Although empowerment is one of the core principles of the World Health Organization's approach to health promotion, there are no standards, best practice recommendations, or guidelines for evaluating empowerment within interventions. For the development of effective empowerment promoting interventions, adequate study designs, methods, and indicators for assessing empowerment are essential. In order to better understand which evaluation procedures have been used so far, and which advantages and disadvantages are connected to them, we systematically reviewed empowerment-based health promotion interventions. We included 26 studies, which use a broad variety of quantitative, qualitative, and mixed-methods designs and various data collection methods; qualitative and mixed-methods designs predominated. The quantitative measurement instruments are heterogeneous: Mainly self-designed or modified scales are applied. All studies consider indicators reflecting individual competencies and motivations, whereas indicators capturing the organizational and political components of empowerment are less common. Involving target group members in the development of evaluation procedures and combining different data sources are mentioned as specific steps to improve the quality of data collection. Given the flexible and context-dependent nature of empowerment approaches, the development of a "gold standard" for its evaluation seems unrealistic. However, the analyzed studies can be used to deduce recommendations that may help to conduct high-quality evaluations of empowerment, for example, mixed-methods designs, participation of target groups, and reflective loops within the research team.
Keywords: empowerment; evaluation; health promotion; study design; systematic review.