Capital Bluecross CSF amyloid coverage update

Coverage criteria and policy statements

Covered and investigational uses

Coverage stance summarized from policy statements:

CSF biomarkers for diagnosis: Cerebrospinal fluid biomarker testing (amyloid beta peptides, tau protein, or neural thread proteins) as an adjunct to clinical diagnosis in individuals with mild cognitive impairment or mild dementia due to Alzheimer disease is considered investigational, except when CSF assessment of amyloid beta peptides and tau protein is used as part of an evaluation for initiation of amyloid beta targeting therapy, in which case it is considered medically necessary.

Neural thread protein testing is considered investigational even for therapy initiation; CSF biomarker testing for continuation of amyloid beta targeting therapy is considered investigational.

Covered services

Coverage and investigational designations are provided by code groupings in the policy; coverage depends on medical necessity and member benefits.

Covered when ALL of the following are met: Service is coded with one of the procedure codes listed under 'Covered when medically necessary' and is supported by documentation of medical necessity and member eligibility.

Providers must verify benefit coverage; identification of a code in the coding section does not denote coverage and not all covered services are eligible for separate reimbursement.

Investigational / Not covered

Not covered (investigational):

Not covered codes: Services billed with procedure codes listed in the 'Investigational and therefore not covered' code group are considered not covered (investigational).

Procedure codes explicitly listed under investigational/not covered (e.g., 81099 mapping to multiple U-codes such as 0207U, 0393U, 0412U, 0479U, 0503U, 0551U, 0568U) are excluded from coverage.

Cerebrospinal fluid (CSF) biomarker testing measures proteins such as amyloid beta peptides and tau that reflect Alzheimer disease pathology. As an adjunct to routine clinical diagnosis in individuals with mild cognitive impairment (MCI) or mild dementia, CSF testing is considered investigational because the evidence does not yet demonstrate improved net health outcomes or broadly validated cutoffs across general clinical populations.

An important exception is that CSF assessment of amyloid beta and tau may be used as part of the evaluation to determine eligibility for initiating FDA‑approved amyloid‑targeting therapies; in that specific context CSF testing is considered medically necessary. Neural thread protein testing in CSF is considered investigational even when evaluating for therapy initiation. CSF testing for continuation of amyloid‑targeting therapy is considered investigational.

Procedure codes explicitly listed under the policy's "Investigational and therefore not covered" section are excluded from coverage. Services billed with any of these investigational procedure codes will be considered not covered per the policy coding list.

Measurement of urinary biomarkers and most blood biomarker tests (including emerging plasma markers) as an adjunct to clinical diagnosis in individuals with MCI or mild dementia due to Alzheimer disease is considered investigational. Although plasma phosphorylated tau has shown promising diagnostic performance in studies, the evidence is insufficient to demonstrate improved health outcomes or generalizable clinical utility.

Therefore, urinary and blood biomarker testing performed for the purpose of adjunctive diagnostic evaluation in MCI or mild dementia are not considered medically necessary under this policy.

Final payment of claims is subject to verification that the service was medically necessary and that the member was eligible under the terms of their benefit program on the date of service. Identification of a code in the policy does not guarantee coverage or separate reimbursement; providers must confirm benefits and applicability for each member prior to billing.

Services that are billed with procedure codes designated as investigational in the policy may be denied as not covered. Documentation supporting medical necessity should be maintained and submitted when requested.

Procedure, diagnosis, and ancillary codes

Investigational and therefore not coveredCPTNot Covered

81099	Procedure Codes (listed as investigational/not covered)
0207U	Listed in investigational list (mapped to 83520 in document)
0393U	Listed in investigational list (mapped to 86849 in document)
0412U	Listed in investigational list
0479U	Listed in investigational list
0503U	Listed in investigational list
0551U	Listed in investigational list
0568U	Listed in investigational list

Covered when medically necessaryCPTCovered

0358U	Procedure Codes (listed as covered when medically necessary; mapped to several codes in the document)
0445U	Associated with 0358U in covered list
0459U	Associated with 0358U in covered list
82233	Associated with 0358U in covered list
82234	Associated with 0358U in covered list
84393	Associated with 0358U in covered list
84394	Associated with 0358U in covered list

Diagnosis / encounter codes shown in covered sectionICD-10

231.430	Encounter of female for testing for genetic disease carrier status for procreative management
231.440	Encounter of male for testing for genetic disease carrier status for procreative management
282.0	Family history related code (truncated description in document)

Coding list completeness note

Coding list completenessThe list of codes in this policy may not be all-inclusive; codes are subject to change at any time and identification of a code does not denote coverage — verify member benefits and reimbursement eligibility.

Order and maintenanceCodes in the document are presented in numerical order; updates to codes may be made administratively.

Coverage determinationCoverage is determined by member benefit terms and medical necessity; presence of a code in the policy does not guarantee payment.

Provider requirements, prior authorization, and billing guidance

Prior Authorization

Prior Authorization Required

Prior authorization is required for cerebrospinal fluid (CSF) biomarker testing when performed to evaluate eligibility for initiation of an FDA‑approved amyloid beta–targeting therapy. Confirm documentation includes indication for testing and that results will be used to establish amyloid pathology prior to therapy initiation.

Applicable when CSF testing (amyloid beta peptides and tau protein) is ordered to evaluate initiation of lecanemab (LEQEMBIO) or donanemab (Kisunla™).
Providers should check member benefits for prior authorization contact information and submission requirements before ordering.
Prior authorization does not guarantee eligibility — final coverage depends on member benefit plan and medical necessity determination.

Documentation Required

Confirmation of Amyloid Pathology Required for Therapy Initiation

Confirmation of amyloid pathology is required before initiating FDA‑approved amyloid beta–targeting therapy. Acceptable methods per trial and product labeling include a positive amyloid PET scan or CSF assessment demonstrating an abnormal t‑tau:Aβ42 (or equivalent CSF amyloid/tau) result.

Clinical background and context

Alzheimer disease is a progressive neurodegenerative disorder characterized by extracellular amyloid plaques and intracellular neurofibrillary tangles that lead to cognitive decline. Biomarkers have been developed to detect these pathologic processes and to estimate risk of progression from MCI to dementia.

Key cerebrospinal fluid biomarkers include Aβ42 (amyloid beta 42), total tau, and phosphorylated tau, which have been evaluated for diagnostic and prognostic performance. While CSF biomarkers generally show diagnostic accuracy comparable to amyloid PET for detecting amyloid pathology, between‑laboratory variability and lack of universally validated cutoffs limit generalizability.

Emerging blood biomarkers, notably plasma phosphorylated tau, show promise for screening and diagnosis but evidence is currently insufficient to establish that their use improves patient outcomes. Invasive testing (lumbar puncture) and the need for validated laboratory methods are additional considerations when ordering CSF biomarker assays.

Definitions and key terms

Key CSF biomarkers described

Core CSF biomarkersCSF amyloid beta-42 (Aβ42), total tau, and phosphorylated tau (e.g., p-tau181 or p-tau217).

Additional CSF markerNeurogranin — a synaptic/dendritic protein evaluated as a CSF marker for synaptic degeneration and prodromal AD.

Measurement variabilityBetween-laboratory variability in CSF biomarker measurement is large; commercially available kits differ by assay.

Amyloid beta targeting therapies

Examples of FDA-approved therapiesLEQEMBIO (lecanemab) and Kisunla (donanemab) are FDA‑approved amyloid beta targeting therapies referenced in the policy.

Label requirementProduct labels state that presence of amyloid beta pathology should be confirmed prior to initiating treatment.

OpenPayer

Evaluation of biomarkers for Alzheimer disease

Coverage criteria and policy statements

Procedure, diagnosis, and ancillary codes

Provider requirements, prior authorization, and billing guidance

Clinical background and context

Definitions and key terms