Matters arising: a critique of "Nuancing the continuum from ideal to real-world implementation" by Eldh et al. 2025.

This critique responds to Eldh et al.'s (Implement Sci Commun 6:113, 2025) commentary on Nilsen et al.'s proposal to distinguish between implementation efficacy and effectiveness along an ideal-to-real-world continuum. While acknowledging the constructive intent of Eldh et al.'s reflections, we clarify that our framework was never intended as a simplistic, one-dimensional model but as a pragmatic heuristic to enhance design transparency. Eldh et al.'s proposed two-axis alternative is conceptually overlapping, as both axes reflect contextual variation rather than independent constructs. Our adaptation of the PRECIS framework - long validated in clinical and health services research - already incorporates multidimensional nuance through distinct domains. We emphasize that the "ideal" end of the continuum denotes highly supported conditions, not normative perfection. Moreover, the proposed "Implementation PRECIS" tool is intended to stimulate integration of contextual transparency and economic evaluation within implementation research. While we concur with Eldh et al.'s emphasis on facilitation, co-production, and contextual complexity, their critique ultimately reinforces our core premise: that explicitly positioning studies along an efficacy-effectiveness spectrum strengthens interpretability, transparency, and real-world relevance in implementation science.