Usefulness of Cerebrospinal Fluid Alzheimer's disease biomarkers in older patients: Evidence from a national multicenter prospective study.

BACKGROUND

The use of cerebrospinal (CSF) biomarkers in the diagnosis of Alzheimer's disease (AD) has been gaining interest in clinical practice. Although their usefulness has been demonstrated, their potential value in older patients remains debated.

OBJECTIVES

To assess whether knowledge of the results of CSF AD biomarkers was associated with the same gain in diagnostic confidence in older adults > 80 than in younger patients.

DESIGN

Prospective multicenter study, including memory clinics physicians who completed a two-part questionnaire for all their patients addressing the requirement for assessment of Alzheimer's disease biomarkers in CSF proposed as part of routine care during the study period.

SETTING

30 secondary or tertiary memory clinics in France.

MEASUREMENTS

Clinicians indicated their diagnosis hypothesis and an estimate of their diagnostic confidence [scale 1-10]. Receiver operating characteristic (ROC) analysis, including the calculation of the area under the curve (AUC), was conducted using logistic regression to evaluate the diagnostic performance of CSF AD biomarkers.

RESULTS

In 813 consecutive patients, median age 70 [interquartile range (IQR) = 63 - 77] including 132 patients over 80 years, we observed a similar confidence gain in CSF biomarkers between older and younger patients, both for AD and non-AD diagnoses. In older patients, the added value of CSF biomarkers was greater when CSF biomarkers indicated AD profile whereas the initial hypothesis was "non-AD", leading to a final diagnosis of AD (2.4 ± 1.6 versus 1.1 ± 2.1, p-value, p = 0.03). ROC analyses showed similar performance of AD CSF biomarkers in older and younger patients.

CONCLUSION

CSF AD biomarkers added substantial value to clinical assessment in patients over 80. Their use seems crucial in the diagnostic process for older adults referred to memory clinics.