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Evidence summaries

CSF Tau and the CSF Tau/Abeta Ratio for the Diagnosis of Alzheimer's Disease Dementia and other Dementias in People with Mild Cognitive Impairment (Mci)

The evidence is insufficient regarding the value of CSF testing of t-tau, p-tau or p-tau/ABeta ratio for the diagnosis of Alzheimer's disease. These tests might possibly have better sensitivity than specificity and therefore might have greater utility in ruling it out as opposed to ruling it in. Level of evidence: "D"

Comment: The quality of evidence is downgraded by study quality (high dropout rates) inconsistency (heterogeneity in thresholds) and imprecise results (wide confidence intervals).

Summary

A Cochrane review [Abstract] 1 included 15 studies with a total of 1282 subjects with MCI at baseline. Out of them 1172 had analysable data; 430 participants converted to Alzheimer's disease dementia and 130 participants to other forms of dementia. Follow-up in the majority of studies was from one to three years.

  • The accuracy of the CSF total tau (t-tau): It was evaluated in 7 studies (291 cases and 418 non-cases).The sensitivity values ranged from 51% to 90% while the specificity values ranged from 48% to 88%. At the median specificity of 72%, the estimated sensitivity was 75% (95% CI 67 to 85), the positive likelihood ratio was 2.72 (95% CI 2.43 to 3.04), and the negative likelihood ratio was 0.32 (95% CI 0.22 to 0.47).
  • The accuracy of the CSF phosphorylated tau (p-tau): It was evaluated in 6 studies (164 cases and 328 non-cases). The sensitivities were between 40% and 100%, while the specificities were between 22% and 86%. At the median specificity of 47.5%, the estimated sensitivity was 81% (95% CI: 64 to 91), the positive likelihood ratio was 1.55 (CI 1.31 to 1.84), and the negative likelihood ratio was 0.39 (CI: 0.19 to 0.82).
  • The accuracy of the CSF p-tau/ABeta ratio: It was evaluated in 5 studies (140 cases and 293 non-cases) . The sensitivities were between 80% and 96% while the specificities were between 33% and 95%.
  • The accuracy of CSF t-tau/ABeta ratio: It was evaluated in 2 studies. The sensitivities were 50% and 51%, and specificities were 91% and 96%, respectively.

The accuracy of these CSF biomarkers for ‘other dementias' had not been investigated in the included primary studies.

Clinical comments

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Date of latest search:

    References

    • Ritchie C, Smailagic N, Noel-Storr AH et al. CSF tau and the CSF tau/ABeta ratio for the diagnosis of Alzheimer's disease dementia and other dementias in people with mild cognitive impairment (MCI). Cochrane Database Syst Rev 2017;3():CD010803. [PubMed]

Primary/Secondary Keywords