Validation of a new symptom impact questionnaire for mild to moderate cognitive impairment

Patient-reported outcomes assessment enhances the understanding of disease impact in a range of disorders. At mild levels of cognitive impairment the patient perspective on functioning, behavior and symptoms can be particularly valuable for syndrome characterization when clinical and neuropsychological findings are limited. We have evaluated the psychometric performance of the 55-item Patient-Reported Outcomes in Cognitive Impairment (PROCOG), a new patient-reported measure, to measure mild to moderate cognitive impairment symptoms and their impact from the perspective of patients with dementia of the Alzheimer's type (DAT) and mild cognitive impairment (MCI).

The sample of 75 DAT patients, 78 MCI patients and 33 cognitively intact control subjects (> 64 years) was recruited through medical centers in the U.SA. Validity was assessed through correlation to the Quality of Life--Alzheimer's Disease (QOL-AD) and Centers for Epidemiologic Studies--Depression Scale (CES-D) and neuropsychological assessments (WAIS subscales and MMSE).

PROCOG scores for MCI patients were generally intermediate between DAT and control subjects. Internal consistency and test-retest reliability were acceptable. Correlations with the CES-D and QOL-AD were in the moderate to high range; correlations with the neuropsychological measures were low to moderate.

The PROCOG demonstrated good to excellent psychometric properties among a sample of older adults with MCI and DAT as well as cognitively intact older adult control subjects and provides a method for collecting unique information on the patient experience of cognitive impairment. Subscales permit focused evaluation of domains relevant to the patient's experience of cognitive impairment.