Validation study of the Spanish version of the Fahn-Tolosa-Marin scale for essential tremor
Correspondencia: Dra. María Victoria Castrillo Fraile. Servicio de Rehabilitación. Hospital Universitario de Burgos. Avda. Islas Baleares, 3. E-09006 Burgos.
E-mail: vcastrillof@saludcastillayleon.es
Introduction: The Fahn-Tolosa-Marin (FTM) tremor rating scale has been widely used in clinics for the estimation of tremor severity. However, a Spanish language version of this scale has still not been formally validated. Aim: To provide support to the validity and reliability of this version of FTM Scale. Patients and methods: A cross-sectional study was conducted on essential tremor patients. Severity was rated using the FTM scale. Upper limb disability was evaluated by terms of Disabilities of the Arm, Shoulder and Hand Scale (DASH), and to health-related quality of life using the Short Form-36 Health Survey (SF-36). Statistical analysis included sample description, reliability (Cronbach's alpha), convergent validity, and discrimination capacity tests (ROC curves). Results: Forty patients with essential tremor (22 women, 18 men) were included, with a mean age of 65.8 ± 14.7 years (range: 21-90 years). Internal consistency of the FTM was high: Cronbach's alpha: 0,90 (subscale A: 0.85; subscale B: 0.91; subscale C: 0.77), and the floor and ceiling effects were negligible. The FTM (subscale C) showed high correlations with DASH, and acceptable diagnostic capacity, with an area under the curve of 0.86 (95% CI: 0.67-1.00), sensitivity 78% and specificity 75% for a cut-off score > 5.5. Conclusion: The Spanish version of FTM the rating scale is a reliable and valid tool to evaluate disability in patients with essential tremor, and a suitable instrument for use in medical research, as well as in clinical practice.
Objetivo Analizar la validez y la fiabilidad de la versión en castellano de la escala FTM.
Pacientes y métodos Estudio observacional transversal en pacientes diagnosticados de temblor esencial. Se evaluó la gravedad del temblor con la escala FTM; la discapacidad en el miembro superior, con la escala Disabilities of the Arm, Shoulder and Hand (DASH), y la calidad de vida relacionada con la salud, con el cuestionario Short Form-36 Health Survey (SF-36). El análisis estadístico incluyó descripción de la muestra, fiabilidad (alfa de Cronbach), validez convergente y capacidad discriminatoria (curvas ROC).
Resultados Se incluyó a 40 pacientes (22 mujeres y 18 hombres con temblor esencial), con una edad media de 65,8 ± 14,7 años (rango: 21-90 años). La fiabilidad de la FTM fue alta, con un alfa de Cronbach de 0,90 (subescala A: 0,85; subescala B: 0,91; subescala C: 0,77). Para evaluar la discapacidad originada por el temblor esencial, la validez convergente entre las escalas DAHS y FTM (subescala C) fue adecuada, con una capacidad diagnóstica aceptable: área bajo la curva de 0,86 (intervalo de confianza al 95%: 0,67-1,00), sensibilidad del 78% y especificidad del 75%, para un punto de corte mayor de 5,5.
Conclusión La escala FTM es un instrumento fiable, válido y preciso para la valoración del temblor esencial en la población española adulta.
