A diagnostic test for apraxia in stroke patients: internal consistency and diagnostic value

The internal consistency and the diagnostic value of a test for apraxia in patients having had a stroke are presented. Results indicate that the items of the test form a strong and consistent scale: Cronbach's alpha as well as the results of a Mokken scale analysis present good reliability and good scalability. The diagnostic value of the test was determined by comparison of test results in three groups of patients: 44 stroke patients with apraxia (patients), 35 stroke patients without apraxia (patient controls), and 50 healthy nursing home residents with no history of stroke (normal controls). The diagnostic value is expressed by means of the sensitivity and specificity and the predictive value of the test. In addition, Receiver Operator Characteristics (ROC) curves are presented. The sensitivity and specificity of the apraxia test appear to be good: all values are higher than 80%. The test also has high predictive value. The ROC curves illustrate that the test is sufficiently discriminative to allow a differentiation between persons with apraxia and persons without apraxia.