Blood Tests for ALS Provide Highly Accurate Diagnosis and Prognosis
Head-to-head study shows four blood-based Neurofilament Light Chain assays reliably identify amyotrophic lateral sclerosis and forecast disease course without invasive procedures.
Topline
Recent research demonstrates that blood tests measuring serum neurofilament light chain (NfL) can accurately diagnose amyotrophic lateral sclerosis (ALS) and forecast patient survival, offering clinicians and patients valuable diagnostic and prognostic tools without invasive procedures.
Study Background
A study conducted in southern France, recently published in Neurology, assessed the accuracy of four commercial laboratory platforms in diagnosing ALS and predicting its progression. The study included 139 ALS patients (average age 67 years, 50% women) and 70 control participants without ALS (average age 64 years, 41% women).
ALS diagnosis is challenging, often requiring extensive and invasive testing. Reliable blood-based biomarkers like NfL can significantly reduce diagnostic uncertainty, expedite care decisions, and simplify patient enrollment in clinical trials.
Methodology
Participants provided a single blood sample analyzed using four different technologies: the ultrasensitive Simoa system, microfluidic Ella cartridge, and the hospital-grade automated analyzers Lumipulse and Elecsys. Researchers also assessed two other serum markers (GFAP and pTau181) for comparison. Follow-up durations averaged 42 months for ALS patients and about 142 months for controls.
Researchers evaluated:
Accuracy of each method in distinguishing ALS from non-ALS cases.
Ability of NfL levels to predict patient survival outcomes.
Key Findings
High accuracy across platforms: All four assays produced highly consistent results, with correlation coefficients between 0.94–0.96.
Reliable diagnostic performance: The platforms demonstrated high diagnostic accuracy, with areas under the ROC curve ranging from 0.889 (Simoa) to 0.912 (Lumipulse). Ella (0.906) and Elecsys (0.910) also performed very well.
Significant prognostic value: Patients whose NfL levels exceeded established thresholds had significantly lower survival rates at 50 weeks compared to those with lower levels. Hazard ratios indicated a 4.4–5.4 times higher risk of mortality.
Limited utility of GFAP and pTau181: These markers showed poor diagnostic performance, suggesting NfL as the superior biomarker for ALS diagnosis.
Implications for Practice
These findings suggest several important applications for clinical care:
For patients: A blood-based NfL test could provide earlier answers in cases where ALS is suspected but not confirmed. It may also give patients and families clearer insight into disease progression and help guide decisions about care and planning.
For healthcare providers: Clinicians can use NfL assays as an adjunct to standard diagnostic tools to reduce uncertainty. Prognostic cutoffs offer a meaningful way to discuss expected disease course.
For research and health systems: These assays can help streamline clinical trial enrollment and potentially reduce healthcare costs by decreasing time to diagnosis and avoiding unnecessary tests.