Health Technology Assessment of Diagnostic Approaches in Alzheimer's Disease

Novel Diagnostic Approaches for the Diagnosis of Alzheimer's Disease: Technology Assessment and Clinical Effectiveness

Background: New research criteria for the diagnosis of Alzheimer's disease (AD) have recently been developed to enable an early diagnosis of AD pathophysiology by relying on emerging biomarkers. To enable efficient allocation of health care resources, evidence is needed to support decision makers on the adoption of emerging biomarkers in clinical practice. The research goals are to 1) assess the diagnostic test accuracy (of current clinical diagnostic work-up and emerging biomarkers in Magnetic Resonance Imaging (MRI), Positron Emission Tomography (PET) and Cerebrospinal Fluid (CSF), 2) perform a cost-consequence analysis and 3) assess long-term cost-effectiveness by an economic model.

Methods/design: In a cohort design 304 consecutive patients suspected of having a primary neurodegenerative disease are approached in four academic memory clinics and followed for two years. Clinical data and data on quality of life data, costs and emerging biomarkers are gathered.

Diagnostic test accuracy is determined by relating the clinical practice and new research criteria diagnoses to the reference diagnosis. The clinical practice diagnosis at baseline is reflected by a consensus procedure among experts using clinical information only (no biomarkers). The diagnosis based on the new research criteria is reflected by decision rules that combine clinical and biomarker information. The reference diagnosis is determined by a consensus procedure among experts based on clinical information on the course of symptoms over a two-year time period.

A decision analytic model is build combining available evidence from different resources among which (accuracy) results from the study, literature and expert opinion to assess long-term cost-effectiveness of the emerging biomarkers.

Discussion: Several other multi-centre trials study the relative value of new biomarkers for early evaluation of AD and related disorders. The uniqueness of this study is the assessment of resource utilization and quality of life to enable an economic evaluation. The study results are generalizable to a population of patients who are referred to a memory clinic due to their memory problems.

Inclusion Criteria:

• All new consecutive patients of the participating memory clinics who are suspected of having a primary neurodegenerative disease. This means all patients with subjective and/or objective memory complaints.
• CDR 0, 0.5 or 1
• MMSE score must be 20 or higher.
• Availability of a reliable informer or proxy (who visits or contacts the patient at least once a week).

Exclusion Criteria:

• Normal Pressure Hydrocephalus (NPH)
• Huntington's disease
• Recent Transient Ischaemic Attack (TIA) (<2 years) or Cerebral Vascular Accident (CVA) or TIA/CVA followed by cognitive impairment (within 3 months)
• History of Schizophrenia, other psychotic disorders (< 12 months)
• Major depression (< 12 months)
• Alcohol abuse
• Brain-tumor, epilepsy, encephalitis
• Absence of a reliable informant
• Probably not available for follow-up