Abstract
Many cognitive screening instruments are available to assess patients with cognitive symptoms in whom a diagnosis of dementia or mild cognitive impairment is being considered. Most are quantitative scales with specified cut-off values. In contrast, the cognitive disorders examination or Codex is a two-step decision tree which incorporates components from the Mini-Mental State Examination (MMSE) (three word recall, spatial orientation) along with a simplified clock drawing test to produce categorical outcomes defining the probability of dementia diagnosis and, by implication, directing clinician response (reassurance, monitoring, further investigation, immediate treatment). Codex has been shown to have high sensitivity and specificity for dementia diagnosis but is less sensitive for the diagnosis of mild cognitive impairment (MCI). We examined minor modifications to the Codex decision tree to try to improve its sensitivity for the diagnosis of MCI, based on data extracted from studies of two other cognitive screening instruments, the Montreal Cognitive Assessment and Free-Cog, which are more stringent than MMSE in their tests of delayed recall. Neither modification proved of diagnostic value for mild cognitive impairment. Possible explanations for this failure are considered.
Highlights
The cognitive disorders examination or Codex for the detection of dementia described by Belmin et al [1,2] is a two-step decision tree for diagnostic prediction, developed by identifying independent variables related to dementia using a multivariable logistic model
In the modified Codex decision tree derived from MoCA (Figure 1b), there were five delayed recall components but only two spatial orientation components [12], whereas in modified Codex derived from Free-Cog (Figure 1c), there were five delayed recall components but only three spatial orientation components
Baseline demographic data from the studies examining original Codex and modified Codex derived from MoCA or Free-Cog are shown in Table 1, along with the distribution of observed Codex categories versus diagnosis for each formulation of the decision tree (Figure 2)
Summary
The cognitive disorders examination or Codex for the detection of dementia described by Belmin et al [1,2] is a two-step decision tree for diagnostic prediction, developed by identifying independent variables related to dementia using a multivariable logistic model. Binary recursive partitioning incorporated the three-word recall and spatial orientation components from the Mini-Mental State. Examination (MMSE) [3] along with a simplified clock drawing test (sCDT, scored 1 or 0, respectively, normal and abnormal) to produce four terminal nodes, the endpoint values having different probabilities of dementia diagnosis (categories A–D, respectively, with very low, low, high, and very high probability of dementia; Figure 1a). Codex had both high sensitivity and specificity for the diagnosis of dementia (0.92 and 0.85, respectively) [1].
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
