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Table 2 Arguments for Fidelity and Adaptation

From: The Value Equation: Three complementary propositions for reconciling fidelity and adaptation in evidence-based practice implementation

ArgumentFidelity …Adaptation …
1… is vital for drawing valid conclusions by:… improves intervention–context fit by:
- increasing internal validity by the transparent and adherent use of EBIs [35]
- separating implementation failure from theory failure, i.e., distinguishing between lack of effects due to insufficient implementation from lack of effects of an ineffective intervention [47]
- avoiding type-III errors: concluding that an intervention is not effective when it actually was poorly implemented [48]
- ensuring that EBIs can be implemented and used in/for systems, organizations, providers, or patients that is different than the one in which the EBI was originally tested [49]
- increasing the acceptability, feasibility, and applicability of an EBI to a given context [29]
- increasing practical and/or value fit (philosophical and cultural) [12], e.g., creating fit with practical circumstances by changing from individual treatment to group format to align with funding contract [50]
2… makes accumulation of knowledge possible by:… balances different outcomes by:
- making replication possible by ensuring the intervention remains the same across studies, thereby distinguishing between random and robust results [35, 51]
- allowing results from multiple studies to be synthesised in systematic reviews and meta-analyses
- focusing on a broader spectrum of objectives, e.g., not only the specific clinical outcome an EBIs is evaluated against (e.g., symptom reduction, improved functioning) but also outcomes on other levels (patient, provider, organization and system) such as reach, relevance, costs [29, 49, 52]
- focusing on optimizing benefits over time rather than focusing on sustained delivery (i.e., sustainment) [14, 28, 53, 54]
3... assures EBI effectiveness by:...  assures EBI effectiveness by:
- relying on studies, across different types of interventions and settings, showing that high fidelity can improve outcomes (e.g., [27, 37, 55,56,57,58] (at least in comparison to drift)- relying on studies, across different types of interventions and settings, showing that adaptations can improve outcomes, e.g., [20, 59] (at least when there is a large variation in client and provider characteristics)
4... provides transparency and confidence by:... is necessary to address multiple diagnoses by:
- ensuring that users, patients and their families, care providers, and funders (health systems, governments, insurers, and foundations) gets what they are promised [47, 60]:
 ... that patients know that the EBI offered is also the EBI delivered, facilitating informed choices
 ... that subsequent providers can deliver appropriate care; trusting that the treatment as documented in clinical records is also the treatment delivered
 ... that funders get what they are paying for
 ... that systems allow fair comparison between organizations in a competitive market, and fair benchmarking of treatment outcomes
- acknowledging that comorbidity is the rule rather than the exception in clinical practice, and that most EBIs have only been indicated (shown to be effective) for a very limited group of patients, primarily without comorbidities [61]
- allowing “indication shift” to be able to use EBIs for groups for which evidence is lacking
5...  provides equal care and reduces disparities by:... optimise the benefit for each patient by:
- decreasing unwanted variation between providers, organizations, geographical regions, and different target groups or individuals, e.g., between men and women [60]
- ensuring that decisions about adoption and use are made systematically, reducing the risk of gender and cultural biases
- translating mean effects into what is best for each individual in the group [62]
- taking individual patient variability into account by detecting the individuals that are likely to improve less (i.e., the tails of the distribution of effects), consistent with the personalized medicine movement [63]