Tanujit Dey

Quantification of the Balance Error Scoring System with Mobile Technology.

PURPOSE The aim of this project was to develop a biomechanically based quantification of the Balance Error Scoring System (BESS) using data derived from the accelerometer and gyroscope of a mobile tablet device. METHODS Thirty-two healthy young adults completed the BESS while an iPad was positioned at the sacrum. Data from the iPad were compared to position data gathered from a three-dimensional motion capture system. Peak-to-peak (P2P), normalized path length (NPL), and root mean squared (RMS) were calculated for each system and compared. Additionally, a 95% ellipsoid volume, iBESS volume, was calculated using center of mass (CoM) movements in the anteroposterior (AP), mediolateral (ML), and trunk rotation planes of movement to provide a comprehensive, 3D metric of postural stability. RESULTS Across all kinematic outcomes, data from the iPad were significantly correlated with the same outcomes derived from the motion capture system (rho range, 0.37-0.94; P < 0.05). The iBESS volume metric was able to detect a difference in postural stability across stance and surface, showing a significant increase in volume in increasingly difficult conditions, whereas traditional error scoring was not as sensitive to these factors. CONCLUSIONS The kinematic data provided by the iPad are of sufficient quality relative to motion capture data to accurately quantify postural stability in healthy young adults. The iBESS volume provides a more sensitive measure of postural stability than error scoring alone, particularly in conditions 1 and 4, which often suffer from floor effects, and condition 5, which can experience ceiling effects. The iBESS metric is ideally suited for clinical and in the field applications in which characterizing postural stability is of interest.

Generalized Inverted Exponential Distribution: Different Methods of Estimation

SYNOPTIC ABSTRACT In this article we consider various methods of estimation of the unknown parameters of a generalized inverted exponential distribution from a frequentist as well as Bayesian perspective. With regard to Bayes estimation of the unknown parameters under squared error loss function, we assume that the scale and shape parameters of the distribution have a gamma prior and are independently distributed. Under these priors, we use an importance sampling technique to calculate Bayes estimates and the corresponding highest posterior density intervals. We also compute approximate Bayes estimates using Lindley’s approximation. Besides Bayes estimation, we introduce maximum likelihood estimates and estimates based on percentiles. Monte Carlo simulations are performed to compare the performance of the Bayes estimates with the classical estimates. Two datasets have been analyzed for illustrative purposes.

Two-parameter Maxwell distribution: Properties and different methods of estimation

In this article we consider the problem of estimating location and scale parameters of the Maxwell distribution from both frequentist and Bayesian points of view. Additionally, some properties of the distribution, namely, stochastic ordering, Rényi and Shannon entropies, and order statistics, are derived. Behavior of the estimators from different frequentist approaches, namely, maximum likelihood, method of moments, least square’s, and weighted least square as well as Bayes estimators of parameters, is compared with respect to bias, mean squared errors, and the coverage percentage extracted from bootstrap confidence intervals. The existence and uniqueness of the maximum likelihood estimators are also discussed. The Bayes estimators and the associated credible intervals are obtained using importance sampling technique under squared error loss function. A gamma prior is used for the scale parameter and a uniform prior for the location parameter. An example with flood-level data is used to illustrate applicability of procedures discussed.

Patient Characteristics Associated With Severe Hypoglycemia in a Type 2 Diabetes Cohort in a Large, Integrated Health Care System From 2006 to 2015

OBJECTIVE To identify severe hypoglycemia events, defined as emergency department visits or hospitalizations for hypoglycemia, in patients with type 2 diabetes receiving care in a large health system and to identify patient characteristics associated with severe hypoglycemia events. RESEARCH DESIGN AND METHODS This was a retrospective cohort study from January 2006 to December 2015 using the electronic medical record in the Cleveland Clinic Health System (CCHS). Participants included 50,439 patients with type 2 diabetes receiving care in the CCHS. Number of severe hypoglycemia events and associated patient characteristics were identified. RESULTS The incidence proportion of severe hypoglycemia increased from 0.12% in 2006 to 0.31% in 2015 (P = 0.01). Compared with patients who did not experience severe hypoglycemia, those with severe hypoglycemia had similar median glycosylated hemoglobin (HbA1c) levels. More patients with severe hypoglycemia versus those without had a prior diagnosis of nonsevere hypoglycemia (9% vs. 2%, P < 0.001). Logistic regression confirmed an increased odds for severe hypoglycemia with insulin, sulfonylureas, increased number of diabetes medications, history of nonsevere hypoglycemia (odds ratio [OR] 3.01, P < 0.001), HbA1c <6% (42 mmol/mol) (OR 1.95, P < 0.001), black race, and increased Charlson comorbidity index. Lower odds of severe hypoglycemia were noted with higher BMI and use of metformin, dipeptidyl peptidase 4 inhibitors, and glucagon-like peptide 1 agonists. CONCLUSIONS In this retrospective study of patients with type 2 diabetes with severe hypoglycemia, patient characteristics were identified. Patients with severe hypoglycemia had previous nonsevere hypoglycemia diagnoses more frequently than those without. Identifying patients at high risk at the point of care can allow for change in modifiable risk factors and prevention of severe hypoglycemia events.

Aerobic Exercise Preserves Olfaction Function in Individuals with Parkinson’s Disease

Introduction. Based on anecdotal reports of improved olfaction following aerobic exercise, the aim of this study was to evaluate the effects of an 8-week aerobic exercise program on olfaction function in individuals with Parkinsons disease (PD). Methods. Thirty-eight participants with idiopathic PD were randomized to either an aerobic exercise group (n = 23) or a nonexercise control group (n = 15). The aerobic exercise group completed a 60-minute cycling session three times per week for eight weeks while the nonexercise control group received no intervention. All participants completed the University of Pennsylvania Smell Identification Test (UPSIT) at baseline, end of treatment, and a four-week follow up. Results. Change in UPSIT scores between the exercise and nonexercise groups from baseline to EOT (p = 0.01) and from baseline to EOT+4 (p = 0.02) favored the aerobic exercise group. Individuals in the nonexercise group had worsening olfaction function over time, while the exercise group was spared from decline. Discussion. The difference in UPSIT scores suggested that aerobic exercise may be altering central nervous system pathways that regulate the physiologic or cognitive processes controlling olfaction in individuals with PD. While these results provide promising preliminary evidence that exercise may modify the disease process, further systematic evaluation is necessary.

Quantifying the Complexity of Time Series With Applications to Postural Balance Studies of Parkinson's Patients

ABSTRACT The article provides a quantitative assessment of the complexity of random time series via the tool of ε-complexity. The methods is then applied to quantify differences in balance dynamics between Parkinsonian and non-Parkinsonian subjects via the time-dependent data obtained by acceleration measurements for the subjects asked to maintain standing postural balance on hard and soft surfaces. Finally, a comparison of the above novel method with the more classical correlational, and spectral methodologies is carried out. Although all three techniques provide clear separation between the Parkinsonian subjects and controls, it is the complexity analysis of the acceleration signals that separates the two categories most efficiently.

Dual-task Interference Disrupts Parkinson's Gait Across Multiple Cognitive Domains

Gait dysfunction, a hallmark of Parkinsons disease, contributes to a relatively high incidence of falling. Gait function is further diminished during the performance of a motor-cognitive task (i.e., dual-task). It is unclear if Parkinsons disease-related dual-task deficits are related to a specific area of cognitive function or are the result of a more global decline in executive function. The aim of this project was to systematically evaluate gait performance to determine if gait dysfunction is restricted to certain types of executive function or a global phenomenon in individuals with Parkinsons disease. Twenty-three individuals with mild-moderate Parkinsons disease completed a series of dual-task conditions in which gait was paired with cognitive tasks requiring: working memory (0, 1, and 2-back), attention and problem solving (serial-7 subtraction), verbal memory (digit recall), semantic memory (Controlled Oral Word Association) and information processing speed (visual Stroop test). The results demonstrate that individuals with mild-moderate Parkinsons disease have a generalized worsening of spatial-temporal gait parameters regardless of the specific cognitive demand being performed concurrently. Overall, gait velocity decreased (p < 0.01) and stride and stance time both increased (p < 0.01) across all cognitive conditions. The attention and problem solving task resulted in the greatest number of gait parameter decrements. Results indicated that performance on cognitive tasks remained unchanged from single-task to dual-task conditions. Diminished gait performance under dual-task conditions across different cognitive function domains suggests a global Parkinsons disease-related deficit in information processing and regulation of gait.

Effect of glycemic control on the Diabetes Complications Severity Index score and development of complications in people with newly diagnosed type 2 diabetes: 在新诊断的2型糖尿病患者中血糖控制情况对糖尿病并发症严重程度指数评分以及并发症进展的影响

The aim of the present study was to assess the longitudinal accumulation of diabetes‐related complications and the effect of glycemic control on the Diabetes Complications Severity Index (DCSI) score in people with newly diagnosed type 2 diabetes (T2D).

Normative Performance on the Balance Error Scoring System by Youth, High School, and Collegiate Athletes

CONTEXT   Annually, more than 1 million youth athletes in the United States receive or are suspected of receiving a concussion. The Balance Error Scoring System (BESS) is the most commonly used clinical balance evaluation designed to provide a better understanding of the motor-control processes of individuals with concussion. Despite the widespread use of the BESS, a fundamental gap exists in applying this tool to young athletes, as normative values are lacking for this population. OBJECTIVE   To determine age- and sex-specific normative values for the BESS in youth, high school, and collegiate athletes. DESIGN   Cross-sectional study. SETTING   Local youth sport organizations, high schools, and colleges. PATIENTS OR OTHER PARTICIPANTS   Student-athletes (N = 6762) completed preseason baseline concussion testing as part of a comprehensive concussion-management program. Groups were youth males aged 5 to 13 years (n = 360), high school males aged 14 to 18 years (n = 3743), collegiate males aged 19 to 23 years (n = 497), youth females aged 5 to 13 years (n = 246), high school females aged 14 to 18 years (n = 1673), and collegiate females aged 19 to 23 years (n = 243). MAIN OUTCOME MEASURE(S)   Errors according to the BESS specifications. RESULTS   Performance on the BESS was worse ( P < .01) in youth athletes than in high school and collegiate athletes. In the youth and high school cohorts, females exhibited better scores than males ( P < .05). Sex was not a factor for collegiate athletes. Data from the youth cohort were further subdivided into 4-year bins to evaluate potential motor-development differences. The error count was highest for 5- to 9-year-old males and decreased with age. CONCLUSIONS   Performance on the BESS depended on sex and age, particularly in youth athletes. These sex- and age-specific normative values provide a reference to facilitate and unify clinical decision making across multiple providers caring for youth athletes with concussions.

Three-dimensional evaluation of postural stability in Parkinson’s disease with mobile technology

BACKGROUND Postural instability is a hallmark of Parkinsons disease. Objective metrics to characterize postural stability are necessary for the development of treatment algorithms to aid in the clinical setting. OBJECTIVE The aim of this project was to validate a mobile device platform and resultant three-dimensional balance metric that characterizes postural stability. METHODS A mobile Application was developed, in which biomechanical data from inertial sensors within a mobile device were processed to characterize movement of center of mass in the medial-lateral, anterior-posterior and trunk rotation directions. Twenty-seven individuals with Parkinsons disease and 27 age-matched controls completed various balance tasks. A postural stability metric quantifying the amplitude (peak-to-peak) of sway acceleration in each movement direction was compared between groups. The peak-to-peak value in each direction for each individual with Parkinsons disease across all trials was expressed as a normalized value of the control data to identify individuals with severe postural instability, termed Cleveland Clinic-Postural Stability Index. RESULTS In all conditions, the balance metric for peak-to-peak was significantly greater in Parkinsons disease compared to controls (p < 0.01 for all tests). CONCLUSIONS The balance metric, in conjunction with mobile device sensors, provides a rapid and systematic metric for quantifying postural stability in Parkinsons disease.