Equivalency and practice effects of alternative versions of the Edinburgh Cognitive and Behavioral ALS Screen (ECAS).

To examine the equivalency of ECAS versions A, B, and C in an Irish cohort, and to examine potential practice effects, 236 healthy controls were recruited through the Irish ALS control database. One hundred and seventy-six (176) controls completed ECAS version A, B, or C. Separately, 60 controls completed all three versions (A-B-C), consecutively, four months apart. TOST analysis found that ECAS A was equivalent to ECAS B and C. ECAS B and C were not statistically equivalent, however the difference between them was minimal. Participants showed improvement in ECAS performance over time, indicative of practice effects. Significant improvement was observed from time 1 to 2, but not from time 2 to 3. We propose Irish specific reliable change index (RCI) scores that take into consideration practice effects and measurement error. These thresholds will help quantify clinically meaningful cognitive decline in ALS patients, leading to improved quality of care.