Fidelity scale: From black box to holy grail

Fidelity scales are indispensable in the pursuit of evidence-based mental healthcare. Without fidelity checks, treatment remains a mysterious black box. The aim of this article is to comment on the studies in this special section, and to discuss some general issues with regard to fidelity assessment. Despite all of their supposed benefits, resistance to fidelity scales persists among mental health practitioners. One way to overcome this resistance is to conduct fidelity assessments in the context of a well-guided learning community. The predictive validity of fidelity scales is considered the single most valuable attribute of these instruments. Research on predictive validity requires large sample sizes, which is difficult to achieve. It should nevertheless not prevent us from rigorously searching for this Holy Grail of fidelity assessment. In addition, fidelity assessment should be placed in a broader perspective. The quality of care for people with severe mental illness cannot be assessed conclusively according to the extent to which separate interventions have been applied with good fidelity. These individuals need access to high-quality treatment and support systems within the community, which can enable them to live their lives as valued citizens. In conclusion, fidelity assessment, both at the level of interventions and systems, contributes to a highly desirable transparency in practice variations within the field of mental healthcare.