Measures of fidelity of delivery of, and engagement with, complex, face-to-face health behaviour change interventions: A systematic review of measure quality.

Understanding the effectiveness of complex, face-to-face health behaviour change interventions requires high-quality measures to assess fidelity of delivery and engagement. This systematic review aimed to (1) identify the types of measures used to monitor fidelity of delivery of, and engagement with, complex, face-to-face health behaviour change interventions and (2) describe the reporting of psychometric and implementation qualities.