Interpreting Patient Reported Outcome Results: Is One MCID Value Really Enough?
Benjamin F Sandberg, MD1; Dylan L McCreary, BA2; Deborah Bohn, MD3; Brian P Cunningham, MD2; (1)University of Minnesota, Minneapolis, MN, (2)Regions Hospital, St. Paul, MN, (3)Orthopaedics, Park Nicollet Health Services/Tria Orthopaedic Center, Minneapolis, MN
Introduction: Patient reported outcomes (PROs) are the gold standard for reporting clinical outcomes in research and cost-effectiveness analysis. A crucial component of interpreting PROs is the minimum clinically important difference (MCID). Prior studies have suggested many factors including the method used and data analyzed substantially affect the MCID values calculated. The MCID for the Patient Rated Wrist Evaluation (PRWE) has yet to be rigorously defined. The purpose of this study was to determine if a single value for the MCID of the PRWE in distal radius fracture (DRF) patients could be reported.
Methods: From 2014-2016, patients with a DRF treated at a single Level I trauma center were identified from a prospective registry. Inclusion criteria were isolated DRF, age older than 18 years, and complete PRWE and anchor questions. The MCID was calculated using an anchor based method with both an overall health (OHA) and emotional health (EHA) anchoring question. The MCID was determined using the anchor and distribution method for the relevant combinations of follow up duration, injury, and treatment method.
Results: 197 patients met inclusion criteria. Average age was 57 ± 17 and 149 patients (76%) were female. A total of 112 patients (57%) were treated operatively. There were 100 patients sustaining AO/OTA classification 23A fractures (51%), 30 patients with 23B (15%), and 62 patients with 23C (31 %). Combining all MCID values the average MCID was 26.0±15.8, range 5.5 to 63.7. The MCID values calculated differed significantly when evaluated with different methods or at different time points (Table 1), with different injuries (Table 2) or with different treatments (Table 3)
Conclusion: The MCID was heavily influenced by assessment time points, analytical method, treatment modality, and fracture classification. This result stands in distinction from the presentation of the MCID as a single value for an individual instrument or disease state and suggests that an anchor question should be used in clinical trials to establish the MCID in the context of each study.
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