Entropy of Real-World Gait in Parkinson's Disease Determined from Wearable Sensors as a Digital Marker of Altered Ambulatory Behavior.

Parkinson's disease (PD) is a common age-related neurodegenerative disease. Gait impairment is frequent in the later stages of PD contributing to reduced mobility and quality of life. Digital biomarkers such as gait velocity and step length are predictors of motor and cognitive decline in PD. Additional gait parameters may describe different aspects of gait and motor control in PD. Sample entropy (SampEnt), a measure of signal predictability, is a nonlinear approach that quantifies regularity of a signal. This study investigated SampEnt as a potential biomarker for PD and disease duration. Real-world gait data over a seven-day period were collected using an accelerometer (Axivity AX3, York, UK) placed on the low back and gait metrics extracted. SampEnt was determined for the stride time, with vector length and threshold parameters optimized. People with PD had higher stride time SampEnt compared to older adults, indicating reduced gait regularity. The range of SampEnt increased over 36 months for the PD group, although the mean value did not change. SampEnt was associated with dopaminergic medication dose but not with clinical motor scores. In conclusion, this pilot study indicates that SampEnt from real-world data may be a useful parameter reflecting clinical status although further research is needed involving larger populations.

Clinical efficacy of oral alendronate in ankylosing spondylitis: a randomised placebo-controlled trial.

OBJECTIVES: A prospective, double blind, randomised, placebo controlled trial over 2 years was performed to test the efficacy of alendronate, an oral aminobisphosphonate, in improving symptoms and arrest disease progression in patients with mild to severe ankylosing spondylitis (AS). METHODS: 180 patients with AS were randomised to receive weekly alendronate 70 mg or placebo (1:1 randomisation). BAS-G was the primary outcome measure with Bath indices as secondary outcomes. Vertebral x-rays were performed at 0 and 24 months. Biomarkers (including CRP, IL-1beta, IL6, VEGF, MMP-1, and MMP-3) were collected during the first 12 months. RESULTS: There was no significant difference between the placebo and treatment groups in any of the recorded outcomes over the 2 years including clinical indices, biomarkers, and radiology. The change in BAS-G, the primary outcome measure, was -0.21 for the treatment group and -0.42 for the placebo group p=0.57. Change in all other clinical outcome measures were also non-significant; BASDAI p=0.86, BASFI p=0.37, BASMI p=0.021. Sub-group analysis of those subjects with a baseline BASDAI >4 were also non-significant. CONCLUSIONS: This prospective study demonstrates that alendronate 70mg weekly for 2 years was no more efficacious than placebo in improving clinical or laboratory measures of disease activity or measures of physical impact in subjects with mild to severe active AS. TRIAL REGISTRATION: ID SRCTN12308164, registered on 15.12.2015.

Association of cytokine and matrix metalloproteinase profiles with disease activity and function in ankylosing spondylitis.

INTRODUCTION: The pathology of ankylosing spondylitis (AS) suggests that certain cytokines and matrix metalloproteinases (MMPs) might provide useful markers of disease activity. Serum levels of some cytokines and MMPs have been found to be elevated in active disease, but there is a general lack of information about biomarker profiles in AS and how these are related to disease activity and function. The purpose of this study was to investigate whether clinical measures of disease activity and function in AS are associated with particular profiles of circulating cytokines and MMPs. METHODS: Measurement of 30 cytokines, five MMPs and four tissue inhibitors of metalloproteinases was carried out using Luminex® technology on a well-characterised population of AS patients (n = 157). The relationship between biomarker levels and measures of disease activity (Bath ankylosing spondylitis disease activity index (BASDAI)), function (Bath ankylosing spondylitis functional index) and global health (Bath ankylosing spondylitis global health) was investigated. Principal component analysis was used to reduce the large number of biomarkers to a smaller set of independent components, which were investigated for their association with clinical measures. Further analyses were carried out using hierarchical clustering, multiple regression or multivariate logistic regression. RESULTS: Principal component analysis identified eight clusters consisting of various combinations of cytokines and MMPs. The strongest association with the BASDAI was found with a component consisting of MMP-8, MMP-9, hepatocyte growth factor and CXCL8, and was independent of C-reactive protein levels. This component was also associated with current smoking. Hierarchical clustering revealed two distinct patient clusters that could be separated on the basis of MMP levels. The high MMP cluster was associated with increased C-reactive protein, the BASDAI and the Bath ankylosing spondylitis functional index. CONCLUSIONS: A profile consisting of high levels of MMP-8, MMP-9, hepatocyte growth factor and CXCL8 is associated with increased disease activity in AS. High MMP levels are also associated with smoking and worse function in AS.