The staging of dementia severity is important for clinical and research purposes, with the CDR being one of the most commonly used instruments. To our knowledge, however, there are no published guidelines available for staging dementia severity based on CDR-SOB scores. In the present sample, 93.0% of participants (AD, MCI, and control groups) were staged correctly using the proposed CDR-SOB score guidelines ().
Sum of Boxes Staging Category
Previous research suggests that CDR-SOB scores may have potential for discriminating between patients with MCI and very early AD who are assigned a global CDR score of 0.5. Gmndman et al,16
analyzing data from the Memory lmpairment Study,17
found that patients with MCI (global CDR score of 0.5) were assigned significantly lower CDR-SOB scores (mean [SD] score, 1.8 [0.8]) than were patients with very mild AD who also were assigned a global score of 0.5 (mean [SD] score, 3.0 [0.8]). When restricting analyses to patients with MCI and AD who were assigned a global CDR score of 0.5, the present study found a nearly 3-fold increased risk of being diagnosed as having AD for every 1-point increment in CDR-SOB scores, which is slightly higher than hut consistent with a previous investigation7
that found an odds ratio of 2.3 for the diagnosis of dementia in patients with a CDR score of 0.5.
As mentioned previously, CDR-SOB scores for staging dementia severity offer several advantages over the global score. The present results can be used to further expand on the potential for increased precision in tracking change across time. Tracking progression in AD studies has traditionally been conducted using the global CDR score, with primary end points being transitioned from one category (eg, mild AD, global CDR of 1) to another (eg, moderate AD, global CDR of 2). The proposed guidelines afford a more precise interpretation of progression. For example, the present results suggest that mild AD spans CDR-SOB scores from 4.5 to 9.0, whereas moderate AD spans CDR-SOB scores from 9.5 to 15.5. Therefore, using the global CDR score, there would be no way to distinguish between a patlent who progresses from a score of 4.5 to 9.5 and one who progresses from a score of 9.0 to 9.5, although both have progressed from mild to moderate AD. The present guidelines also afford researchers the ability to monitor progression within stages (eg, mild AD) in addition to between stages of dementla.
The present results demonstrate that CDR-SOB scores can be used to accurately stage patients with AD, and interpretive guidelines are presented. These data also demonstrate that CDR-SOB scores can, with reasonable accuracy, discriminate between patients with very early AD and those with MCI, which is impossible using global CDR scores owing to the nature of the scale. However, given that this study did not analyze other forms of mild dementia syndromes (eg, frontotemporal dementia or Parkinson disease), the generalizability of the guidelines should be tested with additional patient populations. These results offer clinicians and researchers alike an alternative interpretive strategy for the CDR that affords greater precision in patient care and analysis.