Which statement defines the CAR deficit threshold?

Which statement defines the CAR deficit threshold?

• A. CAR deficit is defined when CAR < 0.90
• B. CAR deficit is defined when CAR < 0.95
• C. CAR deficit is defined when CAR < 1.00
• D. CAR deficit is defined when CAR < 0.85

Answer: (B)

The idea behind a CAR deficit threshold is to flag impairment only when the CAR value falls below a reasonable cutoff, reflecting a response that is notably worse than predicted but still accounting for normal variability. Setting the threshold at 0.95 means that if the CAR is at or above 95% of the predicted/normal level, function is considered adequate; once it drops below 0.95, a deficit is indicated. This strikes a balance between catching true deficits and avoiding false positives from small measurement fluctuations. If the threshold were higher, like 1.00, even tiny deviations would be labeled as deficits, which isn’t practical. If it were much lower, like 0.85, milder deficits could be missed. Values around 0.95 are chosen because they reflect a meaningful drop without overreacting to normal variability. So, the statement defining the CAR deficit is that CAR is considered deficient when CAR < 0.95.

The idea behind a CAR deficit threshold is to flag impairment only when the CAR value falls below a reasonable cutoff, reflecting a response that is notably worse than predicted but still accounting for normal variability. Setting the threshold at 0.95 means that if the CAR is at or above 95% of the predicted/normal level, function is considered adequate; once it drops below 0.95, a deficit is indicated. This strikes a balance between catching true deficits and avoiding false positives from small measurement fluctuations.

If the threshold were higher, like 1.00, even tiny deviations would be labeled as deficits, which isn’t practical. If it were much lower, like 0.85, milder deficits could be missed. Values around 0.95 are chosen because they reflect a meaningful drop without overreacting to normal variability.

So, the statement defining the CAR deficit is that CAR is considered deficient when CAR < 0.95.