Performance-Based Assessment of Instrumental Activities of Daily Living: Validation of the Sydney Test of Activities of Daily Living in Memory Disorders (STAM).

OBJECTIVES

The distinction between dementia and mild cognitive impairment (MCI) relies upon the evaluation of independence in instrumental activities of daily living (IADL). Self- and informant reports are prone to bias. Clinician-based performance tests are limited by long administration times, restricted access, or inadequate validation. To close this gap, we developed and validated a performance-based measure of IADL, the Sydney Test of Activities of Daily Living in Memory Disorders (STAM).

DESIGN

Prospective cohort study (Sydney Memory and Ageing Study).

SETTING

Eastern Suburbs, Sydney, Australia.

PARTICIPANTS

554 community-dwelling individuals (54% female) aged 76 and older with normal cognition, MCI, or dementia.

MEASUREMENTS

Activities of daily living were assessed with the STAM, administered by trained psychologists, and the informant-based Bayer-Activities of Daily Living Scale (B-ADL). Depressive symptoms were measured with the Geriatric Depression Scale (15-item version). Cognitive function was assessed with a comprehensive neuropsychological test battery. Consensus diagnoses of MCI and dementia were made independently of STAM scores.

RESULTS

The STAM showed high interrater reliability (r = 0.854) and test-retest reliability (r = 0.832). It discriminated significantly between the diagnostic groups of normal cognition, MCI, and dementia with areas under the curves ranging from 0.723 to 0.948. A score of 26.5 discriminated between dementia and nondementia with a sensitivity of 0.831 and a specificity of 0.864. Correlations were low with education (r = 0.230) and depressive symptoms (r = -0.179), moderate with the B-ADL (r = -0.332), and high with cognition (ranging from r = 0.511 to r = 0.594). The mean time to complete the STAM was 16 minutes.

CONCLUSIONS

The STAM has good psychometric properties. It can be used to differentiate between normal cognition, MCI, and dementia and can be a helpful tool for diagnostic classification both in clinical practice and research.