The McNemar Change Index worked better than the Minimal Detectable Change in demonstrating the change at a single...

To assess the agreement between the Rasch Change Index (RCI), minimal detectable change (MDC), and McNemar Change Index (McCI), three statistics for demonstrating the patient's improvement/deterioration.

The Mini-Balance Evaluation Systems Test (Mini-BESTest (MB)) (a balance scale developed with the Rasch analysis) was administered before and after rehabilitation to 315 neurological patients. The MB RCI was chosen as the criterion standard for detecting the patient's improvement. Positive likelihood ratios and negative likelihood ratios (PLRs and NLRs, respectively) were used to evaluate the MDC and McCI accuracy in identifying the patient's improvement. Three different MB MDCs were assessed.

One-hundred patients improved their MB in accordance with the RCI. All three MDCs and the McCI were solid in ruling out the patient's improvement (NLR <0.2). The McCI and the largest MDC were also good in detecting the patient's improvement (PLR>5), whereas the smaller MDCs were not. Of the four indices, McCI was the most robust in case of missing items.

A patient stable in accordance with the MDCs or McCI is actually stable as per the criterion standard. To be reasonably sure that the patient is actually improved, larger MDC values or the McCI should be preferred, and the McCI is preferable if there are missing items.