The Application of Minimal Clinically Important Differences in Palliative Research: Interpretation of Results of a Systematic Review

Context: Interpreting clinical meaningfulness of patient reported outcomes (PROs) in palliative care research is key in evidence-based practice. Minimal clinically important differences (MCIDs) can help interpret whether changes in PROs are meaningful to patients. Objective: To examine use of MCIDs in a recent systematic review on integrating palliative care into ambulatory care for U.S. adults with noncancer serious chronic illness and their effect on interpretation of key PROs. Methods: Paired investigators abstracted MCIDs for each PRO in the systematic review from PubMed, tool specific websites, and Google Scholar. Investigators compared findings and resolved differences through consensus. MCIDs were interpreted alongside results from meta-analyses or individual studies to draw conclusions on effectiveness of interventions. Results: MCIDs could be identified for 10 of 23 instruments affecting seven of nine outcomes. The most notable effect was for depressive symptoms, where three trials reported statistically significant differences that were not clinically meaningful based on available MCIDs. Although differences in statistical significance and MCIDs were noted for other outcomes, they were accounted for in meta-analyses or affected a minimal number of studies within the outcome category. Conclusions: Incorporating MCIDs affected the interpretation of almost all PROs in the systematic review. MCIDs are important measures of clinical meaningfulness for the interpretation of palliative care research involving PROs. Researchers should consider using instruments with well-established MCIDs and incorporate MCIDs, when available, in study design and interpretation.