Correlation analysis of the in-clinic and telephone batteries from the AREDS cognitive function ancillary study. AREDS Report No. 15.

PURPOSE: To determine whether the AREDS Telephone Battery can be substituted for the In-Clinic Cognitive Function Battery to assess cognitive function, so that participants could still provide follow-up information without having to come to the clinic.
METHODS: Correlation analysis was performed on scores of the following in-clinic and telephone administrations: 1) Modified Mini-Mental State Examination (3MS), conducted in person vs. Telephone Interview Cognitive Status (TICS-M); 2) Wechsler Memory Scale-III (WMS-III), Logical Memory I and II; 3) Digits Backwards (a sub-test of the WMS-R); 4) Verbal Fluency; and 5) Letter Fluency (F,A,S).
RESULTS: A total of 1,738 AREDS participants completed an In-Clinic Battery and a Telephone Battery within twelve months. Significant positive correlations were found for all tests, ranging from rho = 0.89 between the 3MS and TICS-M scores (95% CI; 0.88 - 0.90), to rho = 0.71 for Letter Fluency (95% CI; 0.68 - 0.74).
CONCLUSION: The linear relationships between the In-Clinic Battery and Telephone Battery scores support the hypothesis that the Telephone Battery is an appropriate substitute for participants who are unable to complete an in-clinic assessment of cognitive function.