A Psychometric Evaluation of the Threadgold Communication Tool for Persons with Dementia

BACKGROUND The objective of this study was to investigate the psychometric properties of the Threadgold Communication Tool (TCT). METHOD Internal consistency reliability was measured using Cronbach's α coefficient and inter-item correlation. Test-retest was performed to examine the instrument's stability. Exploratory principal component analysis (PCA) with oblimin rotation was carried out to evaluate construct validity. Finally, the score on each item of the TCT was correlated with the person's Mini Mental State Examination (MMSE) and Barthel Index of activities of daily living scores. RESULTS A total of 51 persons participated, with a mean age of 86.7 (SD 6.6) years, of whom 46 were women with moderate-to-severe dementia [mean MMSE score 7.5 (SD 6.7)]. There were two measurement points 2 weeks apart. The results showed a satisfactory level for internal consistency and a high test-retest reliability (r = 0.76). The corrected item-total correlation ranged between 0.50 and 0.87, and a two-factor structure was revealed at the PCA. 'Vocalizing' seemed to measure another aspect of communication and was the only item which was negatively loaded. CONCLUSION Despite the low sample size in this study, the results revealed the TCT as a reliable and valid instrument, suitable for measuring communication among people with dementia. We suggest clarifying the understanding of 'vocalizing' before considering removing it from the scale.