Reader response: Blood NfL: A biomarker for disease severity and progression in Parkinson disease
Anoukevan Rumund, MD, Radboudumc
Tainá M.Marques, MSc, Radboudumc
Rianne A.J.Esselink, MD, PhD, Radboudumc
Bastiaan R.Bloem, MD, PhD, Radboudumc
Marcel M.Verbeek, PhD, Radboudumc
Submitted November 22, 2019
The recent article by Lin et al.,1 described blood neurofilament light chain (NfL) both as a diagnostic biomarker to distinguish between controls, patients with Parkinson disease (PD), and patients with multiple system atrophy (MSA), and as a progression biomarker for PD.
Our recent observations (published in Neurology2) showed that serum NfL levels could separate PD from MSA with good diagnostic accuracy (AUC 0.892 vs. 0.801), in agreement with Lin et al. However, in contrast with this study, PD patients in our cohort had NfL levels similar to non-neurological controls, possibly, because their disease severity was less.
The authors also found a positive correlation between blood NfL and markers of disease progression (H&Y, UPDRS-III and MMSE) in PD patients. We could not confirm these associations in our cohort using Spearman correlation and (multivariate) regression analysis, which may be explained by the similar blood NfL levels in PD patients and controls in our population. Perhaps, the correlation between NfL and progression is only present in advanced PD. However, their results should be interpreted with caution, since the NfL cutoff values and correlation analyses between progression and blood NfL were done in the same population, which may infer a risk of circularity. Furthermore, the definition of ≥2 points decline on UPDRS-III for motor progression and ≥2 points on MMSE for cognitive decline casts doubt about its clinical relevance.
In both cohorts,1,2 blood NfL could discriminate PD well from MSA. However, the results for blood NfL as either a potential biomarker for PD versus healthy controls or as a potential progression biomarker in PD are inconsistent. Perhaps, NfL is only elevated in more advanced PD, when the diagnosis is unambiguous and the need for a diagnostic or progression biomarker is less urgent.
Disclosure
The authors report no relevant disclosures. Contact journal@neurology.org for full disclosures.
References
Lin CH, Li CH, Yang KC, et al. Blood NfL: A biomarker for disease severity and progression in Parkinson disease. Neurology 2019;93:e1104–e1111.
Marques TM, van Rumund A, Oeckl P, et al. Serum NFL discriminates Parkinson disease from atypical parkinsonisms. Neurology 2019;92:e1479–e1486.
The recent article by Lin et al.,1 described blood neurofilament light chain (NfL) both as a diagnostic biomarker to distinguish between controls, patients with Parkinson disease (PD), and patients with multiple system atrophy (MSA), and as a progression biomarker for PD.
Our recent observations (published in Neurology2) showed that serum NfL levels could separate PD from MSA with good diagnostic accuracy (AUC 0.892 vs. 0.801), in agreement with Lin et al. However, in contrast with this study, PD patients in our cohort had NfL levels similar to non-neurological controls, possibly, because their disease severity was less.
The authors also found a positive correlation between blood NfL and markers of disease progression (H&Y, UPDRS-III and MMSE) in PD patients. We could not confirm these associations in our cohort using Spearman correlation and (multivariate) regression analysis, which may be explained by the similar blood NfL levels in PD patients and controls in our population. Perhaps, the correlation between NfL and progression is only present in advanced PD. However, their results should be interpreted with caution, since the NfL cutoff values and correlation analyses between progression and blood NfL were done in the same population, which may infer a risk of circularity. Furthermore, the definition of ≥2 points decline on UPDRS-III for motor progression and ≥2 points on MMSE for cognitive decline casts doubt about its clinical relevance.
In both cohorts,1,2 blood NfL could discriminate PD well from MSA. However, the results for blood NfL as either a potential biomarker for PD versus healthy controls or as a potential progression biomarker in PD are inconsistent. Perhaps, NfL is only elevated in more advanced PD, when the diagnosis is unambiguous and the need for a diagnostic or progression biomarker is less urgent.
Disclosure
The authors report no relevant disclosures. Contact journal@neurology.org for full disclosures.
References