Validity and Reliability of the Clock Drawing Test in older people

Early diagnosis of cognitive disorders in order to initiate new efficient treatments in time is an important task which cannot be fulfilled without proper cognitive screening tools. The Clock Drawing Test (CDT) is a simple inexpensive cognitive screening tool which can be used in primary care settings delivering health services to older people. The aim of this study was to assess validity and reliability of the CDT in Iranian older population. Method and Materials: In this study the CDT and Mini Mental State Examination (MMSE) were concurrently performed on 74 literate participants aged 60 and over. Participants were recruited from the clients of Iran Alzheimer’s Association (dementia patients and non-demented clients، including other patients or care givers) during a 5 month period. The CDT was performed by two trained raters using Shulman’s six points scoring method. Using SPSS version 20، reliability was assessed measuring kappa statistics as well as ICC. Concurrent validity between CDT and MMSE were statistically analyzed by spearman’s rank correlation coefficient. Mean age of the participants was 72 years in a range of 60 to 90 years with equal numbers 0f male and female participants. Kappa statistics for test retest reliability was 0. 554 (p<0. 001). ICC for inter rater reliability was 0. 964 (p<0. 001). Spearman’s rank correlation coefficient for MMSE and CDT scores was 0. 782، statistically significant at p<0. 001. CDT is a valid and reliable test in literate older people that can be used as a cognitive screening tool in Iranian older population.