Translation and adaptation of a dysarthria assessment tool to be used in the Sri Lankan clinical context

Abstract

Background: Dysarthria is one of the commonest communication disorders that arise due to neuromuscular damage. Diagnosing dysarthria requires careful assessments. In the absence of a formal dysarthria assessment tool in the Sri Lankan (SL) clinical context, the translated and adapted Sinhala Language Newcastle Dysarthria Assessment Tool (SLN-DAT) was validated using a normative sample. Methods: This research study was conducted in three phases related to 3 objectives using a mixed methodology: (I) Identification of the relevant tool amongst FDA, DP and N-DAT to be adapted and translated to the SL context using views of 20 Speech and Language Therapists (SLTs) and 20 undergraduate final year students; (II) Initial translation and adaptation of assessment tool into Sinhala language based on WHO tool translation guidelines; (III) Face, content and concurrent validity of the tool using 10 subject experts and 50 normative samples of five age ranges (20-40,40–60,60–70,70–80 and 80+). Internal consistency and intra-rater agreement for the tool tasks were analysed by the subject specialists and concurrent validity were assessed comparing the scores of Dysarthria Profile (DP) and SLN-DAT tool. Data was analyzed using SPSS (Statistical Package for Social Sciences) statistical software and the thematic analysis was used for the qualitative part of the study. Results: N-DAT was selected as the most voted (SLTs=58% & students=55%), and relevant dysarthria assessment tool to be translated and adapted to the SL context. At the end of phase II, the assessment tool contained all related sections of the original N-DAT in Sinhala, which was adapted to suite to SL context. Overall, the SLN-DAT has the same conceptual meaning, semantics, idiomatic and score equivalences as the original version, yet SLT-DAT had one additional section related to ICF model. Statistical analysis showed higher agreement among graders (missing data 0%), including high internal consistency for tool items (Cronbach’s α = 0.8) including the new sections. Performance of the normative sample exhibited a predicted variation among age and tool performance with negative correlation for articulation r = -.32 (p<0.05), respiration r = -.70 (p<0.01), phonation voice r = -.33 (p<0.05), phonation pitch r = -.40 (p<0.01) and DDK rates r = -.33 (p<0.01). The concurrent validity of the SLN-DAT was very high for all subsystems. Each subsystem had higher ICC values ranging between r = 1.0 – 0.7 (p<0.01). Conclusion: The translated, adapted and validated formal dysarthria assessment tool; Sinhala Language Newcastle Dysarthria Assessment Tool (SLN-DAT) had higher face validity, higher internal consistently with items and satisfactory concurrent validity. Therefore, the SLN-DAT could be recommended to the SL context after it was validated among the dysarthria population, which will enable to identify dysarthria reliability in the Sri Lankan clinical context.