Linking the Clinical Dementia Rating Scale-Sum of Boxes, the Clinician’s Interview-Based Impression Plus Caregiver Input, and the Clinical Global Impression Scale: Evidence based on Individual Participant Data from Five Randomized Clinical Trials of Donepezil

Article type: Research Article

Authors: Samara, Myrto^{a; b; *} | Levine, Stephen Z.^c | Yoshida, Kazufumi^d | Goldberg, Yair^e | Cipriani, Andrea^{f; g} | Efthimiou, Orestis^{h; i} | Iwatsubo, Takeshi^j | Leucht, Stefan^a | Furakawa, Toshiaki A.^d

Affiliations: [a] Department of Psychiatry and Psychotherapy, Technical University of Munich, School of Medicine, Munich, Germany | [b] 3rd Department of Psychiatry, School of Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece | [c] Department of Community Mental Health, University of Haifa, Haifa, Israel | [d] Department of Health Promotion and Human Behavior, Kyoto University Graduate School of Medicine/School of Public Health, Kyoto, Japan | [e] Faculty of Industrial Engineering and Management, Technion, Haifa, Israel | [f] Department of Psychiatry, University of Oxford, Oxford, UK | [g] Oxford Health NHS Foundation Trust, Warneford Hospital, Oxford, UK | [h] Institute of Social and Preventive Medicine (ISPM); University of Bern, Switzerland | [i] Department of Psychiatry, University of Oxford, Oxford, UK | [j] University of Tokyo, Bunkyo-ku, Tokyo, Japan

Correspondence: [*] Correspondence to: Myrto Samara, MD, PhD, Aristotle University of Thessaloniki, Thessaloniki, Greece; Technische Universität München, Munich, Germany. Tel.: +306980107450; E-mail: samaramyrto@gmail.com.

Abstract: Background:In patients with Alzheimer’s disease, global assessment scales, such as the Clinical Dementia Rating-Sum of Boxes (CDR-SB), the Clinician’s Interview-Based Impression Plus Caregiver Input (CIBI plus), and the Clinical Global Impression (CGI) are commonly used. Objective:To clinically understand and interpret the associations between these scales, we examined the linkages for the total and change scores of CDR-SB, CIBI plus, and CGI. Methods:Individual participant data (N = 2,198) from five pivotal randomized placebo-controlled trials of donepezil were included. Data were collected at baseline and scheduled visits for up to 6 months. Spearman’s correlation coefficients ρ were examined between corresponding total and change scores of simultaneous CDR-SB, CIBI plus, and CGI ratings. To link between the simultaneous ratings, equipercentile linking was used. Results:We found strong evidence that the Spearman’s correlation coefficients between the CDR-SB and CGI, and CDR-SB and CIBI plus total scores were at least adequately correlated (ρ= 0.50 to 0.71, with p < 0.01). The correlation coefficients between the change scores of CDR-SB and CGI were deemed adequate for weeks 6 to 24 (ρ= 0.44 to 0.65); the remaining correlations were smaller in magnitude (ρ= 0.09 to 0.35). Overall, the linkages were in-line with expectations, e.g., CDR-SB range score of 3-4 (= very mild dementia) was linked to a CGI score of 3 (= mildly ill), and an increase of CDR-SB of 1 was linked to a change of 5 (= minimal worsening) in both CGI and CIBI plus. Conclusion:The study findings can be useful for clinicians wishing to compare scores of different scales across patients. They can also help researchers understand results of studies using different scales and can facilitate meta-analyses, to increase statistical power.

Keywords: Alzheimer’s disease, clinical dementia rating-sum of boxes, clinical global impression, clinician’s interview-based impression of change, clinician’s interview-based impression of severity, global ratings, minimal clinically important difference

DOI: 10.3233/JAD-201541

Journal: Journal of Alzheimer's Disease, vol. 82, no. 3, pp. 1075-1084, 2021