In total, the 69 articles included in the review included 42 studies and 27 reviews or theoretical conceptual works. Most of the articles described the situation of implementation of the Directive in a given country, mainly in the Netherlands (n = 15), the United States of America (n = 13), Australia (n = 7) and Germany (n = 6). In 47 contributions, barriers or strategies for implementing disease-specific guidelines were described; 22 articles did not focus on a specific disease, but described barriers and strategies in general. A total of 32 articles contain information on barriers and 49 describe strategies for implementing the guidelines. Some articles described both barriers and strategies (n = 12), although they were not always directly related to each other. For more information on the articles included in the qualitative synthesis, see Table 1. The barriers mentioned under personal factors are divided into factors related to physicians` knowledge and attitudes, as these two factors are closely related to behaviour change and are prerequisites for this [22]. With respect to physician knowledge, the main barriers to implementation and compliance are a lack of awareness and familiarity with the guideline and its recommendations [22,33]. In terms of attitudes, the main obstacles are considered to be a lack of agreement, self-efficacy, skills, expectation of results and motivation [22,33,49]. In this context, the derived strategies for the implementation of the guidelines focus mainly on dissemination strategies and pedagogical aspects.
In particular, active learning of experts as thought leaders [14,23,28,71,85] and continuing education [20,28], e.B. through continuing medical education (CME) [82,86], were highlighted as useful tools for improving medical knowledge. When it comes to improving medical attitudes, (individualized) auditing and feedback are considered effective strategies [32,36,43,49]. One intergovernmental organization, the Food and Agriculture Organization of the United Nations (FAO), has 194 member countries, two associate members and one affiliate, the European Union. The employees come from different cultural backgrounds and are experts in the various fields of activity in which FAO is involved. FAO`s human resources capacity enables it to support improved governance, develop, develop and adapt existing tools and guidelines, and provide targeted governance support as a resource to FAO offices at the national and regional levels. FaO is headquartered in Rome, Italy, and is represented in more than 130 countries. The main barriers associated with the factors related to the guidelines are related to the process of developing and creating a guideline.
In particular, the evidence and plausibility of the recommendations are important factors in the development phase. In addition, complexity [27,43,50], provision [57], accessibility [45] and applicability [53] must be taken into account. Therefore, the guidelines should be as short and user-friendly as possible [86] to reduce complexity [27,43,50,53]. Checklists [84] and other tools, such as the inclusion of tablets, smartphones and mobile phones as platforms for issuing guidelines [62] and the implementation of decision support systems [30,57], were identified as appropriate strategies to improve accessibility. The quality of a guideline associated with its use may also depend on the consideration of comorbidity and multimorbidity in its recommendations. Clear intervention objectives must be set [23]. The guidelines are a set of evidence-based recommendations that support care decision-making in specific health systems and resource environments. In the clinical practice of diabetic retinopathy (DR), guidelines provide healthcare professionals with recommendations on the prevention, screening, treatment and/or management of the disease. External factors can also bring several benefits during the policy implementation process. Among the barriers associated with external factors, organizational limitations are of great importance. Therefore, there is a need to improve the organization of care, which can be promoted by the standardization of processes and procedures [87] and the development of protocols [57]. In addition, the healthcare environment must be considered when developing a guideline [46,88] and linkages to quality management [54] can improve compliance.
The obstacle of resource scarcity, such as time constraints and heavy workload [35,55,68], can only be overcome by allowing sufficient time to apply the guidelines in practice [31,69], by defining clear roles in relation to standing orders [31] and by providing financial incentives [42,54]. Multi-professional cooperation with other health professionals can promote the implementation and adherence to the guidelines [20,56]. The local context must also be taken into account to allow local customization of policies [23,50,61]. In addition, local consensus groups can change social norms and thus improve the implementation of the guidelines [85]. There is evidence that multifaceted implementation strategies are the most effective [80,91,92], although Grimshaw et al. [93] argued that multifaceted strategies are not necessarily more effective than individual interventions […].