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.
Title: Estudio de validacion de la version española de la escala Fahn-Tolosa-Marin para el temblor esencial.
Introduccion. Hasta ahora no existe una validacion formal de la version española de la escala Fahn-Tolosa-Marin (FTM), usada ampliamente para valorar la gravedad del temblor. Objetivo. Analizar la validez y la fiabilidad de la version en castellano de la escala FTM. Pacientes y metodos. Estudio observacional transversal en pacientes diagnosticados de temblor esencial. Se evaluo 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 analisis estadistico incluyo descripcion de la muestra, fiabilidad (alfa de Cronbach), validez convergente y capacidad discriminatoria (curvas ROC). Resultados. Se incluyo 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 diagnostica aceptable: area 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. Conclusion. La escala FTM es un instrumento fiable, valido y preciso para la valoracion del temblor esencial en la poblacion española adulta.