Six box scores from a semi-structured interview with the participant and a study partner, combined into a global stage and a Sum of Boxes from 0 to 18. The CDR-SB is a primary endpoint in many early Alzheimer's disease trials.
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Memory
CDRMEMOrientation
CDRORIJudgment and problem solving
CDRJUDCommunity affairs
CDRCOMHome and hobbies
CDRHOMPersonal care
CDRCARAt a glance
In trials
Early Alzheimer's disease trials enrol people with mild cognitive impairment or mild dementia, where cognitive tests alone may not show whether a change matters in daily life. The CDR combines cognition with function, rated by a clinician who has heard from both the participant and someone who sees them every day. The Sum of Boxes gives a finer-grained score than the global stage, which is why it is used to measure slowing of decline.
The global CDR is used mostly for staging and eligibility: many trials require a global CDR of 0.5 or 1 at screening. Both are recorded on the same form; the global score follows the published algorithm and the Sum of Boxes is the arithmetic total of the six boxes.
The informant interview is not optional detail; it is half of the assessment. Record who the study partner is, their relationship to the participant and how often they see them, and aim to keep the same partner throughout the study. A change in informant can change the ratings.
Month 18
3 / 18
Structure
| Domain | Ratings | Main information source |
|---|---|---|
| Memory | 0, 0.5, 1, 2, 3 | Participant and informant |
| Orientation | 0, 0.5, 1, 2, 3 | Participant and informant |
| Judgment and problem solving | 0, 0.5, 1, 2, 3 | Participant and informant |
| Community affairs | 0, 0.5, 1, 2, 3 | Mainly informant |
| Home and hobbies | 0, 0.5, 1, 2, 3 | Mainly informant |
| Personal care | 0, 1, 2, 3 | Mainly informant |
The global CDR is derived with the published scoring rules. Raters should be trained and, in most trials, certified.
In Capture
Each domain is a dropdown with only the permitted values, so personal care cannot be given 0.5. The form records the rater and the study partner's relationship, and every change to a box score is captured in the field-level audit trail with a reason.
Weight changed 68.0 to 68.5 kg
Site coordinator · Reason: Transcription error
Query Q-0014 answered on Weight
Site coordinator · Reason: Source checked
Vital signs form locked
Data manager · Reason: Visit cleaned
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Rater quality
Because the CDR is a clinical judgement, rater differences can be as large as the treatment effect a trial hopes to detect. Sponsors usually require rater training and certification before a rater can score participants, keep the same rater for a participant wherever possible, and separate the CDR rater from the person managing treatment and adverse events so that side effects do not reveal the treatment arm.
Central review of a sample of interviews, where the protocol provides for it, helps detect drift. In the data, that means recording who rated each assessment and whether they were certified at the time, so reviewers can check rater consistency later.
Before go-live
Terms confirmed; rater training and certification planned.
Minimum contact per week and relationship recorded.
CDR rater independent of treatment and safety management.
Personal care without 0.5; all others 0 to 3 with 0.5.
Global CDR algorithm and CDR-SB in the analysis plan.
Global CDR range written into screening.
The total of the six domain box scores, from 0 to 18. It is widely used as an endpoint in early Alzheimer's disease trials.
With a published algorithm that weights memory most heavily. It gives a stage of 0, 0.5, 1, 2 or 3.
A trained clinician, after a semi-structured interview with the participant and a study partner.
The scale defines personal care ratings as 0, 1, 2 and 3 only. The form should allow only those values.
Most trials require rater training and certification before rating participants.
Box scores are stored as coded values, and the Sum of Boxes and global CDR are derived from them in analysis.
Structured CDR boxes with rater and informant. Free sandbox.