A proposal for application and scoring of the Clock Drawing Test in Alzheimer's disease
Correspondencia: Dr. Jesús Cacho Gutiérrez. Hospital Clínico Universitario de Salamanca. Sección de Neurología. Paseo de San Vicente 58-182. E-37007 Salamanca.
Email: jcachog@meditex.es
Introduction: The Clock Drawing Test (CDT) has been used in recent years as a simple neuropsychological instrument to assess cognitive deterioration associated with dementia, even though uniform operative criteria with respect to its application and scoring have not been established.
Objective: To present application normatives and establish the most relevant psychometric criteria of the CDT in a sample of healthy subjects (HS) and patients with Alzheimer's disease (AD).
Patients and methods: 56 patients were selected of which 35 were female and 21 were male. The patients' mean age was 72.7 with a standard deviation of 7.64. All of whom where probable AD patients according to the NINCDS-ADRDA criteria at stage 1 CDR. The group of HS was made up of 56 control subjects (34 female, 22 male) with a mean age of 72.14 and a standard deviation of 7.2. The CDT was applied in both its command (COM) and copy (COP) experimental conditions.
Results: The main psychometric parameters analysed in the studied series showed the following values: internal consistency (Cronbach's alpha coefficient 0.9029); cut off point CT COM 6 with 92.80, sensitivity; false negatives (FN) 7.2 with a specificity rating 93.48; false positive (FP) 6.52 with 93.16 efficacy; cut off point CT COP 8 with 73.11 sensitivity; FN 26.89 with 90.58 specificity; FP 9.42 with 82.49 efficacy.
Conclusion: The CDT can be used to discriminate between HS and those in the initial stages of AD in the given sample using the established application and scoring criteria.
Objetivos Presentar una normativa de aplicación y puntuación, y establecer los criterios psicométricos más relevantes del TR en una muestra de sujetos controles (SC) y pacientes con enfermedad de Alzheimer (EA).
Pacientes y métodos Hemos seleccionado a 56 pacientes, 35 mujeres y 21 varones, con EA probable (criterios NINCDS-ADRDA) y estadio 1 (criterios CDR), con una media de edad de 72,7 y una DT de 7,64. El grupo SC está constituido por 56 sujetos control, 34 mujeres y 22 varones, edad media de 72,14 y DT 7,2. Se ha utilizado el TR en dos condiciones experimentales: TR ‘a la orden’ (TRO) y TR ‘a la copia’ (TRC).
Resultados Los principales parámetros psicométricos analizados en la serie estudiada muestran los siguientes valores: consistencia interna (coeficiente alfa de Cronbach 0,9029), punto de corte TRO 6 con sensibilidad 92,80, falsos negativos (FN) 7,2, especificidad 93,48, falsos positivos (FP) 6,52, eficacia: 93,16; punto de corte TRC 8 con sensibilidad 73,11, FN 26,89, especificidad 90,58, FP 9,42, eficacia: 82,49.
Conclusiones El TR permite discriminar entre sujetos sin deterioro cognitivo y pacientes en estadio incipiente de EA con los criterios de aplicación y puntuación utilizados
