Patients' self-assessment of essential tremor severity by a validated scale: A useful tool in telemedicine?

Introduction: There are some validated rating scales to assess severity of Essential tremor (ET), the most common cause of action tremor. Clinical evaluation through telematic consultations has been expanding in the last decade. Patients' self-assessment of tremor severity at home could constitute a useful tool in telemedicine. This paper aims to assess intrarater and interrater reliability of ET severity using Fahn-Tolosa Marin Tremor Rating Scale (FTMTRS) for patients' and neurologists' ratings. Material and methods: Patients were instructed on how to perform and rate the FTMTRS tasks. Supervised by neurologists, each patient performed one FTMTRS self-assessment at the hospital, which was rated in a blinded way by two neurologists, and six more self-assessments at home afterwards. Postural, intention and specific-tasks tremor were rated. A cumulative linked mixed model was used to assess intrarater and interrater reliability. Results: A total of 161 self-assessments from 19 patients were analyzed. Intrarater reliability of patients' self-ratings at home showed ICCs between 0.843 and 0.962. Interrater ICCs of neurologists' ratings were also excellent for all tremor types (0.903-0.987). Concordance between neurologists' and patients' assessments showed ICCs ranging from 0.407 to 0.824, with the higher agreement for writing/drawing-related tremor (0.824; CI 95% 0.634-0.989). Conclusions: The rating of ET severity from FTMTRS self-assessments performed by well-trained patients at home could be a suitable clinical measure to assess tremor in non-face-to-face medical consultations. The assessment of tremor during specific tasks could be the most efficient measure for the patient self-assessment at home. These results could be useful in telemedicine.