A Cost Effective Method of Identifying and Recruiting Persons Over 80 Free of Dementia or Mild Cognitive Impairment

Abstract

For observational or prevention studies, accurately identifying by mail and telephone cognitively normal elderly volunteers would be cost effective. We describe how to recruit cognitively normal sib-pairs over age 80 using commercially available lists by age and ZIP code. We mailed an Institutional Review Board-approved letter to 24,366 persons over 85 around Jacksonville, FL, and received approximately 3,000 postcard replies with approximately 500 answering 3 screening statements affirmatively. Of these, we recruited 128 persons who underwent both in-person and telephone evaluations, the latter using the Telephone Interview of Cognitive Status-modified (TICS-m) and Clinical Dementia Rating scale (CDR). Blinded to the TICS-m and CDR data, clinicians made a consensus diagnosis for each participant, 120 were normal and 8 had mild cognitive impairment. With CDR, 119 patients (93%) screened as normal, and of these 115 (97%) were confirmed as normal with the consensus diagnosis. A TICS-m score cut-off of <29 resulted in a similar proportion of normals in the screened sample (97% or 103/106); however, 13 normal volunteers would have been excluded because they scored <29 on the TICS-m. Supplementing the sample, we recruited 12 age-matched cases having consensus diagnosis of dementia (n=2) or mild cognitive impairment (n=10). A CDR>0 correctly identified 12/12, whereas the TICS-m <29 correctly identified 7/12. Hearing loss present in 50% did not influence TICS-m or CDR performance. Using stringent entry criteria and the telephone CDR, this method accurately identified normal elderly persons.