Irregular assessment times in pragmatic randomized clinical trials.

Deviation from protocolized assessment times is commonplace in pragmatic randomized clinical trials. Working with a stakeholder advisory board for a Patient-Centered Outcomes Research Institute®-funded project on statistical methods for handling potential biases introduced by irregular assessment times, we identified reasons for off-schedule or missed assessments. We used the Consolidated Framework for Implementation Research 2.0 to organize our findings. We conjectured that timely completion of outcome assessments is a function of multiple determinants, only some related to participants' health status. We identified potential determinants that can be modified during the protocol design stage and can be reassessed and mitigated during trial implementation stage. Research to more formally evaluate our findings is warranted as well as studies to evaluate multi-level strategies that reduce off-schedule or missed assessments.