates are well known [6, 20]. Therefore, the relatively high level of perceived programme sustainability among professionals in this study is an interesting finding, especially since well-recognized barriers in terms of insufficient support from managers and peers as well as understaffing and time constraints were reported from all sectors . These factors mainly affected professionals in child health care, and lack of sustainability in this sector might be attributable to a more comprehensive intervention package and a more pressed work situation. The relatively high age of the involved child health nurses could be a contributing factor, as older and experienced professionals tend to use guidelines to a lesser extent compared to their younger and less experienced peers .
Most participants viewed the use of manuals, including protocols and questionnaires, as highly valuable in achieving sustainability by facilitating a standardized way of working and by serving as supporting tools when raising sensitive questions. The use of growth charts has previously shown to facilitate raising issues about overweight in child health care , and structured protocols for screening has shown to raise awareness and improve documentation of child abuse among emergency department staff . However, previous qualitative research regarding the role of manuals as tools in similar health promotion initiatives is scarce and further studies are needed.
The perceived attributes of the innovation, including relative advantage, compatibility, complexity, trialability, and observability can, according to Rogers, explain between 49% to 87% of the variance in the rate of adoption . Furthermore, interventions that can easily be tried out in practice and that do not need additional resources are more likely to be implemented . Professionals' training has also been found to be a crucial factor in achieving sustainability of health education programmes in schools . These factors were also facilitated because of the chosen strategy to involve front-line professionals in programme development.
However, there are conflicting messages concerning whether guidelines developed by involved professionals themselves are used more often or not . There is also criticism of the 'participation model' concerning the risk of not introducing the best care possible and the risk of not paying attention to structural factors that are important for successful implementation . Some factors were found to serve as both facilitators and barriers for sustainability. One example is the experience of being motivated by involvement, but at the same time facing lack of managerial support when given authority to participate in programme development. This phenomenon has previously been examined [47, 48]. In this study, the advantages of the participation model were challenged by the perceived difficulties at the organisational level. Results indicate that there might be risks for less programme sustainability if managerial levels are not involved and if an organizational structure for continuing support and development is not sustained [49, 50]. Furthermore, conflicting incentives for performance, as described by professionals in dental health care, might also pose a threat to long-term programme sustainability; clearly, these conflicts should be taken into account. Hence, this study highlights the importance of planning for sustainability at an early stage in programme development  and of analysing both target contexts and target groups before intervention and implementation designs are set [52–54].
Multidisciplinary collaboration is often aimed for in health services, but it is rarely achieved with ease. Our results indicate that teamwork can be enhanced and synergies created by regular meetings and by sharing premises or having geographical proximity. This might be important to consider for those who have mandate to decide on the organization of services for expectant parents and young children that depend on multisectoral collaboration. These results also appear consistent with previous results regarding facilitators and barriers to such collaboration . Stability in the work force from programme initiation until the time when the study was undertaken likely contributed to programme sustainability. Otherwise, high rates of professionals' turnover can undermine existing collaboration as key persons leave their positions [56, 57].
The role of the programme's brand name in facilitating for professionals to raise uncomfortable questions with clients was a somewhat unexpected finding. Thus, not only is a brand name important in relation to the adoption of health behaviour of individuals . The right branding might also serve as a facilitator for clarifying the programme's mission and goal, encouraging behavioural change among professionals working in the field of health promotion. Interestingly, this seems to be an often overlooked factor in previous discussions of facilitating factors for behavioural change among this diversity of professionals, even though the importance of communicating visions and goals has been recognised.
A qualitative approach with inductive coding and categorizing [34, 53] was considered appropriate since studies of barriers and facilitators in similar contexts as well as implementation studies involving other professionals than physicians are sparse . Rich data were obtained as all professionals in the pilot areas consented to take part in the study [59, 60]. The importance of having an open-ended approach was confirmed since an existing framework used for organizing findings was expanded. In addition, the similarity of issues raised by participants regardless of profession indicates that our findings might also be transferable to other professions and settings. As the study covered the whole eligible population, we decided to specify some quantities in the results section. However, the quantification of data should be interpreted with caution, and our results cannot be considered as exhausting the area of barriers and facilitators due to their sensitivity to the intervention, target group, and context. A limitation of this study is that it reflects the views of the programme's front-line professionals. Perspectives of people at the managerial levels and of the receivers of interventions (i.e., expectant parents and parents) would add value and provide a more comprehensive picture of important factors of sustainability. A more objective assessment of sustainability is also warranted. Furthermore, the study reflects the perceptions of female participants of similar age. Nevertheless, the proportion of women in this study mirrors the general female predominance in these sectors in Sweden. A re-organization into family centres during the start-up phase of the Salut Programme might have influenced our results as it led to closer proximity and opportunities for collaboration between maternal health care, child health care, open pre-school, and social services. Due to this, it might be possible that the importance of having collaborators nearby were raised to a greater extent. Finally, because of the recent launch of the programme interventions, their effectiveness has not yet been evaluated or reported, something that otherwise would have strengthened this study.