Reliability and sensitivity of two clock drawing test rubrics as screening measures for mild cognitive impairment

Abstract

AbstractBackgroundEarly identification of mild cognitive impairment (MCI) is critical, as MCI precipitates disability and may be a precursor to major neurocognitive disorder. The Clock Drawing Test (CDT) is a widely adopted screening measure for dementia however it is not known whether paper‐and‐pencil CDT scoring rubrics are sensitive to subtle losses consistent with MCI. We examined the reliability and sensitivity to MCI of two free‐drawn Clock Drawing Test rubrics ‐ the 10‐point Rouleau, and the 20‐point Clock Drawing Interpretation Scale (CDIS) in community‐dwelling older adults.Method345 adults enrolled in a study of functional cognition completed the Montreal Cognitive Assessment (MoCA), the Alzheimer’s Disease Cooperative Study Scale (ADCS‐ADL), and freely‐drawn clocks scored with CDIS and Roleau rubrics. We computed Cronbach’s alpha, receiver operating characteristic (ROC) analyses using the MoCA as the index measure, and one‐way ANOVAs with the ADCS‐ADL for each rubric.ResultOur sample was 74% female, 83.2% white. Mean age was 70.01 ±8.89, and mean education was 15.5 ±3.735 years. Average scores were 24.28 ±3.44 (MoCA), 74.85 ±4.16 (ADCS), 8.8 ±1.68 (Rouleau) and 18.17 ±2.09 (CDIS). alphas were .65 for the CDIS and .479 for the Rouleau. ROC analyses using MoCA scores consistent with any impairment (<26) resulted in a CDIS AOC of .677, with sensitivity of .681 and specificity of .58 at a cut score of 19. The Rouleau AOC was .684, with sensitivity of .542 and specificity of .76 at a cut score of 9. ANOVAs indicated that individuals classified as impaired by the CDIS ((F = 13.095, p<.001) or the Rouleau (F = 22.2, p<.001) rubrics reported significantly more ADL/IADL difficulties than those classified as unimpaired with either rubric. Differences between impaired and unimpaired groups were larger for the CDIS, suggesting this rubric is more sensitive to ADL/IADL deficits.ConclusionBoth rubrics produced generally similar results when compared to the MoCA and adequately identified individuals needing further evaluation given reported functional problems. The CDIS produced more robust differences suggesting that it may be more appropriate for community screening to identify individuals in need of comprehensive cognitive and functional evaluation.