Expenditures in the elderly with peripheral neuropathy: Where should we focus cost-control efforts?

Diagnostic accuracy of the 5.07 monofilament test for diabetes polyneuropathy: influence of age, sex, neuropathic pain and neuropathy severity

INTRODUCTION

There is a need for simple and cheap diagnostic tools for diabetic polyneuropathy (DPN). We aimed to assess the diagnostic accuracy of the 5.07/10 g monofilament test in patients referred to polyneuropathy assessments, as well as to examine how disease severity, age, sex and neuropathic pain (NP) impact diagnostic accuracy.

RESEARCH DESIGN AND METHODS

Five Norwegian university hospitals recruited patients with diabetes aged 18-70 referred to neurological outpatient clinics for polyneuropathy assessments. The 5.07/10 g Semmes-Weinstein monofilament examination (SWME) was validated against the Toronto consensus for diagnosing diabetic neuropathies; the results were stratified by age, sex and NP. Disease severity was graded by a combined nerve conduction study (NCS) Z-score, and logistic regression was applied to assess whether disease severity was a predictor of diagnostic accuracy.

RESULTS

In total, 506 patients were included in the study. Global sensitivity was 0.60 (95% CI 0.55, 0.66), specificity 0.82 (95% CI 0.75, 0.87), positive and negative predictive values were 0.86 (95% CI 0.81, 0.90) and 0.52 (95% CI 0.46, 0.58), respectively, positive and negative likelihood ratios were 3.28 (95% CI 2.37, 4.53) and 0.49 (95% CI 0.42, 0.57), respectively. The SWME was less sensitive in females (0.43), had lower specificity in patients with NP (0.56), and performed worse in patients ≥50 years. NCS-based disease severity did not affect diagnostic accuracy (OR 1.15, 95% CI 0.95, 1.40).

CONCLUSIONS

This multicenter study demonstrates poor diagnostic performance for the 5.07/10 g SWME in patients with diabetes referred to polyneuropathy assessments; it is particularly unsuited for female patients and those with NP. The diagnostic accuracy of the SWME was not influenced by NCS-based disease severity, demonstrating that it does not perform better in patients with later stages of DPN. We do not recommend the use of the 5.07/10 g monofilament in the evaluation of patients with diabetes referred to polyneuropathy assessments.

Advances in Screening, Early Diagnosis and Accurate Staging of Diabetic Neuropathy

The incidence of both type 1 and type 2 diabetes is increasing worldwide. Diabetic peripheral neuropathy (DPN) is among the most distressing and costly of all the chronic complications of diabetes and is a cause of significant disability and poor quality of life. This incurs a significant burden on health care costs and society, especially as these young people enter their peak working and earning capacity at the time when diabetes-related complications most often first occur. DPN is often asymptomatic during the early stages; however, once symptoms and overt deficits have developed, it cannot be reversed. Therefore, early diagnosis and timely intervention are essential to prevent the development and progression of diabetic neuropathy. The diagnosis of DPN, the determination of the global prevalence, and incidence rates of DPN remain challenging. The opinions vary about the effectiveness of the expansion of screenings to enable early diagnosis and treatment initiation before disease onset and progression. Although research has evolved over the years, DPN still represents an enormous burden for clinicians and health systems worldwide due to its difficult diagnosis, high costs related to treatment, and the multidisciplinary approach required for effective management. Therefore, there is an unmet need for reliable surrogate biomarkers to monitor the onset and progression of early neuropathic changes in DPN and facilitate drug discovery. In this review paper, the aim was to assess the currently available tests for DPN's sensitivity and performance.

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.

Utility of electrodiagnostic studies in patients referred with a diagnosis of polyneuropathy

BACKGROUND

Peripheral polyneuropathies (PN) are common neuromuscular conditions. The role of electrodiagnostic study (EDX) in diagnosis of PN is not well-defined.

METHODS

We performed a retrospective chart review of patients referred for EDX evaluation of PN.

RESULTS

Of 162 patients analyzed, 23 had pure peripheral neuropathy (pPN; 14.2%), 29 had peripheral neuropathy and another diagnosis (PN+; 17.9%), 51 had an alternative diagnosis (nonPN; 31.5%), and 59 had normal studies (36.4%). In univariable analysis, age (P < .001) and gender (P = .004) were weakly associated with final diagnosis. In multinomial logistic regression analysis, significant predictors included age (odds ratio [OR] for nonPN/PN+:1.07 per year; 95% confidence interval [CI], 1.03-1.11), gender (OR for PN+:0.2, 95% CI, 0.07-0.61), and diabetes/prediabetes (OR for pPN:3.29; 95% CI, 1.17-9.27).

CONCLUSIONS

These data suggest that EDX commonly yields additional or nonPNs in patients referred with a diagnosis of PN, and although some variables predict electrodiagnosis, none have a large enough effect to suggest poor utility in any subpopulation.

The association of neurologists with headache health care utilization and costs

OBJECTIVE

To determine the association of a neurologist visit with headache health care utilization and costs.

METHODS

Utilizing a large privately insured health care claims database, we identified patients with an incident headache diagnosis (ICD-9 codes 339.xx, 784.0x, 306.81) with at least 5 years follow-up. Patients with a subsequent neurologist visit were matched to controls without a neurologist visit using propensity score matching, accounting for 54 potential confounders and regional variation in neurologist density. Co-primary outcomes were emergency department (ED) visits and hospitalizations for headache. Secondary outcomes were quality measures (abortive, prophylactic, and opioid prescriptions) and costs (total, headache-related, and non-headache-related). Generalized estimating equations assessed differences in longitudinal outcomes between cases and controls.

RESULTS

We identified 28,585 cases and 57,170 controls. ED visits did not differ between cases and controls (p = 0.05). Hospitalizations were more common in cases in year 0-1 (0.2%, 95% confidence interval [CI] 0.2%-0.3% vs 0.01%, 95% CI 0.01%-0.02%; p < 0.01), with minimal differences in subsequent years. Costs (including non-headache-related costs) and high-quality and low-quality medication utilization were higher in cases in the first year and decreased toward control costs in subsequent years with small differences persisting over 5 years. Opioid prescriptions increased over time in both cases and controls.

CONCLUSION

Compared with those without a neurologist, headache patients who visit neurologists had a transient increase in hospitalizations, but the same ED utilization. Confounding by severity is the most likely explanation given the non-headache-related cost trajectory. Claims-based risk adjustment will likely underestimate disease severity of headache patients seen by neurologists.

Vasculitic neuropathy in elderly: A study from a tertiary care university hospital in South India

Objective:

To describe clinical, electrophysiological, and histopathological profile of vasculitic neuropathy in elderly subjects aged 65 years or more.

Design:

Retrospective chart review.

Setting:

Departments of Neurology and Neuropathology, National Institute of Mental Health and Neurosciences, Bengaluru, Karnataka, India.

Patients and Methods:

Elderly subjects, diagnosed vasculitic neuropathy by nerve biopsy over one decade, were studied.

Results:

The cohort consisted of 46 subjects. Symptom duration was 21.54 ± 33.53 months. Onset was chronic in majority (82.6%). Key features included paresthesias (89%), weakness (80%), sensory loss (70%), wasting (63%), and relapsing-remitting course (6.5%). Most Common clinico-electrophysiological patterns were distal symmetrical sensorimotor polyneuropathy - 19, mononeuritis multiplex - 9, and asymmetric sensorimotor neuropathy - 10. Diagnosis of vasculitis was not suspected before biopsy in 31 (67.3%). Nerve biopsy revealed definite vasculitis - 12, probable - 10, and possible - 24. Treatment included immunomodulatory agents (41), symptomatic medications only (9), and antiretroviral therapy (1). Twenty-four patients were followed up for mean period of 6.5 months. Outcome at last follow-up was improved (13), unchanged (8), and worsened (3).

Conclusion:

Vasculitis is an important, treatable cause of neuropathy in elderly. Nerve biopsy should be used judiciously for early diagnosis and appropriate treatment.

Rapid screening for inflammatory neuropathies by standardized clinical criteria

Background

Delay in recognition and treatment of inflammatory neuropathies increases morbidity and mortality. We have developed and standardized 3 clinical screening criteria that rapidly detect inflammatory neuropathies.

Methods

We reviewed all patients with definite large fiber neuropathy in 2 different patient populations: 1 from a private neurology clinic and the other from a tertiary care center. Patients were divided into 2 groups: those with an inflammatory neuropathy and those with a noninflammatory neuropathy. We specifically noted the 3 key neuropathy characteristics: onset, distribution, and associated systemic features (ODS). We studied the sensitivity and specificity of ODS in differentiating between inflammatory and noninflammatory neuropathies.

Results

A total of 206 patients were included: 51 from the private clinic and 155 from the tertiary care center. The sensitivity of using ODS in detecting an inflammatory neuropathy was 96% and the specificity was 85%. The positive predictive value of ODS was 0.8 and negative predictive value was 0.97.

Conclusions

Rapid screening for inflammatory neuropathies by ODS clinical criteria is highly sensitive and has a high negative predictive value for noninflammatory neuropathies. ODS uses simple clinical criteria to rapidly screen for patients with a potentially treatable form of neuropathy and accelerate their diagnostic evaluation.

Classification of evidence

This study provides Class IV evidence that 3 neuropathy characteristics-onset, distribution, and associated systemic features-accurately identify patients with inflammatory neuropathies.

Distal Symmetric Polyneuropathy: A Review

IMPORTANCE

Peripheral neuropathy is a highly prevalent and morbid condition affecting 2% to 7% of the population. Patients frequently experience pain and are at risk of falls, ulcerations, and amputations. We aimed to review recent diagnostic and therapeutic advances in distal symmetric polyneuropathy, the most common subtype of peripheral neuropathy.

OBSERVATIONS

Current evidence supports limited routine laboratory testing in patients with distal symmetric polyneuropathy. Patients without a known cause should undergo a complete blood cell count, comprehensive metabolic panel, vitamin B12 measurement, serum protein electrophoresis with immunofixation, fasting glucose measurement, and glucose tolerance test. The presence of atypical features such as asymmetry, non-length dependence, motor predominance, acute or subacute onset, and prominent autonomic involvement should prompt a consultation with a neurologist or neuromuscular specialist. Electrodiagnostic tests and magnetic resonance imaging of the neuroaxis contribute substantial cost to the diagnostic evaluation, but evidence supporting their use is lacking. Strong evidence supports the use of tricyclic antidepressants, serotonin norepinephrine reuptake inhibitors, and voltage-gated calcium channel ligands in the treatment of neuropathic pain. More intensive glucose control substantially reduces the incidence of distal symmetric polyneuropathy in patients with type 1 diabetes but not in those with type 2 diabetes.

CONCLUSIONS AND RELEVANCE

The opportunity exists to improve guideline-concordant testing in patients with distal symmetric polyneuropathy. Moreover, the role of electrodiagnostic tests needs to be further defined, and interventions to reduce magnetic resonance imaging use in this population are needed. Even though several efficacious medications exist for neuropathic pain treatment, pain is still underrecognized and undertreated. New disease-modifying medications are needed to prevent and treat peripheral neuropathy, particularly in type 2 diabetes.

Role of neurologists and diagnostic tests on the management of distal symmetric polyneuropathy

IMPORTANCE

Distal symmetric polyneuropathy (DSP) is a prevalent condition that results in high costs from diagnostic testing. However, the role of neurologists and diagnostic tests in patient care is unknown.

OBJECTIVE

To determine how often neurologists and diagnostic tests influence the diagnosis and management of DSP in a community setting.

DESIGN, SETTING, AND PARTICIPANTS

In this retrospective cohort study, we used a validated case-capture method (International Classification of Diseases, Ninth Revision screening technique with subsequent medical record abstraction) to identify all patients with a new DSP diagnosis treated by community neurologists in Nueces County, Texas, who met the Toronto Diabetic Neuropathy Expert Group consensus criteria for probable DSP. Using a structured data abstraction process, we recorded diagnostic test results, diagnoses rendered (before and after testing), and subsequent management from April 1, 2010, through March 31, 2011.

MAIN OUTCOMES AND MEASURES

Changes in DSP cause and management after diagnostic testing by neurologists.

RESULTS

We identified 458 patients with DSP followed up for a mean (SD) of 435.3 (44.1) days. Neurologists identified a cause of DSP in 291 patients (63.5%) before their diagnostic testing. Seventy-one patients (15.5%) had a new DSP cause discovered after testing by neurologists. The most common new diagnoses were prediabetes (28 [6.1%]), vitamin B12 deficiency (20 [4.4%]), diabetes mellitus (8 [1.7%]), and thyroid disease (8 [1.7%]). Management changes were common (289 [63.1%]) and usually related to neuropathic pain management (224 [48.9%]). A potential disease-modifying management change was made in 113 patients (24.7%), with the most common changes being diabetes management in 45 (9.8%), treatment with vitamins in 39 (8.5%), diet and exercise in 33 (7.2%), and adjustment of thyroid medications in 10 (2.2%). Electrodiagnostic testing and magnetic resonance imaging of the neuroaxis rarely led to management changes.

CONCLUSIONS AND RELEVANCE

Neurologists diagnosed the cause of DSP in nearly two-thirds of patients before their diagnostic testing. Inexpensive blood tests for diabetes, thyroid dysfunction, and vitamin B12 deficiency allowed neurologists to identify a new cause of DSP in 71 patients (15.5%). In contrast, expensive electrodiagnostic tests and magnetic resonance imaging rarely changed patient care.

The diagnostic utility of Sudoscan for distal symmetric peripheral neuropathy

AIMS

Diagnosis of early distal symmetric polyneuropathy (DSP) is challenging. Nerve conduction studies (NCS) are often normal. Skin biopsy for intraepidermal nerve fiber density (IENFD) has better sensitivity, but is invasive. Sudoscan is a novel technology that measures electrochemical skin conductance (ESC; microSiemens, μS), which is thought to be proportionate to the number of functional sweat glands. This study evaluated Sudoscan's diagnostic utility for DSP.

METHODS

55 patients with suspected DSP (22 with diabetes, 2 prediabetes, 31 idiopathic) and 42 controls underwent the Utah Early Neuropathy Scale (UENS) and Sudoscan. Each was offered skin biopsy. DSP participants underwent quantitative sudomotor axon reflex testing (QSART) and NCS.

RESULTS

Feet and hands ESCs were reduced among DSP participants compared to controls (64±22 vs. 76±14 μS p<0.005, and 58±19 vs. 66±18 μS p<0.04). There was no difference between diabetic and idiopathic DSP. Receiver operating characteristic curve analysis revealed feet ESC and IENFD had similar areas under the curve (0.761 and 0.752). ESC correlated with Sural amplitude (0.337, p<0.02), UENS (-0.388, p<0.004), and MNSI (-0.398, p<0.005).

CONCLUSIONS

Sudoscan is a promising diagnostic test for diabetic and idiopathic DSP, with diagnostic performance similar to IENFD.