Introduction: Test the validity and reliability of the Quick Dementia Rating System (QDRS), a rapid dementia staging tool.
Methods: The QDRS was tested in 267 patient-caregiver dyads compared with Clinical Dementia Ratings (CDR), neuropsychological testing, and gold standard measures of function, mood, and behavior. Psychometric properties including, item variability, floor and ceiling effects, concurrent and construct validity, and internal consistency were determined. The QDRS was used to derive an independent CDR and sum of boxes. Interscale reliability between QDRS and CDR was tested using intraclass correlation coefficients (ICC). Area under the receiver operator characteristic curves (AUC) tested discrimination properties of QDRS across CDR stages.
Results: QDRS scores increased with higher CDR staging and poorer neuropsychological performance (p's <.001). The QDRS demonstrated low floor and ceiling effects; excellent known-groups validity across CDR stages (p's<.001); construct validity against cognitive, behavioral, and functional measures (p-value's:0.004 to <0.001); and reliability (Cronbach α: 0.86-0.93). The QDRS demonstrated differential scores across different dementia etiologies. The AUC for the QDRS was 0.911 (95%CI 0.86-0.96) and for the CDR-SB was 0.996 (95% CI: 0.99-1.0) demonstrating comparable ability to discriminate normal controls from dementia. The QDRS-generated CDR demonstrated excellent correspondence with the CDR (ICC=0.90) and sum-of-boxes (ICC=0.92).
Discussion: The QDRS validly and reliably differentiates individuals with and without dementia and accurately stages dementia without extensive training or clinician input, and is highly correlated with our gold standard measures. The QDRS provides a rapid method to determine study eligibility; stage patients in clinical practice; and improve case ascertainment in population studies.
Keywords: Clinical Dementia Rating; Clinical Trials; Dementia; Staging; neurocognitive disorders.