Fidelity and moderating factors in complex interventions: a case study of a continuum of care program for frail elderly people in health and social care

The intervention was a systematization of the collaboration between a nurse with geriatric expertise situated at the emergency department, the hospital ward staff, and a multi-professional team with a case manager in the municipal care services for older people. Implementation was evaluated between September 2008 and May 2010 with observations of work practices, stakeholder interviews, and document analysis according to a modified version of The Conceptual Framework for Implementation Fidelity.A total of 16 of the 18 intervention components were to a great extent delivered as planned, while some new components were added to the model. No changes in the frequency or duration of the 18 components were observed, but the dose of the added components varied over time. Changes in fidelity were caused in a complex, interrelated fashion by all the moderating factors in the framework, i.e., context, staff and participant responsiveness, facilitation, recruitment, and complexity.The Conceptual Framework for Implementation Fidelity was empirically useful and included comprehensive measures of factors affecting fidelity. Future studies should focus on developing the framework with regard to how to investigate relationships between the moderating factors and fidelity over time.ClinicalTrials.gov, NCT01260493.Intervention research has seldom systematically documented how different intervention components have been implemented in practice [1]. Analysis of the implementation process and its fidelity is important in order to understand what specific reasons caused an intervention to succeed or fail [2-6]. This is especially relevant for complex interventions that consist of several active ingredients [7,8]. Otherwise, there is a risk of evaluating effects of a program that have been described but not fully implemented [8].Implementation fidelity is often defined as the degree to which a particular program follows an original program model, i.e., the model that was intended to be use