Prevalence and Risk Factors of Distal Symmetric Polyneuropathy Among Predominantly Non-Hispanic Black, Low-Income Patients

BACKGROUND AND OBJECTIVES

Distal symmetric polyneuropathy (DSP) is a disabling, often painful condition associated with falls and reduced quality of life. Non-Hispanic Black people and people with low income are underrepresented in existing DSP studies; therefore, it is unknown whether data accurately reflect the prevalence, risk factors, and burden of disease in these populations.

METHODS

Patients older than 40 years presenting to an outpatient internal medicine clinic predominantly serving Medicaid patients in Flint, Michigan, were enrolled in a cross-sectional study. Demographics, clinical characteristics, including medication use, anthropomorphic measurements, fasting lipids, and hemoglobin A1c were collected. DSP was defined using the modified Toronto Clinical Neuropathy Score (mTCNS). Multivariable logistic regression was performed to model DSP and undiagnosed DSP as a function of potential risk factors age, metabolic syndrome, and race. DSP burden was measured using Peripheral Neuropathy Quality of Life Instrument-97.

RESULTS

Two hundred participants were enrolled, and 169 (85%) completed all data collection. The population was 55% female of mean age (SD) 58.2 years (10.4) and 69% non-Hispanic Black. Among the population, 50% had diabetes, 67% had metabolic syndrome, and 47% had a household income <$20,000. DSP was present in 73% of the population, of which 75% were previously undiagnosed. Neuropathic pain was documented in 57% of participants with DSP. DSP based on mTCNS criteria was associated with older age (odds ratio [OR] 1.1 [95% confidence interval (CI) 1.03-1.2]) and metabolic syndrome (OR 4.4 [1.1-18.1]). Non-Hispanic Black participants had lower odds of DSP (OR 0.1 [0.01-0.4]) than non-Hispanic White and Hispanic participants. DSP burden was high, including increased pain, health-related worry, and poorer quality of life (all p < 0.001).

DISCUSSION

DSP is extremely common and often underrecognized in this predominantly non-Hispanic Black, low-income population and leads to substantial disease burden. Metabolic syndrome is a highly prevalent, modifiable risk factor in this population that should be managed to lower DSP prevalence.

Burden of Neurologic Health Care and Incident Neurologic Diagnoses in the Year After COVID-19 or Influenza Hospitalization

BACKGROUND AND OBJECTIVE

Following the outbreak of viral infections from the severe acute respiratory syndrome coronavirus 2 virus in 2019 (coronavirus disease 2019 [COVID-19]), reports emerged of long-term neurologic sequelae in survivors. To better understand the burden of neurologic health care and incident neurologic diagnoses in the year after COVID-19 vs influenza, we performed an analysis of patient-level data from a large collection of electronic health records (EMR).

METHODS

We acquired deidentified data from TriNetX, a global health research network providing access to EMR data. We included individuals aged 18 years or older during index event, defined as hospital-based care for COVID-19 (from April 1, 2020, until November 15, 2021) or influenza (from 2016 to 2019). The study outcomes were subsequent health care encounters over the following year for 6 neurologic diagnoses including migraine, epilepsy, stroke, neuropathy, movement disorders, and dementia. We also created a composite of the 6 diagnoses as an incident event, which we call "incident neurologic diagnoses." We performed a 1:1 complete case nearest-neighbor propensity score match on age, sex, race/ethnicity, marital status, US census region patient residence, preindex years of available data, and Elixhauser comorbidity score. We fit time-to-event models and reported hazard ratios for COVID-19 vs influenza infection.

RESULTS

After propensity score matching, we had a balanced cohort of 77,272 individuals with COVID-19 and 77,272 individuals with influenza. The mean age was 51.0 ± 19.7 years, 57.7% were female, and 41.5% were White. Compared with patients with influenza, patients with COVID-19 had a lower risk of subsequent care for migraine (HR 0.645, 95% CI 0.604-0.687), epilepsy (HR 0.783, 95% CI 0.727-0.843), neuropathies (HR 0.567, 95% CI 0.532-0.604), movement disorders (HR 0.644, 95% CI 0.598-0.693), stroke (HR 0.904, 95% CI 0.845-0.967), or dementia (HR 0.931, 95% CI 0.870-0.996). Postinfection incident neurologic diagnoses were observed in 2.79% of the COVID-19 cohort vs 4.91% of the influenza cohort (HR 0.618, 95% CI 0.582-0.657).

DISCUSSION

Compared with a matched cohort of adults with a hospitalization or emergency department visit for influenza infection, those with COVID-19 had significantly fewer health care encounters for 6 major neurologic diagnoses over a year of follow-up. Furthermore, we found that COVID-19 infection was associated with a lower risk of an incident neurologic diagnosis in the year after infection.

Streamlining Prior Authorization to Improve Care

This Viewpoint addresses the challenges of prior authorization: decreased access, delayed care, decreased patient satisfaction and outcomes, and increased clinician burnout.

Prescription Opioid Initiation for Neuropathy, Headache, and Low Back Pain: A US Population-based Medicare Study

Neuropathy, headache, and low back pain (LBP) are common conditions requiring pain management. Yet little is known regarding whether access to specialists impacts opioid prescribing. We aimed to identify factors associated with opioid initiation among opioid-naïve older adults and evaluate how access to particular specialists impacts prescribing. This retrospective cohort study used a 20% Medicare sample from 2010 to 2017. Opioid initiation was defined as a first opioid prescription filled within 12 months after a diagnosis encounter. Disease-related opioid initiation was defined as a first opioid prescription filled within 7 days following a disease-specific claim. Logistic regression using generalized estimating equations was used to determine the association of patient demographics, provider types, and regional physician specialty density with disease-related opioid initiation, accounting for within-region correlation. We found opioid initiation steadily declined from 2010 to 2017 (neuropathy: 26-19%, headache: 31-20%, LBP: 45-32%), as did disease-related opioid initiation (4-3%, 12-7%, 29-19%) and 5 to 10% of initial disease-related prescriptions resulted in chronic opioid use within 12 months of initiation. Certain specialist visits were associated with a lower likelihood of disease-related opioid initiation compared with primary care. Residence in high neurologist density regions had a lower likelihood of disease-related opioid initiation (headache odds ratio [OR] .76 [95% CI: .63-.92]) and LBP (OR .7 [95% CI: .61-.81]) and high podiatrist density regions for neuropathy (OR .56 [95% CI: .41-.78]). We found that specialist visits and greater access to specialists were associated with a lower likelihood of disease-related opioid initiation. These data could inform strategies to perpetuate reductions in opioid use for these common pain conditions. PERSPECTIVE: This article presents how opioid initiation for opioid-naïve patients with newly diagnosed neuropathy, headache, and LBP varies across providers. Greater access to certain specialists decreased the likelihood of opioid initiation. Future work may consider interventions to support alternative treatments and better access to specialists in low-density regions.

Cost and utilization of healthcare services for persons with diabetes

AIMS

Describe and compare healthcare costs and utilization for insured persons with type 1 diabetes (T1D), type 2 diabetes (T2D), and without diabetes in the United States.

METHODS

Using a nationally representative healthcare claims database, we identified matched persons with T1D, T2D, and without diabetes using a propensity score quasi-randomization technique. In each year between 2009 and 2018, we report costs (total and out-of-pocket) and utilization for all healthcare services and those specific to medications, diabetes-related supplies, visits to providers, hospitalizations, and emergency department visits.

RESULTS

In 2018, we found out-of-pocket costs and total costs were highest for persons with T1D (out-of-pocket: $2,037.2, total: $25,652.0), followed by T2D (out-of-pocket: $1,543.3, total: $22,408.1), and without diabetes (out-of-pocket: $1,122.7, total: $14,220.6). From 2009 to 2018, out-of-pocket costs were increasing for persons with T1D(+6.5 %) but decreasing for T2D (-7.5 %) and without diabetes (-2.3 %). Medication costs made up the largest proportion of out-of-pocket costs regardless of diabetes status (T1D: 51.4 %, T2D: 55.4 %,without diabetes: 51.1 %).

CONCLUSIONS

Given the substantial out-of-pocket costs for people with diabetes, especially for those with T1D, providers should screen all persons with diabetes for financial toxicity (i.e., wide-ranging problems stemming from healthcare costs). In addition, policies that aim to lower out-of-pocket costs of cost-effective diabetes related healthcare are needed with a particular focus on medications.

Patient Travel Distance to Neurologist Visits

BACKGROUND AND OBJECTIVES

The density of neurologists within a given geographic region varies greatly across the United States. We aimed to measure patient travel distance and travel time to neurologist visits, across neurologic conditions and subspecialties. Our secondary goal was to identify factors associated with long-distance travel for neurologic care.

METHODS

We performed a cross-sectional analysis using a 2018 Medicare sample of patients with at least 1 outpatient neurologist visit. Long-distance travel was defined as driving distance ≥50 miles 1-way to the visit. Travel time was measured as driving time in minutes. Multilevel generalized linear mixed models with logistic link function, which accounted for clustering of patients within hospital referral region and allowed modeling of region-specific random effects, were used to determine the association of patient and regional characteristics with long-distance travel.

RESULTS

We identified 563,216 Medicare beneficiaries with a neurologist visit in 2018. Of them, 96,213 (17%) traveled long distance for care. The median driving distance and time were 81.3 (interquartile range [IQR]: 59.9-144.2) miles and 90 (IQR: 69-149) minutes for patients with long-distance travel compared with 13.2 (IQR: 6.5-23) miles and 22 (IQR: 14-33) minutes for patients without long-distance travel. Comparing across neurologic conditions, long-distance travel was most common for nervous system cancer care (39.6%), amyotrophic lateral sclerosis [ALS] (32.1%), and MS (22.8%). Many factors were associated with long-distance travel, most notably low neurologist density (first quintile: OR 3.04 [95% CI 2.41-3.83] vs fifth quintile), rural setting (4.89 [4.79-4.99]), long-distance travel to primary care physician visit (3.6 [3.51-3.69]), and visits for ALS and nervous system cancer care (3.41 [3.14-3.69] and 5.27 [4.72-5.89], respectively). Nearly one-third of patients bypassed the nearest neurologist by 20+ miles, and 7.3% of patients crossed state lines for neurologist care.

DISCUSSION

We found that nearly 1 in 5 Medicare beneficiaries who saw a neurologist traveled ≥50 miles 1-way for care, and travel burden was most common for lower-prevalence neurologic conditions that required coordinated multidisciplinary care. Important potentially addressable predictors of long-distance travel were low neurologist density and rural location, suggesting interventions to improve access to care such as telemedicine or neurologic subspecialist support to local neurologists. Future work should evaluate differences in clinical outcomes between patients with long-distance travel and those without.

Association between brain health outcomes and metabolic risk factors in persons with diabetes

We performed a cross-sectional study to determine associations between cognition and MRI-derived brain outcomes, with obesity, diabetes duration, and metabolic risk factors in 51 Pima American Indians with longstanding type 2 diabetes (T2d) (mean [SD] age: 48.4 [11.3] years, T2d duration: 20.1 [9.1] years). Participants had similar cognition (NIH Toolbox Cognition Battery composite: 45.3 [9.8], p = 0.64, n = 51) compared to normative data. T2d duration, but not other metabolic risk factors, associated with decreased cortical thickness (Point Estimate (PE): -0.0061, 95%CI: -0.0113, -0.0009, n = 45), gray matter volume (PE: -830.39, 95%CI: -1503.14, -157.64, n = 45), and increased white matter hyperintensity volume (PE: 0.0389, 95%CI: 0.0049, 0.0729, n = 45).

Diabetic Neuropathies

OBJECTIVE

This article provides an up-to-date review of the diagnosis and management of the most common neuropathies that occur in patients with diabetes.

LATEST DEVELOPMENTS

The prevalence of diabetes continues to grow worldwide and, as a result, the burden of diabetic neuropathies is also increasing. Most diabetic neuropathies are caused by hyperglycemic effects on small and large fiber nerves, and glycemic control in individuals with type 1 diabetes reduces neuropathy prevalence. However, among people with type 2 diabetes, additional factors, particularly metabolic syndrome components, play a role and should be addressed. Although length-dependent distal symmetric polyneuropathy is the most common form of neuropathy, autonomic syndromes, particularly cardiovascular autonomic neuropathy, are associated with increased mortality, whereas lumbosacral radiculoplexus neuropathy and treatment-induced neuropathy cause substantial morbidity. Recent evidence-based guidelines have updated the recommended treatment options to manage pain associated with distal symmetric polyneuropathy of diabetes.

ESSENTIAL POINTS

Identifying and appropriately diagnosing the neuropathies of diabetes is key to preventing progression. Until better disease-modifying therapies are identified, management remains focused on diabetes and metabolic risk factor control and pain management.

The effect of surgical weight loss on diabetes complications in individuals with class II/III obesity

AIMS/HYPOTHESIS

The aim of this study was to determine the effect of bariatric surgery on diabetes complications in individuals with class II/III obesity (BMI > 35 kg/m2).

METHODS

We performed a prospective cohort study of participants with obesity who underwent bariatric surgery. At baseline and 2 years following surgery, participants underwent metabolic phenotyping and diabetes complication assessments. The primary outcomes for peripheral neuropathy (PN) were a change in intra-epidermal nerve fibre density (IENFD, units = fibres/mm) at the distal leg and proximal thigh, the primary outcome for cardiovascular autonomic neuropathy (CAN) was a change in the expiration/inspiration (E/I) ratio, and the primary outcome for retinopathy was a change in the mean deviation on frequency doubling technology testing.

RESULTS

Among 127 baseline participants, 79 completed in-person follow-up (age 46.0 ± 11.3 years [mean ± SD], 73.4% female). Participants lost a mean of 31.0 kg (SD 18.4), and all metabolic risk factors improved except for BP and total cholesterol. Following bariatric surgery, one of the primary PN outcomes improved (IENFD proximal thigh, +3.4 ± 7.8, p<0.01), and CAN (E/I ratio -0.01 ± 0.1, p=0.89) and retinopathy (deviation -0.2 ± 3.0, p=0.52) were stable. Linear regression revealed that a greater reduction in fasting glucose was associated with improvements in retinopathy (mean deviation point estimate -0.7, 95% CI -1.3, -0.1).

CONCLUSIONS/INTERPRETATION

Bariatric surgery may be an effective approach to reverse PN in individuals with obesity. The observed stability of CAN and retinopathy may be an improvement compared with the natural progression of these conditions; however, controlled trials are needed.

Patient and health care provider knowledge of diabetes and diabetic microvascular complications: a comprehensive literature review

Diabetic retinopathy, neuropathy, and nephropathy occur in more than 50% of people with diabetes, contributing substantially to morbidity and mortality. Patient understanding of these microvascular complications is essential to ensure early recognition and treatment of these sequalae as well as associated symptoms, yet little is known about patient knowledge of microvascular sequalae. In this comprehensive literature review, we provide an overview of existing knowledge regarding patient knowledge of diabetes, retinopathy, neuropathy, and nephropathy. We also discuss health care provider's knowledge of these sequalae given that patients and providers must work together to achieve optimal care. We evaluated 281 articles on patient and provider knowledge of diabetic retinopathy, neuropathy, and nephropathy as well as predictors of improved knowledge and screening practices. Results demonstrated that patient and provider knowledge of microvascular sequalae varied widely between studies, which may reflect sociocultural or methodologic differences. Knowledge assessment instruments varied between studies with limited validation data and few studies controlled for confounding. Generally, improved patient knowledge was associated with greater formal education, longer diabetes duration, and higher socioeconomic status. Fewer studies examined provider knowledge of sequalae, yet these studies identified multiple misconceptions regarding appropriate screening practices for microvascular complications and the need to screen patients who are asymptomatic. Further investigations are needed that use well validated measures, control for confounding, and include diverse populations. Such studies will allow identification of patients and providers who would benefit from interventions to improve knowledge of microvascular complications and, ultimately, improve patient outcomes.

Costs and Utilization of New-to-Market Neurologic Medications

BACKGROUND AND OBJECTIVES

The objective of this study was to compare the utilization and costs (total and out-of-pocket) of new-to-market neurologic medications with existing guideline-supported neurologic medications over time.

METHODS

We used a healthcare pharmaceutical claims database (from 2001 to 2019) to identify patients with both a diagnosis of 1 of 11 separate neurologic conditions and either a new-to-market medication or an existing guideline-supported medication for that condition. Neurologic conditions included orthostatic hypotension, spinal muscular atrophy, Duchenne disease, Parkinson disease, multiple sclerosis, amyotrophic lateral sclerosis, myasthenia gravis, Huntington disease, tardive dyskinesia, transthyretin amyloidosis, and migraine. New-to-market medications were defined as all neurologic medications approved by the US Food and Drug Administration (FDA) between 2014 and 2018. In each year, we determined the median out-of-pocket and standardized total costs for a 30-day supply of each medication. We also measured the proportion of patients receiving new-to-market medications compared with all medications specific for the relevant condition.

RESULTS

We found that the utilization of most new-to-market medications was small (<20% in all but 1 condition), compared with existing, guideline-supported medications. The out-of-pocket and standardized total costs were substantially larger for new-to-market medications. The median (25th percentile, 75th percentile) out-of-pocket costs for a 30-day supply in 2019 were largest for edaravone ($712.8 [$59.8-$802.0]) and eculizumab ($91.1 [$3.0-$3,216.4]). For new-to-market medications, the distribution of out-of-pocket costs was highly variable and the trends over time were unpredictable compared with existing guideline-supported medications.

DISCUSSION

Despite the increasing number of FDA-approved neurologic medications, utilization of newly approved medications in the privately insured population remains small. Given the high costs and similar efficacy for most of the new medications, limited utilization may be appropriate. However, for new medications with greater efficacy, future studies are needed to determine whether high costs are a barrier to utilization.

The Effect of Surgical Weight Loss on Cognition in Individuals with Class II/III Obesity

BACKGROUND

Obesity is a global epidemic and is associated with cognitive impairment and dementia. It remains unknown whether weight loss interventions, such as bariatric surgery, can mitigate cognitive impairment.

OBJECTIVES

We aimed to determine the effect of surgical weight loss on cognition in individuals with class II/III obesity.

DESIGN

We performed a prospective cohort study of participants who underwent bariatric surgery. At baseline and two years following surgery, participants completed metabolic risk factor and neuropsychological assessments.

SETTING

Participants were enrolled from an academic suburban bariatric surgery clinic.

PARTICIPANTS

There were 113 participants who completed baseline assessments and 87 completed two-year follow-up assessments (66 in-person and 21 virtual) after bariatric surgery. The mean (SD) age was 46.8 (12.5) years and 64 (73.6%) were female.

INTERVENTION

Bariatric surgery. There were 77 (88.5%) participants that underwent sleeve gastrectomy and 10 (11.5%) that underwent gastric bypass surgery.

MEASUREMENTS

Cognition was assessed using the NIH toolbox cognitive battery (NIHTB-CB) and the Rey Auditory Verbal Learning Test (AVLT). The primary outcome was the change in NIHTB-CB fluid composite score before and after surgery.

RESULTS

The primary outcome, NIHTB-CB composite score, was stable following bariatric surgery (-0.4 (13.9), p=0.81,n=66). Among secondary outcomes, the NIHTB-CB dimensional card sorting test (executive function assessment), improved (+6.5 (19.9),p=0.01,n=66) while the Rey AVLT delayed recall test (memory assessment) declined (-0.24 (0.83),p=0.01,n=87) following surgery. Improvements to metabolic risk factors and diabetes complications were not associated with improvements to NIHTB-CB composite score. The other 4 NIHTB-CB subtests and Rey AVLT assessments of auditory learning and recognition were stable at follow-up.

CONCLUSIONS

Following bariatric surgery, the age-adjusted composite cognitive outcome did not change, but an executive subtest score improved. These results suggest that bariatric surgery may mitigate the natural history of cognitive decline in individuals with obesity, which is expected to be faster than normal aging, but confirmatory randomized controlled trials are needed. The decline in delayed recall also warrants further studies to determine potential differential effects on cognitive subtests.

Diagnostic characteristics of nerve conduction study parameters for vasculitic neuropathy

INTRODUCTION/AIMS

In vasculitic neuropathy (VN), a 50% side-to-side difference in the amplitude of compound muscle action potentials and sensory nerve action potentials is considered meaningful, but unequivocal evidence is lacking. The aim of this study is to characterize electrodiagnostic features that best distinguish VN from other axonal polyneuropathies.

METHODS

We conducted a case-control study between January 2000 and April 2021. We reviewed the records of patients with VN who had bilateral nerve conduction studies (NCS) and evaluated different electrodiagnostic models to help distinguish VN from non-inflammatory axonal polyneuropathies.

RESULTS

We identified 82 cases, and 174 controls with non-inflammatory axonal neuropathies. The amplitude percent difference Z-score model showed the best discriminatory capability between cases and controls (area under the curve [AUC] 0.87; 95% confidence interval [CI] 0.82, 0.93), and the number of nerves tested did not significantly influence the model. Individually, the ulnar motor nerve (AUC 0.86; 95% CI 0.77, 0.94) and median motor nerve (AUC 0.85; 95% CI 0.77, 0.94) showed the best discriminatory capability. A 50% amplitude difference between at least two bilateral nerves, either in the upper (AUC 0.85; 95% CI 0.77, 0.93) or lower (AUC 0.79; 95% CI 0.71, 0.87) extremity showed good discriminatory threshold for detecting VN.

DISCUSSION

The best electrodiagnostic criteria for VN utilizes z-scores of percent differences in nerve amplitudes, but this approach may be difficult to implement at the bedside. Alternately, a 50% amplitude difference in at least two nerves is a reasonable approximation.

Towards prevention of diabetic peripheral neuropathy: clinical presentation, pathogenesis, and new treatments

Diabetic peripheral neuropathy (DPN) occurs in up to half of individuals with type 1 or type 2 diabetes. DPN results from the distal-to-proximal loss of peripheral nerve function, leading to physical disability and sometimes pain, with the consequent lowering of quality of life. Early diagnosis improves clinical outcomes, but many patients still develop neuropathy. Hyperglycaemia is a risk factor and glycaemic control prevents DPN development in type 1 diabetes. However, glycaemic control has modest or no benefit in individuals with type 2 diabetes, probably because they usually have comorbidities. Among them, the metabolic syndrome is a major risk factor for DPN. The pathophysiology of DPN is complex, but mechanisms converge on a unifying theme of bioenergetic failure in the peripheral nerves due to their unique anatomy. Current clinical management focuses on controlling diabetes, the metabolic syndrome, and pain, but remains suboptimal for most patients. Thus, research is ongoing to improve early diagnosis and prognosis, to identify molecular mechanisms that could lead to therapeutic targets, and to investigate lifestyle interventions to improve clinical outcomes.

Changes in the Use of Brand Name and Generic Medications and Total Prescription Cost Among Medicare Beneficiaries With Epilepsy

BACKGROUND AND OBJECTIVE

To characterize trends in antiseizure medication (ASM) fills and total prescription costs in people with epilepsy.

METHODS

This was a retrospective cohort study of beneficiaries with epilepsy (ASM, plus ICD codes) in a 20% random Medicare sample, with continuous Fee-For-Service coverage (Parts A, B, and D) in 2008-2018. We summed the number of pill days and costs (adjusted to 2018 dollars) per person-year for each ASM. ASMs were categorized into brand vs generic, first vs newer generation, and enzyme inducers vs noninducers.

RESULTS

There were 77,000-133,000 beneficiaries with epilepsy per year. The most common ASM was phenytoin in 2008, which shifted to levetiracetam in 2018 (2008: phenytoin 25%, levetiracetam 14%; 2018: phenytoin 9%, levetiracetam 27%). Brand name (2008: 56%; 2018: 14%), first-generation (2008: 55%; 2018: 32%), and enzyme-inducing ASMs (2008: 44%; 2018: 24%) each decreased over time as a proportion of pill days. The number of brand pill days per person-year initially decreased (e.g., 2008: 250; 2009: 121; 2010: 96) but then plateaued (2013-2018: between 66 and 69) given a notable increase in lacosamide pill days per person (2008: 0; 2018: 20). Total brand name costs per year initially decreased 2008-2010 (2008: $150 million; 2010: $72 million) but then increased after 2010 (2018: $256 million). In 2018, brand name ASMs represented 79% of costs despite representing only 14% of pill days, a 1-year pill supply became 277% more expensive for brand name medications but 42% less expensive for generic medications over time (2008: brand ∼$2,800 vs generic ∼$800; 2018: brand ∼$10,700 vs generic ∼$460), and many common brand name ASMs cost approximately 10-fold more per pill day than their generic equivalents.

DISCUSSION

First-generation and enzyme-inducing ASMs waned from 2008 to 2018. Although brand name ASMs initially waned translating into lower costs and potentially higher value care, after 2010, brand name costs markedly increased because of increasing use of lacosamide plus a 277% increase in per-pill cost of brand name ASMs. Brand name ASMs represented a minority of prescriptions, but the majority of costs.

Serum lipidomic determinants of human diabetic neuropathy in type 2 diabetes

OBJECTIVE

The serum lipidomic profile associated with neuropathy in type 2 diabetes is not well understood. Obesity and dyslipidemia are known neuropathy risk factors, suggesting lipid profiles early during type 2 diabetes may identify individuals who develop neuropathy later in the disease course. This retrospective cohort study examined lipidomic profiles 10 years prior to type 2 diabetic neuropathy assessment.

METHODS

Participants comprised members of the Gila River Indian community with type 2 diabetes (n = 69) with available stored serum samples and neuropathy assessment 10 years later using the combined Michigan Neuropathy Screening Instrument (MNSI) examination and questionnaire scores. A combined MNSI index was calculated from examination and questionnaire scores. Serum lipids (435 species from 18 classes) were quantified by mass spectrometry.

RESULTS

The cohort included 17 males and 52 females with a mean age of 45 years (SD = 9 years). Participants were stratified as with (high MNSI index score > 2.5407) versus without neuropathy (low MNSI index score ≤ 2.5407). Significantly decreased medium-chain acylcarnitines and increased total free fatty acids, independent of chain length and saturation, in serum at baseline associated with incident peripheral neuropathy at follow-up, that is, participants had high MNSI index scores, independent of covariates. Participants with neuropathy also had decreased phosphatidylcholines and increased lysophosphatidylcholines at baseline, independent of chain length and saturation. The abundance of other lipid classes did not differ significantly by neuropathy status.

INTERPRETATION

Abundance differences in circulating acylcarnitines, free fatty acids, phosphatidylcholines, and lysophosphatidylcholines 10 years prior to neuropathy assessment are associated with neuropathy status in type 2 diabetes.

Classification of painful or painless diabetic peripheral neuropathy and identification of the most powerful predictors using machine learning models in large cross-sectional cohorts

BACKGROUND

To improve the treatment of painful Diabetic Peripheral Neuropathy (DPN) and associated co-morbidities, a better understanding of the pathophysiology and risk factors for painful DPN is required. Using harmonised cohorts (N = 1230) we have built models that classify painful versus painless DPN using quality of life (EQ5D), lifestyle (smoking, alcohol consumption), demographics (age, gender), personality and psychology traits (anxiety, depression, personality traits), biochemical (HbA1c) and clinical variables (BMI, hospital stay and trauma at young age) as predictors.

METHODS

The Random Forest, Adaptive Regression Splines and Naive Bayes machine learning models were trained for classifying painful/painless DPN. Their performance was estimated using cross-validation in large cross-sectional cohorts (N = 935) and externally validated in a large population-based cohort (N = 295). Variables were ranked for importance using model specific metrics and marginal effects of predictors were aggregated and assessed at the global level. Model selection was carried out using the Mathews Correlation Coefficient (MCC) and model performance was quantified in the validation set using MCC, the area under the precision/recall curve (AUPRC) and accuracy.

RESULTS

Random Forest (MCC = 0.28, AUPRC = 0.76) and Adaptive Regression Splines (MCC = 0.29, AUPRC = 0.77) were the best performing models and showed the smallest reduction in performance between the training and validation dataset. EQ5D index, the 10-item personality dimensions, HbA1c, Depression and Anxiety t-scores, age and Body Mass Index were consistently amongst the most powerful predictors in classifying painful vs painless DPN.

CONCLUSIONS

Machine learning models trained on large cross-sectional cohorts were able to accurately classify painful or painless DPN on an independent population-based dataset. Painful DPN is associated with more depression, anxiety and certain personality traits. It is also associated with poorer self-reported quality of life, younger age, poor glucose control and high Body Mass Index (BMI). The models showed good performance in realistic conditions in the presence of missing values and noisy datasets. These models can be used either in the clinical context to assist patient stratification based on the risk of painful DPN or return broad risk categories based on user input. Model's performance and calibration suggest that in both cases they could potentially improve diagnosis and outcomes by changing modifiable factors like BMI and HbA1c control and institute earlier preventive or supportive measures like psychological interventions.

Plasma Metabolomics and Lipidomics Differentiate Obese Individuals by Peripheral Neuropathy Status

CONTEXT

Peripheral neuropathy (PN) is a frequent prediabetes and type 2 diabetes (T2D) complication. Multiple clinical studies reveal that obesity and dyslipidemia can also drive PN progression, independent of glycemia, suggesting a complex interplay of specific metabolite and/or lipid species may underlie PN.

OBJECTIVE

This work aimed to identify the plasma metabolomics and lipidomics signature that underlies PN in an observational study of a sample of individuals with average class 3 obesity.

METHODS

We performed plasma global metabolomics and targeted lipidomics on obese participants with (n = 44) and without PN (n = 44), matched for glycemic status, vs lean nonneuropathic controls (n = 43). We analyzed data by Wilcoxon, logistic regression, partial least squares-discriminant analysis, and group-lasso to identify differential metabolites and lipids by obesity and PN status. We also conducted subanalysis by prediabetes and T2D status.

RESULTS

Lean vs obese comparisons, regardless of PN status, identified the most significant differences in gamma-glutamyl and branched-chain amino acid metabolism from metabolomics analysis and triacylglycerols from lipidomics. Stratification by PN status within obese individuals identified differences in polyamine, purine biosynthesis, and benzoate metabolism. Lipidomics found diacylglycerols as the most significant subpathway distinguishing obese individuals by PN status, with additional contributions from phosphatidylcholines, sphingomyelins, ceramides, and dihydroceramides. Stratifying the obese group by glycemic status did not affect discrimination by PN status.

CONCLUSION

Obesity may be as strong a PN driver as prediabetes or T2D in a sample of individuals with average class 3 obesity, at least by plasma metabolomics and lipidomics profile. Metabolic and complex lipid pathways can differentiate obese individuals with and without PN, independent of glycemic status.

Oral and Topical Treatment of Painful Diabetic Polyneuropathy: Practice Guideline Update Summary: Report of the AAN Guideline Subcommittee

OBJECTIVE

To update the 2011 American Academy of Neurology (AAN) guideline on the treatment of painful diabetic neuropathy (PDN) with a focus on topical and oral medications and medical class effects.

METHODS

The authors systematically searched the literature from January 2008 to April 2020 using a structured review process to classify the evidence and develop practice recommendations using the AAN 2017 Clinical Practice Guideline Process Manual.

RESULTS

Gabapentinoids (standardized mean difference [SMD] 0.44; 95% confidence interval [CI], 0.21-0.67), serotonin-norepinephrine reuptake inhibitors (SNRIs) (SMD 0.47; 95% CI, 0.34-0.60), sodium channel blockers (SMD 0.56; 95% CI, 0.25-0.87), and SNRI/opioid dual mechanism agents (SMD 0.62; 95% CI, 0.38-0.86) all have comparable effect sizes just above or just below our cutoff for a medium effect size (SMD 0.5). Tricyclic antidepressants (TCAs) (SMD 0.95; 95% CI, 0.15-1.8) have a large effect size, but this result is tempered by a low confidence in the estimate.

RECOMMENDATIONS SUMMARY

Clinicians should assess patients with diabetes for PDN (Level B) and those with PDN for concurrent mood and sleep disorders (Level B). In patients with PDN, clinicians should offer TCAs, SNRIs, gabapentinoids, and/or sodium channel blockers to reduce pain (Level B) and consider factors other than efficacy (Level B). Clinicians should offer patients a trial of medication from a different effective class when they do not achieve meaningful improvement or experience significant adverse effects with the initial therapeutic class (Level B) and not use opioids for the treatment of PDN (Level B).

Neuropsychological Outcomes in Individuals With Type 1 and Type 2 Diabetes

OBJECTIVE

To determine the prevalence of neuropsychological outcomes in individuals with type 1 diabetes compared to individuals with type 2 diabetes or without diabetes, and to evaluate the association of diabetes status and microvascular/macrovascular complications with neuropsychological outcomes.

PATIENTS AND METHODS

We used a nationally representative healthcare claims database of privately insured individuals (1/1/2001-12/31/2018) to identify individuals with type 1 diabetes. Propensity score matching was used as a quasi-randomization technique to match type 1 diabetes individuals to type 2 diabetes individuals and controls. Diabetes status, microvascular/macrovascular complications (retinopathy, neuropathy, nephropathy, stroke, myocardial infarction, peripheral vascular disease, amputations), and neuropsychological outcomes (mental health, cognitive, chronic pain, addiction, sleep disorders) were defined using ICD-9/10 codes. Logistic regression determined associations between diabetes status, microvascular/macrovascular complications, and neuropsychological outcomes.

RESULTS

We identified 184,765 type 1 diabetes individuals matched to 524,602 type 2 diabetes individuals and 522,768 controls. With the exception of cognitive disorders, type 2 diabetes individuals had the highest prevalence of neuropsychological outcomes, followed by type 1 diabetes, and controls. After adjusting for the presence of microvascular/macrovascular complications, type 1 diabetes was not significantly associated with a higher risk of neuropsychological outcomes; however, type 2 diabetes remained associated with mental health, cognitive, and sleep disorders. The presence of microvascular/macrovascular complications was independently associated with each neuropsychological outcome regardless of diabetes status.

CONCLUSION

Microvascular/macrovascular complications are associated with a high risk of neuropsychological outcomes regardless of diabetes status. Therefore, preventing microvascular and macrovascular complications will likely help reduce the likelihood of neuropsychological outcomes either as the result of similar pathophysiologic processes or by preventing the direct and indirect consequences of these complications. For individuals with type 2 diabetes, risk factors beyond complications (such as obesity) likely contribute to neuropsychological outcomes.

Headache neuroimaging: A survey of current practice, barriers, and facilitators to optimal use

OBJECTIVE

The objective of this study was to understand current practice, clinician understanding, attitudes, barriers, and facilitators to optimal headache neuroimaging practices.

BACKGROUND

Headaches are common in adults, and neuroimaging for these patients is common, costly, and increasing. Although guidelines recommend against routine headache neuroimaging in low-risk scenarios, guideline-discordant neuroimaging is still frequently performed.

METHODS

We administered a 60-item survey to headache clinicians at the Veterans Affairs health system to assess clinician understanding and attitudes on headache neuroimaging and to determine neuroimaging practice patterns for three scenarios describing hypothetical patients with headaches. Descriptive statistics were used to summarize responses, stratified by clinician type (physicians or advanced practice clinicians [APCs]) and specialty (neurology or primary care).

RESULTS

The survey was successfully completed by 431 of 1426 clinicians (30.2% response rate). Overall, 317 of 429 (73.9%) believed neuroimaging was overused for patients with headaches. However, clinicians would utilize neuroimaging a mean (SD) 30.9% (31.7) of the time in a low-risk scenario without red flags, and a mean 67.1% (31.9) of the time in the presence of minor red flags. Clinicians had stronger beliefs in the potential benefits (268/429, 62.5%) of neuroimaging compared to harms (181/429, 42.2%) and more clinicians were bothered by harms stemming from the omission of neuroimaging (377/426, 88.5%) compared to commission (329/424, 77.6%). Additionally, APCs utilized neuroimaging more frequently than physicians and were more receptive to potential interventions to improve neuroimaging utilization.

CONCLUSIONS

Although a majority of clinicians believed neuroimaging was overused for patients with headaches, many would utilize neuroimaging in low-risk scenarios with a small probability of changing management. Future studies are needed to define the role of currently used red flags given their importance in neuroimaging decisions. Importantly, APCs may be an ideal target for future optimization efforts.

Dietary weight loss in people with severe obesity stabilizes neuropathy and improves symptomatology

OBJECTIVE

The aim of this study was to determine the effect of dietary weight loss on neuropathy outcomes in people with severe obesity.

METHODS

A prospective cohort study of participants attending a medical weight-management program was followed. Weight loss was achieved with meal replacement of 800 kcal/d for 12 weeks and then transitioning to 1,200 to 1,500 kcal/d. The coprimary outcomes were changes in intraepidermal nerve fiber density (IENFD) at the distal leg and proximal thigh. Secondary outcomes included nerve conduction studies, Michigan Neuropathy Screening Instrument questionnaire and exam, Quality of Life in Neurological Disorders, and quantitative sensory testing.

RESULTS

Among 131 baseline participants, 72 (mean [SD] age: 50.1 [10.5] years, 51.4% female) completed 2 years of follow-up. Participants lost 12.4 (11.8) kg. All metabolic syndrome components improved with the exception of blood pressure. IENFD in the distal leg (0.4 [3.3], p = 0.29), and proximal thigh (0.3 [6.3], p = 0.74) did not significantly change. Improvements were observed on the Michigan Neuropathy Screening Instrument questionnaire, two Quality of Life in Neurological Disorders subdomains, and quantitative sensory testing cold threshold.

CONCLUSIONS

Dietary weight loss was associated with improvements in all metabolic parameters except blood pressure, and both IENFD outcomes remained stable after 2 years. Given that natural history studies reveal decreases in IENFD over time, dietary weight loss may halt this progression, but randomized controlled trials are needed.

Comparison of the United Kingdom and United States approaches to approval of new neuromuscular therapies

Many novel therapies are now available for rare neuromuscular conditions that were previously untreatable. Hereditary transthyretin amyloidosis and spinal muscular atrophy are two examples of diseases with new medications that have transformed our field. The United States and the United Kingdom have taken disparate approaches to the approval and coverage of medications, despite both providing incentives to develop therapies targeting rare diseases. The US requires less evidence for approval when compared with medications for common diseases and does not have a mechanism to ensure or even encourage cost-effectiveness. The Institute of Clinical and Economic Review provides in-depth cost-effectiveness analyses in the US, but does not have the authority to negotiate drug costs. In contrast, the UK has maintained a similar scientific threshold for approval of all therapies, while requiring negotiation with National Institute for Health and Care Excellence to ensure that medications are cost-effective for rare diseases. These differences have led to approval of medications for rare diseases in the US that have less evidence than required for common diseases. Importantly, these medications have not been approved in the UK. Even when medications meet traditional scientific thresholds, they uniformly arrive with high list prices in the US, whereas they are available at cost-effective prices in the UK. The main downsides to the UK approach are that cost-effective medications are often available months later than in the US, and some medications remain unavailable.

The determinants of complication trajectories in American Indians with type 2 diabetes

BACKGROUNDWe aimed to determine whether metabolic syndrome (MetS) affects longitudinal trajectories of diabetic complications, including neuropathy, cardiovascular autonomic neuropathy (CAN), and kidney disease in American Indians with type 2 diabetes.METHODSWe performed a prospective study where participants underwent annual metabolic phenotyping and outcome measurements. The updated National Cholesterol Education Program criteria were used to define MetS and its individual components, using BMI instead of waist circumference. Neuropathy was defined using the Michigan Neuropathy Screening Instrument index, CAN with the expiration/inspiration ratio, and kidney disease with glomerular filtration rate. Mixed-effects models were used to evaluate associations between MetS and these outcomes.RESULTSWe enrolled 141 participants: 73.1% female, a mean (±SD) age of 49.8 (12.3), and a diabetes duration of 19.6 years (9.7 years) who were followed for a mean of 3.1 years (1.7 years). MetS components were stable during follow-up except for declining obesity and cholesterol. Neuropathy (point estimate [PE]: 0.30, 95% CI: 0.24, 0.35) and kidney disease (PE: -14.2, 95% CI: -16.8, -11.4) worsened over time, but CAN did not (PE: -0.002, 95% CI: -0.006, 0.002). We found a significant interaction between the number of MetS components and time for neuropathy (PE: 0.05, 95% CI: 0.01-0.10) but not CAN (PE: -0.003, 95% CI: -0.007, 0.001) or kidney disease (PE: -0.69, 95% CI: -3.16, 1.76). Systolic blood pressure (SBP, unit = 10 mmHg) was associated with each complication: neuropathy (PE: 0.23, 95% CI: 0.07, 0.39), CAN (PE: -0.02, 95% CI: -0.03, -0.02), and kidney disease (PE: -10.2, 95% CI: -15.4, -5.1).CONCLUSIONIn participants with longstanding diabetes, neuropathy and kidney disease worsened during follow-up, despite stable to improving MetS components, suggesting that early metabolic intervention is necessary to prevent complications in such patients. Additionally, the number of MetS components was associated with an increased rate of neuropathy progression, and SBP was associated with each complication.FUNDINGThe following are funding sources: NIH T32NS0007222, NIH R24DK082841, NIH R21NS102924, NIH R01DK115687, the Intramural Program of the NIDDK, the NeuroNetwork for Emerging Therapies, the Robert and Katherine Jacobs Environmental Health Initiative, the Robert E. Nederlander Sr. Program for Alzheimer's Research, and the Sinai Medical Staff Foundation.TRIAL REGISTRATIONClinicalTrials.gov, NCT00340678.

Plasma lipid metabolites associate with diabetic polyneuropathy in a cohort with type 2 diabetes

Objective

The global rise in type 2 diabetes is associated with a concomitant increase in diabetic complications. Diabetic polyneuropathy is the most frequent type 2 diabetes complication and is associated with poor outcomes. The metabolic syndrome has emerged as a major risk factor for diabetic polyneuropathy; however, the metabolites associated with the metabolic syndrome that correlate with diabetic polyneuropathy are unknown.

Methods

We conducted a global metabolomics analysis on plasma samples from a subcohort of participants from the Danish arm of Anglo‐Danish‐Dutch study of Intensive Treatment of Diabetes in Primary Care (ADDITION‐Denmark) with and without diabetic polyneuropathy versus lean control participants.

Results

Compared to lean controls, type 2 diabetes participants had significantly higher HbA1c (p = 0.0028), BMI (p = 0.0004), and waist circumference (p = 0.0001), but lower total cholesterol (p = 0.0001). Out of 991 total metabolites, we identified 15 plasma metabolites that differed in type 2 diabetes participants by diabetic polyneuropathy status, including metabolites belonging to energy, lipid, and xenobiotic pathways, among others. Additionally, these metabolites correlated with alterations in plasma lipid metabolites in type 2 diabetes participants based on neuropathy status. Further evaluating all plasma lipid metabolites identified a shift in abundance, chain length, and saturation of free fatty acids in type 2 diabetes participants. Importantly, the presence of diabetic polyneuropathy impacted the abundance of plasma complex lipids, including acylcarnitines and sphingolipids.

Interpretation

Our explorative study suggests that diabetic polyneuropathy in type 2 diabetes is associated with novel alterations in plasma metabolites related to lipid metabolism.

Primary care providers perform more neurologic visits than neurologists among Medicare beneficiaries

RATIONALE, AIMS AND OBJECTIVES

Little is known about which medical providers, other than neurologists, are involved in the care of neurologic conditions. We aimed to describe the current distribution of outpatient neurologic care by provider type.

METHODS

We conducted a restrospective, cross-sectional analysis using a 20% national sample claims database that contains information on medical care utilizations from adult Fee-for-Service Medicare beneficiaries in 2015. We identified patient visits for evaluation and management services for common neurologic conditions and by medical provider type. The main outcome was the proportion of visits for neurologic conditions by medical provider type, both in aggregate and across neurologic conditions.

RESULTS

40% of neurologic visits were performed by primary care providers (PCPs) and 17.5% by neurologists. The most common neurologic conditions were back pain (49.3%), sleep disorders (8.0%), chronic pain/abnormality of gait (6.4%), peripheral neuropathy (5.9%), and stroke (5.5%). Neurologists cared for a large proportion of visits for Parkinson's disease (75.6% vs 20.8%), epilepsy (70.9% vs 26.6%), multiple sclerosis (63.9% vs 26.2%), other central NS disorders (54.2% vs 24.9%), and tremor/RLS/ALS (54.0% vs 31.2%) compared to PCPs. PCPs provided a greater proportion of visits for dizziness/vertigo (57.8% vs 9.3%) and headache/migraine (50.4% vs 35.0%) compared to neurologists.

CONCLUSIONS

PCPs perform more neurologic visits than neurologists. With the anticipated increased demand for neurologic care, strategies to optimize neurologic care delivery could consider expanding access to neurologists as well as supporting PCP care for neurologic conditions.

Altered plasma serine and 1-deoxydihydroceramide profiles are associated with diabetic neuropathy in type 2 diabetes and obesity

Recent studies suggest that the accumulation of atypical, 1-deoxysphingolipids that lack the C1 hydroxyl group may be associated with diabetic neuropathy (DN). We hypothesized that specific plasma 1-deoxysphingolipids associate with DN severity, and that alterations in plasma serine and alanine associate with 1-deoxysphingolipid elevation in patients with type 2 diabetes (T2D). We examined individual 1-deoxysphingolipid species using LC/MS/MS in plasma samples from 75 individuals including lean controls (LC, n = 19), those with obesity (n = 19), obesity with T2D without DN (ob/T2D, n = 18), and obesity with T2D with DN (Ob/T2D/DN, n = 19). We observed a step wise increase in 1-deoxydihydroceramides across these four groups (spearman correlation coefficient r = 0.41, p = 0.0002). Mean total concentrations of 1-deoxydihydroceramides, and most individual 1-deoxydihydroceramide species, were higher in ob/T2D/DN versus LC group (8.939 vs. 5.195 pmol/100 μL for total 1-deoxydihydroceramides p = 0.005). No significant differences in 1-deoxydihydroceramides were observed between the ob/T2D and ob/T2D/DN groups. l-alanine was higher and l-serine lower in ob/T2D/DN versus LC groups (326.2 vs. 248.0 μM, p = 0.0086 and 70.2 vs. 89.8 μM, p = 0.0110), consistent with a potential contribution of these changes to the observed 1-deoxysphingolipids profiles. 1-deoxydihydroceramides correlated inversely with leg intraepidermal nerve fiber density (CC -0.40, p = 0.003). These findings indicate that 1-deoxydihydroceramides may be important biomarkers and/or mediators of DN.

Patients who meet electrodiagnostic criteria for CIDP rarely present with a sensory predominant DSP phenotype

INTRODUCTION

It is unknown how often patients with electrodiagnostic evidence of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), a potentially treatable condition, present with a distal symmetric polyneuropathy (DSP) phenotype.

METHODS

We reviewed the records of patients who presented to our electrodiagnostic laboratory between January 1, 2011, to December 31, 2019, and fulfilled electrodiagnostic criteria for CIDP to identify those who presented with a sensory predominant DSP phenotype.

RESULTS

One hundred sixty-two patients had a chronic acquired demyelinating neuropathy, of whom 138 met criteria for typical or atypical CIDP. Nine of these patients presented with a sensory predominant DSP phenotype, among whom six were eventually diagnosed with distal acquired demyelinating symmetric (DADS) neuropathy; one with Polyneuropathy, Organomegaly, Endocrinopathy, Monoclonal protein, Skin changes (POEMS) syndrome; and two with idiopathic DSP. The prevalence of acquired chronic demyelinating neuropathies among all patients presenting with a DSP phenotype was estimated to be 0.34%.

DISCUSSION

Patients who meet electrodiagnostic criteria for CIDP rarely present with a sensory predominant DSP phenotype, and electrodiagnostic testing rarely identifies treatable demyelinating neuropathies in patients who present with a DSP phenotype.

Painful and non-painful diabetic neuropathy, diagnostic challenges and implications for future management

Peripheral neuropathy is one of the most common complications of both type 1 and type 2 diabetes. Up to half of patients with diabetes develop neuropathy during the course of their disease, which is accompanied by neuropathic pain in 30-40% of cases. Peripheral nerve injury in diabetes can manifest as progressive distal symmetric polyneuropathy, autonomic neuropathy, radiculo-plexopathies, and mononeuropathies. The most common diabetic neuropathy is distal symmetric polyneuropathy, which we will refer to as DN, with its characteristic glove and stocking like presentation of distal sensory or motor function loss. DN or its painful counterpart, painful DN, are associated with increased mortality and morbidity; thus, early recognition and preventive measures are essential. Nevertheless, it is not easy to diagnose DN or painful DN, particularly in patients with early and mild neuropathy, and there is currently no single established diagnostic gold standard. The most common diagnostic approach in research is a hierarchical system, which combines symptoms, signs, and a series of confirmatory tests. The general lack of long-term prospective studies has limited the evaluation of the sensitivity and specificity of new morphometric and neurophysiological techniques. Thus, the best paradigm for screening DN and painful DN both in research and in clinical practice remains uncertain. Herein, we review the diagnostic challenges from both clinical and research perspectives and their implications for managing patients with DN. There is no established DN treatment, apart from improved glycaemic control, which is more effective in type 1 than in type 2 diabetes, and only symptomatic management is available for painful DN. Currently, less than one-third of patients with painful DN derive sufficient pain relief with existing pharmacotherapies. A more precise and distinct sensory profile from patients with DN and painful DN may help identify responsive patients to one treatment versus another. Detailed sensory profiles will lead to tailored treatment for patient subgroups with painful DN by matching to novel or established DN pathomechanisms and also for improved clinical trials stratification. Large randomized clinical trials are needed to identify the interventions, i.e. pharmacological, physical, cognitive, educational, etc., which lead to the best therapeutic outcomes.

Executive Functioning in Extreme Obesity: Contributions from Metabolic Status, Medical Comorbidities, and Psychiatric Factors

PURPOSE

Extreme obesity has been associated with cognitive deficits across the lifespan and may be a risk factor for dementia in later life. However, the relationship between obesity and domain-specific cognitive deficits is complicated by a body of literature that often fails to adequately account for medical and psychiatric conditions frequently co-occurring with extreme obesity.

MATERIALS AND METHODS

The present study included a cross-sectional evaluation of adults with extreme obesity (n=117) compared to lean control (n=46) participants on a brief cognitive battery using the NIH Toolbox and Rey Auditory Verbal Learning Test. Specifically, this study evaluated measures of executive functioning, attention, processing speed, learning, and memory while accounting for many common obesity-related medical and psychiatric comorbidities with known cognitive effects.

RESULTS

Results revealed group differences with lower performances on measures of executive functioning, processing speed, and learning (ps<0.01) for participants with obesity. Reduced executive functioning was associated with abdominal obesity and medication use (ps<0.01) and together contributed significantly to overall modeling of cognition in individuals with obesity.

CONCLUSION

Individuals with extreme obesity in this sample showed lower cognitive performance on measures of executive functioning, processing speed, and learning compared to lean controls. Abdominal obesity was associated with executive functioning deficits independent of many common medical and psychiatric factors.

Diabetic neuropathy in children and youth: New and emerging risk factors

Pediatric neuropathy attributed to metabolic dysfunction is a well-known complication in children and youth with type 1 diabetes. Moreover, the rise of obesity and in particular of type 2 diabetes may cause an uptick in pediatric neuropathy incidence. However, despite the anticipated increase in neuropathy incidence, pathogenic insights and strategies to prevent or manage neuropathy in the setting of diabetes and obesity in children and youth remain unknown. Data from adult studies and available youth cohort studies are providing an initial understanding of potential diagnostic, management, and preventative measures in early life. This review discusses the current state of knowledge emanating from these efforts, with particular emphasis on the prevalence, clinical presentation, diagnostic approaches and considerations, and risk factors of neuropathy in type 1 and type 2 diabetes in children and youth. Also highlighted are current management strategies and recommendations for neuropathy in children and youth with diabetes. This knowledge, along with continued and sustained emphasis on identifying and eliminating modifiable risk factors, completing randomized controlled trials to assess effectiveness of strategies like weight loss and exercise, and enhancing awareness to support early detection and prevention, are pertinent to addressing the rising incidence of neuropathy associated with diabetes and obesity in children and youth.

Chemotherapy-induced peripheral neuropathy detection via smartphone app: a cross-sectional pilot study (Preprint)

Background

Severe chemotherapy-induced peripheral neuropathy (CIPN) can cause long-term dysfunction of the hands and feet, interfere with activities of daily living, and diminish the quality of life. Monitoring to identify CIPN and adjust treatment before it progressing to a life-altering severity relies on patients self-reporting subjective symptoms to their clinical team. Objective assessment is not a standard component of CIPN monitoring due to the requirement for specially trained health care professionals and equipment. Smartphone apps have the potential to conveniently collect both subjective and objective CIPN data directly from patients, which could improve CIPN monitoring.

Objective

The objective of this cross-sectional pilot study was to assess the feasibility of functional CIPN assessment via a smartphone app in patients with cancer that have received neurotoxic chemotherapy.

Methods

A total of 26 patients who had completed neurotoxic chemotherapy were enrolled and classified as CIPN cases (n=17) or controls (n=9) based on self-report symptoms. All participants completed CIPN assessments within the NeuroDetect app a single time, including patient-reported surveys (CIPN20 [European Organization for Research and Treatment of Cancer Quality of Life Questionnaire for Chemotherapy-induced Peripheral Neuropathy 20-item scale] and PRO-CTCAE [Patient-Reported Outcomes version of the Common Terminology Criteria for Adverse Events]) and functional assessments (Gait and Balance and 9-Hole Peg Test). Functional assessment data were decomposed into features. The primary analysis was done to identify features indicative of the difference between CIPN cases and controls using partial least squares analyses. Exploratory analyses were performed to test if any features were associated with specific symptom subtypes or patient-reported survey scores. Patient interviews were also conducted to understand the challenges they experienced with the app.

Results

Comparisons between CIPN cases and controls indicate that CIPN cases had shorter step length (P=.007), unique swaying acceleration patterns during a walking task, and shorter hand moving distance in the dominant hands during a manual dexterity task (variable importance in projection scores ≥2). Exploratory analyses showed similar signatures associated with symptoms subtypes, CIPN20, and PRO-CTCAE. The interview results showed that some patients had difficulties due to technical issues, which indicated a need for additional training or oversight during the initial app download.

Conclusions

Our results supported the feasibility of remote CIPN assessment via a smartphone app and suggested that functional assessments may indicate CIPN manifestations in the hands and feet. Additional work is needed to determine which functional assessments are most indicative of CIPN and could be used for CIPN monitoring within clinical care.

Increasing Out-of-Pocket Costs for Neurologic Care for Privately Insured Patients

OBJECTIVE

To measure the out-of-pocket (OOP) costs of evaluation and management (E/M) services and common diagnostic testing for neurology patients.

METHODS

Using a large, privately insured health care claims database, we identified patients with a neurologic visit or diagnostic test from 2001 to 2016 and assessed inflation-adjusted OOP costs for E/M visits, neuroimaging, and neurophysiologic testing. For each diagnostic service each year, we estimated the proportion of patients with OOP costs, the mean OOP cost, and the proportion of the total service cost paid OOP. We modeled OOP cost as a function of patient and insurance factors.

RESULTS

We identified 3,724,342 patients. The most frequent neurologic services were E/M visits (78.5%), EMG/nerve conduction studies (NCS) (7.7%), MRIs (5.3%), and EEGs (4.5%). Annually, 86.5%-95.2% of patients paid OOP costs for E/M visits and 23.1%-69.5% for diagnostic tests. For patients paying any OOP cost, the mean OOP cost increased over time, most substantially for EEG, MRI, and E/M. OOP costs varied considerably; for an MRI in 2016, the 50th percentile paid $103.10 and the 95th percentile paid $875.40. The proportion of total service cost paid OOP increased. High deductible health plan (HDHP) enrollment was associated with higher OOP costs for MRI, EMG/NCS, and EEG.

CONCLUSION

An increasing number of patients pay OOP for neurologic diagnostic services. These costs are rising and vary greatly across patients and tests. The cost sharing burden is particularly high for the growing population with HDHPs. In this setting, neurologic evaluation might result in financial hardship for patients.

Geographic Variation in Neurologist Density and Neurologic Care in the United States

OBJECTIVE

To describe geographic variation in neurologist density, neurologic conditions, and neurologist involvement in neurologic care.

METHODS

We used 20% 2015 Medicare data to summarize variation by Hospital Referral Region (HRR). Neurologic care was defined as office-based evaluation/management visits with a primary diagnosis of a neurologic condition.

RESULTS

Mean density of neurologists varied nearly 4-fold from the lowest to the highest density quintile (9.7 [95% confidence interval (CI) 9.2-10.2] vs 43.1 [95% CI 37.6-48.5] per 100,000 Medicare beneficiaries). The mean prevalence of patients with neurologic conditions did not substantially differ across neurologist density quintile regions (293 vs 311 per 1,000 beneficiaries in the lowest vs highest quintiles, respectively). Of patients with a neurologic condition, 23.5% were seen by a neurologist, ranging from 20.6% in the lowest quintile regions to 27.0% in the highest quintile regions (6.4% absolute difference). Most of the difference comprised dementia, pain, and stroke conditions seen by neurologists. In contrast, very little of the difference comprised Parkinson disease and multiple sclerosis, both of which had a very high proportion (>80%) of neurologist involvement even in the lowest quintile regions.

CONCLUSIONS

The supply of neurologists varies substantially by region, but the prevalence of neurologic conditions does not. As neurologist supply increases, access to neurologist care for certain neurologic conditions (dementia, pain, and stroke) increases much more than for others (Parkinson disease and multiple sclerosis). These data provide insight for policy makers when considering strategies in matching the demand for neurologic care with the appropriate supply of neurologists.

Statin Therapy and Risk of Polyneuropathy in Type 2 Diabetes: A Danish Cohort Study

OBJECTIVE

Statins may reduce the risk of diabetic polyneuropathy (DPN) as a result of lipid-lowering and anti-inflammatory effects, but statins have also been associated with neurotoxicity. We examined whether statin therapy affects the risk of DPN.

RESEARCH DESIGN AND METHODS

We identified all Danish patients with incident type 2 diabetes during 2002-2016. New users initiated statins between 180 days before and 180 days after their first diabetes record, while prevalent users had initiated statins before that period. Patients were followed for incident DPN using validated hospital diagnosis codes, starting 180 days after their first diabetes record. Cox proportional hazard analysis was used to compute adjusted hazard ratios (aHRs) for DPN.

RESULTS

The study cohort comprised 59,255 (23%) new users, 75,528 (29%) prevalent users, and 124,842 (48%) nonusers; median follow-up time was 6.2 years (interquartile range 3.4-9.6). The incidence rate of DPN events per 1,000 person-years was similar in new users (4.0 [95% CI 3.8-4.2]), prevalent users (3.8 [3.6-3.9]), and nonusers (3.8 [3.7-4.0]). The aHR for DPN was 1.05 (0.98-1.11) in new users and 0.97 (0.91-1.04) in prevalent users compared with statin nonusers. New users had a slightly increased DPN risk during the first year (1.31 [1.12-1.53]), which vanished after >2 years of follow-up. Findings were similar in on-treatment and propensity score-matched analyses and with additional adjustment for pretreatment blood lipid levels.

CONCLUSIONS

Statin therapy is unlikely to increase or mitigate DPN risk in patients with type 2 diabetes, although a small acute risk of harm cannot be excluded.

Test Utilization and Value in the Evaluation of Peripheral Neuropathies

Peripheral neuropathies can be classified as typical or atypical. Patients with atypical neuropathy have one or more of the following features: acute/subacute onset, non-length dependence, motor predominance, or asymmetry. This classification is important because it informs the appropriate diagnostic evaluation of this highly prevalent condition. The evaluation of a typical peripheral neuropathy, also known as distal symmetric polyneuropathy, requires a thorough history, neurologic examination, and focused laboratory testing. Electrodiagnostic testing and MRI account for the majority of costs but rarely lead to changes in diagnosis or management. These costs are increasingly being passed on to patients, especially those with high-deductible health plans. In contrast, patients with atypical neuropathy require more extensive testing, including electrodiagnostic tests. These tests are much more likely to lead to the use of disease-modifying therapies in these patients compared to in those with typical peripheral neuropathy. This article describes two cases to illustrate the appropriate diagnostic workup of those with typical or atypical neuropathy.

The metabolic drivers of neuropathy in India

AIMS

To determine the association between the metabolic syndrome (MetS) and neuropathy in Chennai, India.

METHODS

We recruited participants attending the M.V. Hospital for Diabetes. Neuropathy was defined using the Michigan Neuropathy Screening Instrument combined index and MetS was defined using the updated National Cholesterol Education Program criteria. Multivariable logistic regression models were used to assess the associations between individual metabolic components and neuropathy.

RESULTS

Of the 652 participants (42% female and mean (SD) age of 45.5 (9.7)) included in the study, the prevalence of neuropathy was 9.8%. Neuropathy prevalence increased with worsening glycemic status (p < 0.01), but not as the number of MetS components increased (p = 0.12). Among normoglycemic participants, an increasing neuropathy trend was observed as the number of MetS components increased (p = 0.04). Multivariable logistic regression found that diabetes (OR:3.41,1.28-9.11) was associated with neuropathy, but waist circumference was not (OR:1.002,0.88-1.14).

CONCLUSIONS

Similar to previous studies, diabetes was the most important metabolic risk factor for neuropathy in a population from Chennai, India. In contrast to other population-based studies, waist circumference was not associated with neuropathy. Whether the distribution of obesity affects nerves differently in Indian populations requires future studies with more precise anthropometric measures.

Diagnosis and prevalence of diabetic polyneuropathy: a cross-sectional study of Danish patients with type 2 diabetes

BACKGROUND AND PURPOSE

Diabetic polyneuropathy (DPN) is a common complication of diabetes. Using the Toronto criteria for diabetic polyneuropathy and the grading system for neuropathic pain, the performance of neuropathy scales and questionnaires were assessed by comparing them to a clinical gold standard diagnosis of DPN and painful DPN in a cohort of patients with recently diagnosed type 2 diabetes.

METHODS

A questionnaire on neuropathy and pain was sent to a cohort of 5514 Danish type 2 diabetes patients. A sample of 389 patients underwent a detailed clinical examination and completed neuropathy questionnaires and scales.

RESULTS

Of the 389 patients with a median diabetes duration of 5.9 years, 126 had definite DPN (including 53 with painful DPN), 88 had probable DPN and 53 had possible DPN. There were 49 patients with other causes of polyneuropathy, neuropathy symptoms or pain, 10 with subclinical DPN and 63 without DPN. The sensitivity of the Michigan Neuropathy Screening Instrument questionnaire to detect DPN was 25.7% and the specificity 84.6%. The sensitivity of the Toronto Clinical Neuropathy Scoring System, including questionnaire and clinical examination, was 62.9% and the specificity was 74.6%.

CONCLUSIONS

Diabetic polyneuropathy affects approximately one in five Danish patients with recently diagnosed type 2 diabetes but neuropathic pain is not as common as previously reported. Neuropathy scales with clinical examination perform better compared with questionnaires alone, but better scales are needed for future epidemiological studies.

The effects of the Medicare NCS reimbursement policy: Utilization, payments, and patient access

OBJECTIVE

To determine whether the 2013 nerve conduction study (NCS) reimbursement reduction changed Medicare use, payments, and patient access to Medicare physicians by performing a retrospective analysis of Medicare data (2012-2016 fee-for-service data from the CMS Physician and Other Supplier Public Use File).

METHODS

Individual billable services were identified by Healthcare Common Procedure Coding System Current Procedural Terminology and G codes. Medicare use and payments were stratified by specialty and type of service (electrodiagnostic tests, including NCS and EMG, and other neurologic procedures). We also assessed access to Medicare physicians using the annual number of unique beneficiaries receiving initial Evaluation and Management (E/M) services.

RESULTS

We identified 676,113 Medicare providers included in all analysis years from 2012 to 2016 (10,599 neurologists, 5,881 physiatrists, and 659,633 other specialties). Comparing 2016 to 2012 showed that 21.1% fewer neurologists, 28.6% fewer physiatrists, and 69.3% fewer other specialists performed NCS and 3.8% fewer neurologists, 21.7% fewer physiatrists, and 5.6% fewer other specialists performed EMG. For NCS providers in 2012, the mean number of unique Medicare beneficiaries increased for neurologists (1.2%) and physiatrists (4.8%) but decreased for other specialists (-6.5%) by 2016. After the NCS cut, the number of providers performing autonomic and evoked potential testing increased substantially.

CONCLUSIONS

The Medicare NCS reimbursement policy resulted in a larger decrease in NCS providers than in EMG providers. Despite fewer neurologists and physiatrists performing NCS, Medicare access to these physicians for E/M services was not affected. Increased autonomic and evoked potential testing may be an unintended consequence of NCS reimbursement change.