Diabetic peripheral neuropathic pain: clinical and quality-of-life issues

Chronic pain with neuropathic characteristics in diabetic patients: a French cross-sectional study

OBJECTIVE

Our aim was to estimate the prevalence of distal chronic pain with neuropathic characteristics in patients with type 1 and type 2 diabetes mellitus and its impact on quality of life, mood, anxiety, sleep and healthcare utilization.

METHODS

In total, 885 patients were screened and 766 diabetic patients (38.7% with type 1 diabetes mellitus, 44.8% women, mean age: 57.2 ± 14.9 years) were enrolled consecutively over a three-month period in this observational study by 85 diabetes specialists working in a hospital department or in private practice. All the patients completed a series of questionnaires for the detection of chronic pain (i.e. daily pain for more than three months) in the lower limbs and assessment of health-related quality of life (Medical Outcomes Short Form 12 scale), sleep disturbances (MOS sleep scale), depression and anxiety (Hospital Anxiety and Depression scale). Patients with chronic pain were also assessed with the 7-item DN4-interview questionnaire, the monofilament test and the Michigan Neuropathy Screening Instrument (MNSI).

RESULTS

The overall prevalence of chronic pain with neuropathic characteristics was 20.3% [95% CI 17.4-23.1]. The MNSI examination score suggested that pain was related to polyneuropathy, in 80.1% of these patients (89.5% of those with bilateral pain). Patients with chronic pain had a poorer quality of life and more sleep disturbances, anxiety and depression than patients without pain and the presence of neuropathic characteristics was predictive of such impairments. Only 38.6% of the patients had received appropriate treatment for neuropathic pain.

CONCLUSIONS

Chronic pain with neuropathic characteristics concerns one in five diabetic patients, has a significant impact on quality of life and is not adequately managed. The close correlation between the DN4 questionnaire and MNSI results suggests that screening tools for neuropathic pain could be used in daily practice for the identification of painful diabetic polyneuropathy.

Painful diabetic polyneuropathy: approach to diagnosis and management

OBJECTIVES

To provide a current overview of the diagnostic work-up and management of painful diabetic polyneuropathy (PDPN).

METHODS

A review covering the literature from 2004 to 2011, which describes the tools designed to diagnose neuropathic pain and assess its severity, including self-administered questionnaires, validated laboratory tests and simple handheld screening devices, and the evidence-based therapeutic approaches to PDPN.

RESULTS

The clinical aspects, pathogenesis, and comorbidities of PDPN, as well as its impact on health related quality of life (HR-QoL), are the main drivers for the management of patients with suspected PDPN. PDPN treatment consists first of all in improving glycemic control and lifestyle intervention. A number of symptomatic pharmacological agents are available for pain control: tricyclic antidepressants and selective serotonin norepinephrine reuptake inhibitors (venlafaxine and duloxetine), α2-delta ligands (gabapentin and pregabalin), opioid analgesics (tramadol and oxycodone), and agents for topical use, such as lidocaine patch and capsaicin cream. With the exception of transcutaneous electrical nerve stimulation, physical treatment is not supported by adequate evidence.

DISCUSSION

As efficacy and tolerability of current therapy for PDPN are not ideal, the need for a better approach in management further exists. Novel compounds should be developed for the treatment of PDPN.

Imaging and quantification of subbasal nerve plexus in healthy volunteers and diabetic patients with or without retinopathy

BACKGROUND

The alterations of subbasal nerve plexus (SBP) innervation and corneal sensation were estimated non-invasively and compared with the values in healthy volunteers. Additionally, this study addressed the relation of SBP changes to the retinal status, glycemic control and diabetes duration.

METHODOLOGY/PRINCIPAL FINDINGS

Eighteen eyes of diabetic patients with peripheral diabetic neuropathy aged 68.8±8.8 years and twenty eyes of healthy volunteers aged 66.3±13.3 yrs. were investigated with in vivo confocal laser-scanning microscopy (CLSM). An adapted algorithm for image analysis was used to quantify the morphological and topological properties of SBP. These properties were correlated to incidence of diabetic retinopathy (DR) and corneal sensation (Cochet-Bonnet esthesiometer). The developed algorithm allows a fully automated analysis of pre-segmented SBP structures. Altogether, 10 parameters were analysed, and all of them revealed significant differences between diabetic patients and healthy volunteers. The nerve fibre density, total fibre length and nerve branches were found to be significantly lower in patients with diabetes than those of control subjects (nerve fibre density 0.006±0.002 vs. 0.020±0.007 mm/mm(2); total fibre length 6223±2419 vs. 19961±6553 µm; nerve branches 25.3±28.6 vs. 141.9±85.7 in healthy volunteers). Also the corneal sensation was significantly lower in diabetic group when compared to controls (43±11 vs. 59±18 mm). There was found no difference in SBP morphology or corneal sensation in the subgroups with (DR) or without (NDR) diabetic retinopathy.

CONCLUSIONS/SIGNIFICANCE

SBP parameters were significantly reduced in diabetic patients, compared to control group. Interestingly, the SBP impairment could be shown even in the diabetic patients without DR. Although automatic adapted image analysis simplifies the evaluation of in vivo CLSM data, image acquisition and quantitative analysis should be optimised for the everyday clinical practice.

Reversal of the Symptoms of Diabetic Neuropathy through Correction of Vitamin D Deficiency in a Type 1 Diabetic Patient

Vitamin D deficiency has been associated with both type 1 and type 2 diabetes as well as both the microvascular and macrovascular complications of diabetes. Vitamin D deficiency has been shown to be more common in diabetic patients who have symptoms of distal symmetrical polyneuropathy. In addition, vitamin D deficiency has been associated with a lower pain threshold which increases when vitamin D deficiency is corrected. Herein, I describe a type 1 diabetic patient with neuropathic symptoms so severe that he could not work and for which he needed narcotics for pain management and whose symptoms improved dramatically with correction of the vitamin D deficiency. To my knowledge, this is the first report of an improvement in severe symptoms of diabetic neuropathy with correction of vitamin D deficiency in a single patient.

H-reflex and clinical examination in the diagnosis of diabetic polyneuropathy

OBJECTIVES

To determine among adult patients with type-2 diabetes mellitus the proportion diagnosed with diabetic polyneuropathy (DPN) by clinical evaluation and by the Hoffmann reflex (H-reflex). In addition, the predictive value of the H-reflex in the diagnosis of DPN was evaluated.

METHODS

Studies were carried out on 150 adult patients referred for neuropathy screening. Diagnostic criteria for DPN were at least two abnormalities in clinical neurophysiological examinations and electrophysiological testing (H-reflex and nerve conduction velocity). Logistic regression analysis was performed to identify unique contributions of study characteristics to positive versus negative outcomes.

RESULTS

H-reflex was absent in 39.3% (59/150) and latency was prolonged in 43.3% (65/150) of patients. Ulnar nerve motor branch nerve conduction showed prolonged latency in 9.3% (14/150) of patients. Logistic regression analysis indicated that the H-reflex was significantly associated with positive outcomes.

CONCLUSION

The H-reflex could have a predictive value in DPN, providing more quantitative information regarding diagnosis than conventional nerve conduction studies.

The size of motoneurons of the gastrocnemius muscle in rats with diabetes

Alterations in the number and size of motoneurons were studied in the medial gastrocnemius (MG) motor nucleus of diabetic rats (12 or 22 weeks after injection of storeptozotocin) and age-matched controls. Each group contained 6 animals. MG motoneurons were retrogradely labeled by dextran-fluorescein and the number and size of cell bodies were examined. Significantly fewer labeled MG motoneurons were found in the 22-week diabetic rats as compared with age-matched control animals. The mean soma diameter of MG motoneurons was significantly smaller in the 12- and 22-week diabetic animals. Furthermore the soma size for 22-week diabetic animals was smaller than for 12-week diabetic animals. The distribution of average soma diameters in the MG nucleus of control animals was bimodal; cells with larger average diameter were presumed to be alpha-motoneurons and those with smaller diameters were presumed to be gamma. Compared to control animals, the number of smaller MG motoneurons was reduced in 12 week diabetic animals. By 22 weeks, diabetic animals had no small MG motoneurons and the size distribution became unimodal. We conclude that there is a significant decrease in the absolute number and size of MG motoneurons in diabetic rats, with the possibility that the decrease occurred predominantly among the smaller gamma-motoneurons.

The Lived Experience of Peripheral Neuropathy after Solid Organ Transplant

Background

The immunosuppressants required after transplant cause peripheral neuropathy with an incidence of 10% to 60%. Peripheral neuropathy adversely affects health-related quality of life in other populations.

Objective

To describe the lived experience of peripheral neuropathy after solid organ transplant.

Design

A qualitative phenomenological study with semistructured interviews. A purposive sample of 7 solid organ transplant recipients with peripheral neuropathy was recruited from 2 transplant clinics at a large Midwest tertiary care center. Interviews were audio taped and transcribed verbatim. Data were analyzed line-byline and coded by using HyperResearch 2.0.

Results

Although participants' experiences were similar to those reported by others with peripheral neuropathy, there were also unique differences. Unique to this population was unexpected onset, rapid escalation of symptoms, lack of provider monitoring, and poor provider response to reported symptoms. Their experience demonstrated that peripheral neuropathy diminished health-related quality of life. Four themes emerged from the data: (1) nothing is supposed to happen after transplant; (2) neuropathy causes me more problems than my heart; (3) maybe there is something that could help; and (4) I've learned to live with certain limitations.

Conclusion

Development of or worsening of peripheral neuropathy after solid organ transplant may decrease health-related quality of life. Follow-up care should include vigilant monitoring for signs of peripheral neuropathy. Providers need to provide early treatment, education, support, empathy, and understanding.

Prevalence and clinical characteristics of diabetic peripheral neuropathy in hospital patients with Type 2 diabetes in Korea

AIMS

Diabetic peripheral neuropathy is a common complication of diabetes. This cross-sectional study investigated the prevalence and clinical characteristics of this neuropathy in patients with Type 2 diabetic mellitus treated at hospitals in Korea.

METHODS

Questionnaires and medical records were used to collect data on 4000 patients with Type 2 diabetes from the diabetes clinics of 40 hospitals throughout Korea. Diabetic peripheral neuropathy was diagnosed based on a review of medical records or using the Michigan Neuropathy Screening Instrument score and monofilament test.

RESULTS

The prevalence of neuropathy was 33.5% (n = 1338). Multivariate analysis revealed that age, female sex, diabetes duration, lower glycated haemoglobin, treatment with oral hypoglycaemic agents or insulin, presence of retinopathy, history of cerebrovascular or peripheral arterial disease, presence of hypertension or dyslipidaemia, and history of foot ulcer were independently associated with diabetic peripheral neuropathy. Of the patients with neuropathy, 69.8% were treated for the condition and only 12.6% were aware of their neuropathy.

CONCLUSION

There was a high prevalence of peripheral neuropathy in patients with Type 2 diabetes in Korea and those patients were far more likely to have complications or co-morbidities. The proper management of diabetic peripheral neuropathy deserves attention from clinicians to ensure better management of diabetes in Korea.

A method for corneal nerves automatic segmentation and morphometric analysis

The segmentation and morphometric analysis of corneal sub-basal nerves, from corneal confocal microscopy images, has gained recently an increased interest. This interest arises from the possibility of using changes in these nerves as the basis of a simple and non-invasive method for early detection and follow-up of peripheral diabetic neuropathy, a major cause of chronic disability in diabetic patients. Here, we propose one method for automatic segmentation and analysis of corneal nerves from images obtained in vivo through corneal confocal microscopy. The method is capable of segmenting corneal nerves, with sensitivity near 90% and a percentage of false recognitions with an average of 5.3%. The nerves tortuosity was calculated and shows statistically significant differences between healthy controls and diabetic individuals, in accordance to what is reported in the literature.

Anti-inflammatory mesenchymal stem cells (MSC2) attenuate symptoms of painful diabetic peripheral neuropathy

Mesenchymal stem cells (MSCs) are very attractive candidates in cell-based strategies that target inflammatory diseases. Preclinical animal studies and many clinical trials have demonstrated that human MSCs can be safely administered and that they modify the inflammatory process in the targeted injured tissue. Our laboratory developed a novel method that optimizes the anti-inflammatory effects of MSCs. We termed the cells prepared by this method MSC2. In this study, we determined the effects of MSC2-based therapies on an inflammation-linked painful diabetic peripheral neuropathy (pDPN) mouse model. Streptozotocin-induced diabetic mice were treated with conventionally prepared MSCs, MSC2, or vehicle at three specific time points. Prior to each treatment, responses to radiant heat (Hargreaves) and mechanical stimuli (von Frey) were measured. Blood serum from each animal was collected at the end of the study to compare levels of inflammatory markers between the treatment groups. We observed that MSC2-treated mice had significant improvement in behavioral assays compared with the vehicle and MSC groups, and moreover these responses did not differ from the observations seen in the healthy wild-type control group. Mice treated with conventional MSCs showed significant improvement in the radiant heat assay, but not in the von Frey test. Additionally, mice treated with MSC2 had decreased serum levels in many proinflammatory cytokines compared with the values measured in the MSC- or vehicle-treated groups. These findings indicate that MSC2-based therapy is a new anti-inflammatory treatment to consider in the management of pDPN.

Evaluation of oxidative stress markers in pathogenesis of diabetic neuropathy

Experimental evidences suggest that hyperglycaemia-induced overproduction of reactive oxygen species and subsequent damage to proteins, lipids and DNA may play a key role in the development of distal symmetric polyneuropathy (DSPN)—the most common complication of diabetes mellitus. The study population consisted of 51 individuals aged 52–82 years classified into 3 groups: 16 patients diagnosed with type 2 diabetes mellitus (T2DM) with DSPN, 16 T2DM patients without DSPN and 19 control subjects without diabetes and neuropathy. The study was conducted to determine the activity of antioxidant enzymes: catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPX) and total antioxidant status (TAS) in the examined groups. An alkaline comet assay was used to determine the extent of DNA damage of oxidized purines as glicosylo-formamidoglicosylase (Fpg) sites, and oxidized pyrimidines as endonuclease III (Nth) sites. A significant decrease of SOD (P < 0.05), GPX (P < 0.05) and nonsignificant decrease of CAT (P > 0.05), and TAS status (P > 0.05) were seen in T2DM patients with neuropathy compared to T2DM patients as well as controls. T2DM patients with or without neuropathy revealed significantly lower (P < 0.05) plasma concentration of nitrous oxide compared to the control subjects. Endogenous level of oxidative DNA damage in T2DM patients with DSPN was significantly higher compared both to the controls and T2DM patients without DSPN (P < 0.001). Moreover, lymphocytes isolated from T2DM patients with DSPN were more susceptible to oxidative DNA lesions induced by hydrogen peroxide than from T2DM patients without DSPN (P < 0.001). Our results confirm hypothesis that oxidative stress may play a substantial role in the development and progression of diabetic distal symmetric polyneuropathy.

Contribution of mitochondria to pain in diabetic neuropathy

Diabetes is a metabolic disease affecting approximately 300 million people worldwide. Neuropathy is one of its frequent complications, and may affect sensory, motor, and autonomic nerves. Its pathophysiology has not fully been elucidated. Several hypotheses have been proposed, and mitochondria have been suggested to play a significant role. This article reviews the mechanisms involved in mitochondrial dysfunction and development of diabetic neuropathy, consisting mainly of oxidative and inflammatory stress, changes in intracellular calcium regulation, apoptotic processes, and changes in mitochondrial structure and function that may lead to development of diabetic neuropathy.

Dosing pattern comparison between duloxetine and pregabalin among patients with diabetic peripheral neuropathic pain

OBJECTIVE

To compare medication dosing patterns of duloxetine and pregabalin among patients with diabetic peripheral neuropathic pain (DPNP).

METHODS

Applying a retrospective cohort study design on a large U.S. healthcare claims database, we examined the dosing patterns of duloxetine and pregabalin among commercially insured patients with DPNP aged 18 to 64 who initiated (a 90-day medication gap) duloxetine or pregabalin therapy in 2006. Selected patients had continuous enrollment during the 12-month pre- and post-index periods. The index mediation was used to classified individuals into the duloxetine or pregabalin cohorts. Initial daily dose, average daily dose over the first post-index year, and average daily dose of the first several prescriptions were estimated and compared across the cohorts.

RESULTS

The study sample included 828 duloxetine and 1934 pregabalin-treated patients with a mean age of 50 years. Cardiovascular diseases, neuropathic pain other than DPNP, osteoarthritis, and diabetic retinopathy were the most common comorbid conditions. The average initial daily doses were 54.3 and 171.8 mg for duloxetine and pregabalin, respectively. The average daily dose over the first post-index year was 55.2 mg for duloxetine and 173.8 mg for pregabalin. The average daily dose for the first 10 duloxetine prescriptions ranged between 54.3 and 61.9 mg, but increased from 171.8 to 264.3 mg for pregabalin.

CONCLUSIONS

The commercially insured patients with DPNP who initiated duloxetine or pregabalin therapy had different dosing patterns. The average daily dose for duloxetine was relatively stable over time, while pregabalin-treated patients had significant dose increase over the 12-month post-index period.

Association between vitamin D and diabetic neuropathy in a nationally representative sample: results from 2001-2004 NHANES

AIMS

To evaluate the association between vitamin D insufficiency and peripheral neuropathy in a nationally representative sample of adults with diagnosed diabetes.

METHODS

Vitamin D concentrations, medical examination variables and questionnaire results from the 2001-2004 National Health and Nutrition Examination Survey were analysed for adults ≥ 40 years old with diagnosed diabetes (unweighted n = 591, weighted n = 8.82 million). Neuropathy was defined as self report of peripheral neuropathy symptoms of painful sensation, tingling, numbness or loss of feeling in hands or feet. Additionally, Semmes-Weinstein monofilament test results were used as an indicator of neuropathy. Insufficient vitamin D was characterized as < 30 ng/ml.

RESULTS

In the weighted population, 81% of adults with diabetes had vitamin D insufficiency. Vitamin D insufficiency was more common among Hispanics (92%) and non-Hispanic black people (98%) than among non-Hispanic white people (76%). Within the 3 months preceding the questionnaire, 50% reported experiencing pain or numbness (paresthesia) in their hands or feet; 37% reported pain or tingling in hands or feet; and 38% reported numbness or loss of feeling in hands or feet. Eight per cent had 4-6 insensate areas on their feet as determined by the Semmes-Weinstein monofilament test. Logistic regressions demonstrate vitamin D insufficiency is associated with the adjusted composite paresthesia measure (odds ratio 2.12; 95% CI 1.17-3.85) and the adjusted numbness measure (odds ratio 2.04; 95% CI 1.18-3.52).

CONCLUSIONS

Vitamin D insufficiency is associated with self-reported peripheral neuropathy symptoms even after adjusting for demographic factors, obesity, co-morbidities, use of medications for neuropathy and diabetes duration and control.

The Central Role of Glia in Pathological Pain and the Potential of Targeting the Cannabinoid 2 Receptor for Pain Relief

Under normal conditions, acute pain processing consists of well-characterized neuronal signaling events. When dysfunctional pain signaling occurs, pathological pain ensues. Glial activation and their released factors participate in the mediation of pathological pain. The use of cannabinoid compounds for pain relief is currently an area of great interest for both basic scientists and physicians. These compounds, bind mainly either the cannabinoid receptor subtype 1 (CB(1)R) or cannabinoid receptor subtype 2 (CB(2)R) and are able to modulate pain. Although cannabinoids were initially only thought to modulate pain via neuronal mechanisms within the central nervous system, strong evidence now supports that CB(2)R cannabinoid compounds are capable of modulating glia, (e.g. astrocytes and microglia) for pain relief. However, the mechanisms underlying cannabinoid receptor-mediated pain relief remain largely unknown. An emerging body of evidence supports that CB(2)R agonist compounds may prove to be powerful novel therapeutic candidates for the treatment of chronic pain.

Neurotrophic activity of DA-9801, a mixture extract of Dioscorea japonica Thunb. and Dioscorea nipponica Makino, in vitro

ETHNOPHARMACOLOGICAL RELEVANCE

Dioscorea japonica Thunb. has been traditionally used to treat polyuria and diabetes in Korea.

AIM OF THE STUDY

We previously report the effects of Dioscorea japonica Thunb. extract on glucose control, NGF induction, and neuroprotection in a rodent diabetic model. Since the most potent fraction, DA-9801, was identified from a mixture of Dioscorea japonica Thunb. (DJ) and Dioscorea nipponica Makino (DN) following bioactivity-guided fractionation, here, we investigated the potential mechanism of the extract activity against diabetic peripheral neuropathy (DPN).

MATERIALS AND METHODS

A 1:3 mixture of DJ and DN was extracted with ethanol (DA-9801) and further fractionated into an ethylacetate-soluble fraction (DA-9801E). Effects of these extracts on neurite outgrowth were measured in PC-12 cells and DRG neurons. Effects on cell viability and TrkA phosphorylation were evaluated in PC-12 cells. NGF induction effect was determined in primary Schwann cells as well as IMS32 cells (immortalized Schwann cells).

RESULTS

No cytotoxicity was observed in PC-12 cells at the concentration below 500 μg/ml of either DA-9801 or DA-9801E. DA-9801 and DA-9801E at 100 μg/ml and 10 μg/ml, respectively, showed a significant effect on neurite outgrowth in PC-12 cells and DRG neurons in the presence of or absence a low concentration of NGF (2 ng/ml). The Trk-A phosphorylation effect of DA9801 was confirmed in PC-12 cells. An NGF induction effect of these extracts was not detected in either IMS-32 cells, or primary Schwann cells.

CONCLUSIONS

The NGF agonistic activity of DA-9801 and DA-9801E was demonstrated, which may contribute to their neuroprotective effect against DPN. Studies of the detailed mechanism of these extracts as well as identification of the active components are warranted for the development of an anti-DPN drug from DJ and DN.

Tapentadol extended-release for treatment of chronic pain: a review

Tapentadol is a centrally acting analgesic with a dual mechanism of action of mu receptor agonism and norepinephrine reuptake inhibition. Tapentadol immediate-release is approved by the US Food and Drug Administration for the management of moderate-to-severe acute pain. It was developed to decrease the intolerability issue associated with opioids. Tapentadol extended-release has a 12-hour duration of effect, and has recently been evaluated for pain in patients with chronic osteoarthritis, low back pain, and pain associated with diabetic peripheral neuropathy. Tapentadol extended-release was found to provide safe and highly effective analgesia for the treatment of chronic pain conditions, including moderate-to-severe chronic osteoarthritis pain and low back pain. Initial trials demonstrating efficacy in neuropathic pain suggest that tapentadol has comparable analgesic effectiveness and better gastrointestinal tolerability than opioid comparators, and demonstrates effectiveness in settings of inflammatory, somatic, and neuropathic pain. Gastrointestinal intolerance and central nervous system effects were the major adverse events noted. Tapentadol will need to be rigorously tested in chronic neuropathic pain, cancer-related pain, and cancer-related neuropathic pain.

Opioid utilization and health-care costs among patients with diabetic peripheral neuropathic pain treated with duloxetine vs. other therapies

OBJECTIVE

This retrospective cohort study assessed subsequent opioid utilization and health-care costs among patients with diabetic peripheral neuropathic pain (DPNP) who initiated duloxetine vs. other standard of care (SOC) treatments.

METHODS

Medical and pharmacy claims were analyzed for commercially-insured individuals aged 18-64. Two study cohorts were constructed from DPNP patients who initiated duloxetine or SOC medications (tricyclic antidepressants, venlafaxine, gabapentin, pregabalin) between March 1, 2005 and December 31, 2005. Initiation was defined as a prior 90-day period without access of the medication. The dispense date of the first initiation was denoted as the index date. Patients with opioids dispensed in the prior 90 days were excluded. Opioid utilization including total days, number of prescriptions filled, and morphine equivalent dosage was assessed for overall, long-acting, and short-acting opioids. Health-care costs and opioid use in the 12-month post-index period were examined via multivariate regression analyses.

RESULTS

Four hundred and ninety-nine DPNP patients (272 duloxetine, 227 SOC) were identified. SOC patients had higher prevalence of comorbidities and pre-index health-care costs than duloxetine patients. Controlling for cross-cohort differences, duloxetine patients were significantly less likely to use any opioids than SOC patients. Also, duloxetine patients had 20 fewer adjusted opioid supply days (largely due to the use of short-acting opioids, P < 0.05) and significantly lower adjusted total costs ($8,088, P < 0.05) and diabetes-related costs ($3,092, P < 0.05) in the 12-month post-index period, with most of the cost differences from lower outpatient costs.

CONCLUSIONS

DPNP patients who initiated duloxetine therapy were less likely to have subsequent opioid use and had lower health-care costs than SOC patients.

Medication adherence and healthcare costs among patients with diabetic peripheral neuropathic pain initiating duloxetine versus pregabalin

OBJECTIVE

To examine the impact of medication choice between duloxetine or pregabalin on medication adherence and direct healthcare costs among patients with diabetic peripheral neuropathic pain (DPNP).

METHODS

A retrospective cohort study design was used with a large US national administrative claims database. Commercially-insured DPNP patients aged 18-64 years who initiated duloxetine or pregabalin in 2006 were selected, with the first initiation date as the index date. All selected patients had 12 months continuous enrollment in the pre- and post-index periods, and were grouped into the duloxetine or pregabalin cohort based on the index agent. The duloxetine and pregabalin cohorts were constructed via propensity score stratification with similar demographics, co-morbid medical conditions, pre-index healthcare utilization and costs, and prior treatment patterns. Medication possession ratio (MPR), proportion of patients with MPR ≥ 0.8 and healthcare costs over the 12-month post-index period were compared between cohorts.

RESULTS

Both the duloxetine (n = 794) and pregabalin (n = 1779) cohorts had a mean age of 56 years, and 58% of female. Common co-morbid conditions among duloxetine and pregabalin patients were cardiovascular disease (82.5 vs. 82.2%), neuropathic pain other than DPNP (71.1 vs. 72.7%), osteoarthritis (39.0 vs. 41.3%), and low back pain (29.4 vs. 30.5%). More than 73% of the patients had opioid use prior to the initiation of duloxetine or pregabalin. Among patients with similar demographic, clinical and economic characteristics, and prior treatment patterns, duloxetine-treated patients had significantly higher MPR (0.34 vs. 0.13), higher proportion of patients with MPR ≥ 0.8 (15.5 vs. 0.7%), and significantly lower total healthcare costs ($34,146 vs. 34,897) over the 12-month post-index period than pregabalin-treated patients (all p < 0.05).

CONCLUSIONS

Commercially-insured DPNP patients initiating duloxetine had significantly higher medication adherence and lower healthcare costs than those initiating pregabalin.

The relationship between average daily dose, medication adherence, and health-care costs among diabetic peripheral neuropathic pain patients initiated on duloxetine therapy

OBJECTIVE

To examine the relationship between average daily dose (ADD) of duloxetine, adherence to therapy, and health-care costs among patients with diabetic peripheral neuropathic pain (DPNP).

METHODS

A retrospective analysis of commercially insured DPNP patients was conducted among those aged 18 to 64 years who initiated duloxetine therapy between Ocotober 1, 2004 and December 31, 2006. The dispense date of the first duloxetine prescription was defined as the index date. All duloxetine prescriptions over the 12-month post-index period were used to assess ADD and adherence. Four study cohorts were constructed based on ADD: 30 mg, 31 to 59 mg, 60 mg; and >60 mg. High adherence was defined as having a medication possession ratio for duloxetine of ≥0.8. Health-care costs over 12-month post-index period were estimated. Multiple regression models were used to examine the association between ADD, adherence, and health-care costs.

RESULTS

The study sample included 1,351 DPNP patients (mean age: 55 years; male: 41%). Twelve percent of patients had a duloxetine ADD of 30 mg, 17% of 31 to 59 mg, 56% of 60 mg, and 15% of >60 mg. Patients with ADD of 30 mg (>60 mg) were significantly less (more) likely to adhere to duloxetine therapy compared with those in the 60 mg cohort. Controlling for cross-cohort demographic and clinical differences, patients with ADD of 30 mg, 31 to 59 mg, or >60 mg had significantly higher total health-care costs than those with ADD of 60 mg (adjusted differences: $6,090, $6,320, $6,466 for 30 mg, 31 to 59 mg, >60 mg, respectively, all P < 0.05).

CONCLUSION

The findings suggest that having an ADD of 60 mg for duloxetine among commercially insured DPNP patients is associated with improved medication adherence and lower health-care costs.

Clinical Approach to the Treatment of Painful Diabetic Neuropathy

Painful neuropathy is a common and often progressive complication of diabetes. Patients frequently report symptoms of tingling, burning, lancinating pain, hyperesthesia and allodynia. The natural history of the disease may vary from intermittent mild symptoms to severe chronic daily pain; the latter is often associated with diminished quality of life. There are a variety of pharmaceutical agents from different medicinal categories available for the symptomatic treatment of painful diabetic neuropathy, however selecting an agent is often challenging given the breadth of choices and lack of consistent guidelines. As a result, many patients remain untreated or undertreated.This article presents a practical clinical approach to the treatment of pain in diabetic neuropathy. Recommendations for first, second and third line medications are based on specific evidence for the treatment of painful diabetic neuropathy as well as safety, tolerability, drug interactions and cost. Additional topics of discussion include breakthrough pain, opioid use and topical therapies. This review does not comprehensively discuss all possible treatments for painful neuropathy, but provides a systematic approach designed to guide clinicians in tailoring therapies to the individual patient.

Altered nerve excitability in subclinical/early diabetic neuropathy: evidence for early neurovascular process in diabetes mellitus?

We sought to investigate the peripheral nerve excitability property of early diabetic neuropathy (DN) and provide a logical hypothesis regarding the pathophysiology of subclinical/early stage of DN. The automated nerve excitability test (NET) utilizing the threshold tracking technique (TTT) was performed to measure multiple excitability indices in 30 early DN and 30 normal subjects. Early DN was defined as N0 or N1 stage of Dyck's staging method. The protocols calculated strength-duration time constant (SDTC) from duration-charge curve, parameters of threshold electrotonus (TE) and current-threshold relationship (CTR) from sequential sub-threshold current, and recovery cycle (RC) from double supra-threshold stimulation. Each parameter of test was co-analyzed with clinical and laboratory data including age, sex, BMI, HgbA1c, lipid profile, and estimated glomerular filtration rate (eGFR). Compared to normal or N0 groups, N1 group had 'fanning-in' phenomenon in TE, increased refractory period, and decreased supernormality/subnormality. Linear regression showed that parameters associated with vascular factor were significantly related with STDC: absolute TG values were positively associated with STDC, whereas eGFR values were inversely related with STDC. Nerve excitability can be altered even in the early mild DN. The pattern of alteration suggests depolarizing nerve or nerve ischemia in pathophysiology of subclinical/early DN.

Opioid use and healthcare costs among patients with DPNP initiating duloxetine versus other treatments

OBJECTIVE

To compare opioid utilization and healthcare costs over a 1-year period following the initiation with duloxetine versus other standard of care (SOC) treatments among patients with diabetic peripheral neuropathic pain (DPNP).

METHODS

This retrospective cohort study assessed commercially-insured DPNP patients between 18 and 64 years old who initiated duloxetine or other SOC treatments (tricyclic antidepressants, venlafaxine, gabapentin, pregabalin) between 3/1/2005 and 12/31/2005. Initiation was defined as a 90-day period without available study medication. The first dispense date of the study medication was denoted as the index date. Selected patients had no opioid pill coverage during the 90 days prior to initiation. Duloxetine and SOC patients were matched via propensity scoring (1:1 ratio), controlling for demographics, comorbidities, prior healthcare utilization and costs, and prior medication history. Opioid utilization and healthcare costs over the 12-month post-index period were compared between study cohorts.

RESULTS

The matched sample included 117 patients in each of the duloxetine and SOC cohorts. Compared with SOC-treated patients, duloxetine-treated patients were less likely to use any opioids (52.1 vs. 84.6%, p < 0.05) over the 12-month post-index period. Duloxetine-treated patients, on average, had two fewer opioid prescriptions dispensed, 27 fewer days on opioids, 121 days greater delay in subsequent opioid use, and 1815 mg lower morphine equivalent dosage than SOC-treated patients (all p < 0.05). Also, duloxetine-treated patients had significantly lower total ($18,623 vs. 30,602, p < 0.05) and outpatient costs ($7371 vs. 15,343, p < 0.05). Due to the use of a retrospective administrative claims database, limitations of this study include the potential for selection bias between study cohorts, and inability to measure unobservable confounding and disease severity and/or duration.

CONCLUSIONS

Among commercially-insured DPNP patients, duloxetine-treated patients had delayed and reduced opioid use and lower healthcare costs than SOC-treated patients.

Safety and tolerability of duloxetine in the acute management of diabetic peripheral neuropathic pain: analysis of pooled data from three placebo-controlled clinical trials

OBJECTIVE

Summarize safety and tolerability of duloxetine in treating diabetic peripheral neuropathic pain.

RESEARCH DESIGN AND METHODS

Pooled data from three double-blind, randomized studies with 12-week, placebo-controlled (acute) and 52-week, routine-care-controlled (extension) phases.

MAIN OUTCOME MEASURES

Frequency/discontinuations due to treatment-emergent adverse events (TEAEs).

RESULTS

There were 1139 (placebo, n = 339; duloxetine, n = 800) and 867 (routine-care, n = 287; duloxetine, n = 580) patients in the acute and extension phases, respectively. Patient details were as follow: 60 years (mean age); Caucasian, 84%; and male, 57%. In the acute phase, there were significantly more TEAEs, duloxetine versus placebo (p = 0.001), the most common being nausea and somnolence. Discontinuations due to adverse events were significantly greater (12.5 vs 5.6%, p < 0.001), with similar outcomes in the extension phase. Baseline-to-endpoint aspartate transaminase/alanine transaminase were significantly increased and fasting plasma glucose was increased for duloxetine (0.67 mmol/l) versus decreased in routine-care (-0.64 mmol/l, p < 0.001). HbA1c was significantly increased, duloxetine vs routine-care, in the extension phase (52 vs 19%, p < 0.001). Endpoint measures neuropathy, nephropathy and retinopathy indicated no disease progression.

CONCLUSIONS

Duloxetine was generally safe and well tolerated, with the three most commonly reported TEAEs being nausea, somnolence and constipation. Modest changes in glycemia were associated with duloxetine. Aspartate transaminase/alanine transaminase increases were transient and not considered predictive of more severe outcomes.

Changes in opioid use and healthcare costs among U.S. patients with diabetic peripheral neuropathic pain treated with duloxetine compared with other therapies

OBJECTIVE

To examine changes in opioid use and healthcare costs among commercially insured patients with diabetic peripheral neuropathic pain (DPNP) who initiated duloxetine versus other standard of care (SOC) medications (tricyclic antidepressants, venlafaxine, gabapentin, pregabalin).

RESEARCH DESIGN AND METHODS

Using an administrative claims database, patients with DPNP aged 18-64 who initiated duloxetine or SOC between March 1, 2005 and December 31, 2005 were identified. Initiation was defined as a 90-day clean period without the available study medication. Selected patients had 12 months of continuous enrollment before and after the index date, and at least one opioid dispensed in the prior 90 days. Duloxetine and SOC patients were further classified into continuous and non-continuous users based on whether the medication possession ratio was > or =0.8. Total opioid days, number of opioid prescriptions dispensed, and cumulative morphine equivalents were examined over the 12-month pre- and post-index periods. Multivariate regressions were applied to assess the changes (pre-index minus post-index) in opioid use (total, short-acting vs. long-acting) and healthcare costs, controlling for demographic and clinical characteristics.

RESULTS

The study sample included 1281 patients: 98 duloxetine continuous, 243 duloxetine non-continuous, 195 SOC continuous, and 745 SOC non-continuous users. Controlling for demographic and clinical characteristics, duloxetine non-continuous and SOC (continuous and non-continuous) patients had significantly less reduction in total opioid days (-24.4, -23.7, -18.5, respectively, all p < 0.05) from the 12-month pre-index to the post-index period than duloxetine continuous patients. Compared with duloxetine non-continuous, SOC continuous, and SOC non-continuous users, duloxetine continuous users had a greater reduction in short-acting hydrocodone use (difference between the 12 month pre-index and post-index periods) in terms of the total number of prescriptions dispensed (adjusted differences: 1.5, 1.7, 1.7, respectively, all p < 0.05), total supply days (adjusted differences: 28.1, 27.3, 29.7, respectively, all p < 0.05), and morphine equivalent dosage (adjusted differences: 1290 mg, 1132 mg, 1127 mg, respectively, all p < 0.05). Duloxetine non-continuous patients had significantly higher adjusted total ($12,729, p < 0.05) and inpatient costs ($14,993, p < 0.05) than duloxetine continuous patients.

LIMITATIONS

Due to the use of a retrospective administrative claims database, this study is subject to selection bias between study cohorts, misidentification of DPNP and/or other comorbidities, and an inability to confirm adherence to therapy or assess indirect costs and costs of over-the-counter medications.

CONCLUSIONS

Among commercially insured patients with DPNP, continuous treatment with duloxetine was associated with a reduction in opioid use between the 12-month pre- and post-index periods compared with treatment with SOC or non-continuous treatment with duloxetine. Duloxetine continuous patients also incurred lower subsequent healthcare costs than non-continuous duloxetine patients.

Effect of dipeptidyl peptidase-IV (DPP-IV) inhibitor (Vildagliptin) on peripheral nerves in streptozotocin-induced diabetic rats

BACKGROUND AND AIMS

The aim of this study was to investigate the GLP-1 pathway effect on peripheral nerves using a DPP-IV inhibitor in streptozotocin (STZ)-induced diabetic rats.

METHODS

Adult male Sprague Dawley rats were divided into four groups and two groups (n=6 in each) were given a DPP-IV inhibitor of 0.3mg/kg/day or 10mg/kg/day dissolved in water. Intraepidermal innervation was quantified as nerve fiber abundance per unit length of epidermis (IENF/mm) following an immunohistochemical procedure using the polyclonal antibody of anti-protein gene product 9.5 (PGP 9.5).

RESULTS

Daily administration of DPP-IV inhibitor to the experimental diabetes model at doses of 10mg/kg for 32 weeks protected nerve fiber loss compared with untreated rats as follows (IENF/mm): normal (9.89+/-0.34), diabetes mellitus (DM) (8.42+/-0.28), DM with 0.3mg/kg DPP-IV inhibitor (9.88+/-0.38), and DM with 10mg/kg DPP-IV inhibitor (10.36+/-0.32) (p<0.05). There was a significant reduction (% change) in the decrease of intraepidermal nerve fiber density (IENFD) in the DPP-IV inhibitor-treated groups during the experimental period: normal (10.1%), DM (25.8%), DM with 0.3mg/kg DPP-IV inhibitor (13.3%), and DM with 10mg/kg DPP-IV inhibitor (7.9%) (p<0.05).

CONCLUSIONS

Our study suggests that a DPP-IV inhibitor may prevent peripheral nerve degeneration in a diabetes-induced animal model and support the idea that GLP-1 may be useful in peripheral neuropathy.

How do changes in pain severity levels correspond to changes in health status and function in patients with painful diabetic peripheral neuropathy?

The current analysis compares changes in pain with changes in function and health status in individuals with painful diabetic peripheral neuropathy (DPN). The post hoc analysis is based on a 12week, multinational, placebo-controlled trial of pregabalin in which 401 patients were randomized to treatment. Study measures included the Brief Pain Inventory short-form (BPI-sf), EQ-5D and other patient-reported outcomes. Cutpoints were derived on the BPI-sf 0-10 average pain numeric rating scale [NRS] to classify pain grades of "mild" (1-3), moderate (4-6) and severe (7-10), adjusting for geographical regions where data were collected. Two different metrics were used to classify the importance of change in pain severity from baseline to 12weeks: changes in pain severity grades (defined by cutpoint categories) and percent reduction in the NRS (categories ranging from 0-9% to 50%). An improvement in one pain grade or a 30% reduction in the NRS served as determinants of a clinically important difference. Patients with a one-grade reduction in pain severity, either from "severe-to-moderate" or "moderate-to-mild," had a 3-point improvement the BPI-sf Pain Interference Index (PII; a composite measure of function); a reduction from "severe-to-mild" pain corresponded to a 6-point improvement in the PII. Similarly, a reduction in the NRS of 30% and 50% corresponded to a 3-point and a 5-point improvement in the PII, respectively. Changes in pain were also associated with changes in health status. Results suggest that patients whose pain is not reduced to a mild level of severity can still experience clinically important changes in function and health status.

Evaluation of healthcare resource utilization and costs in employees with pain associated with diabetic peripheral neuropathy treated with pregabalin or duloxetine

OBJECTIVE

To evaluate changes in healthcare resource use and costs after initiating pregabalin or duloxetine in employees with pain associated with diabetic peripheral neuropathy (pDPN).

METHODS

Employees (18-64 years old) with a DPN diagnosis and at least one pDPN-related pain medication claim were identified using the MarketScan Commercial Database (2005-2008). Propensity scored matched pregabalin and duloxetine new starts were evaluated in the 6-month pre- and 6-month post-initiation periods. Study outcomes including imputed medically-related work loss, prescription and healthcare utilization, and associated expenditures were analyzed using univariate statistics and multivariate models in a difference-in-difference approach.

RESULTS

A total of 473 employees in each treatment group were identified. Mean age was 53.6 (SD 7.0) years for pregabalin and 53.5 (SD 7.4) years for duloxetine. There were no pre-index differences between groups. Adjusted marginal effects were not statistically significant for pre-to-post changes in opioid utilization (p = 0.328), number of pDPN-related analgesic medications (p = 0.506), all-cause healthcare costs (p = 0.895), indirect costs (p = 0.324), or pDPN-attributable expenditures (p = 0.359).

LIMITATIONS

Claims analysis is limited in accounting for all patient and plan differences, and by the reliability of medical claims for diagnosis coding. The sample size of the matched cohorts may have limited the power of the analysis to detect differences.

CONCLUSIONS

There were no significant pre-to-post differences between pregabalin and duloxetine treatment groups in pDPN-related analgesic medication use, or pDPN-attributable, all-cause, and indirect expenditures.

Prevalence of other diabetes-associated complications and comorbidities and its impact on health care charges among patients with diabetic neuropathy

INTRODUCTION

Diabetic neuropathy (DN) is a common complication associated with diabetes. This study assesses the prevalence of other diabetes-related complications or comorbidities among DN patients and its marginal contribution to health care charges.

METHODS

Using administrative claims database, we studied commercially insured patients below 65 years old with at least one claim of DN anytime from July 2004 through June 2005 (Year 1). Using propensity scoring, a 10:1 ratio of demographically matched controls with diabetes but no DN was constructed. Both DN patients and controls had 12 months of continuous enrollment in Year 1 and Year 2 (July 2005-June 2006). We compared the Year 1 prevalence of other diabetes-associated complications or comorbidities between DN patients and diabetic controls. Controlling for comorbidities, we used multivariate regressions to examine the incremental impact of DN or any other diabetes-related complication or comorbidity on Year 2 health care charges.

RESULTS

A higher percentage of DN patients had at least one other diabetes-related complication or comorbidity than diabetic controls. Individuals with DN had a higher prevalence of each individual other diabetes-related complication or comorbidity. Controlling for comorbidities, the presence of any other diabetes-related complication or comorbidity was statistically associated with higher outpatient pharmacy and total charges for both DN patients and controls. Total and outpatient pharmacy charges were also significantly higher for DN patients than for controls, among those with or without any other diabetes-related complications or comorbidities.

CONCLUSIONS

DN can occur in the absence of other diabetes-related complications or comorbidities. The presence of DN and any other diabetes-related complications or comorbidities significantly increases health care charges.

Low-frequency BOLD fluctuations demonstrate altered thalamocortical connectivity in diabetic neuropathic pain

Background

In this paper we explored thalamocortical functional connectivity in a group of eight patients suffering from peripheral neuropathic pain (diabetic pain), and compared it with that of a group of healthy subjects. We hypothesized that functional interconnections between the thalamus and cortex can be altered after years of ongoing chronic neuropathic pain.

Results

Functional connectivity was studied through a resting state functional magnetic resonance imaging (fMRI) paradigm: temporal correlations between predefined regions of interest (primary somatosensory cortex, ventral posterior lateral thalamic nucleus, medial dorsal thalamic nucleus) and the rest of the brain were systematically investigated. The patient group showed decreased resting state functional connectivity between the thalamus and the cortex.

Conclusion

This supports the idea that chronic pain can alter thalamocortical connections causing a disruption of thalamic feedback, and the view of chronic pain as a thalamocortical dysrhythmia.

Use of Antidepressants in the Treatment of Chronic Pain

Fibromyalgia syndrome (FMS) is a chronic and debilitating musculoskeletal pain disorder of unknown aetiology with usual accompanying features of fatigue, sleep disturbances and stiff- ness. Its place in medical textbooks was controversial with rheumatologists holding the helm of its management for many years. Over the last decade, abnormalities have been identified at multiple levels in the peripheral, central, and sympathetic nervous systems as well as the hypothalomo-pitutary-adrenal axis stress response system. With the elucidation of these pathways of pain, FMS is known more as a central sensitivity syndrome. This led to tremendous increment in interest in both pharmacological and non-pharmacological treatment of FMS. The United States Food and Drug Administration (FDA) has also successively approved 3 drugs for the management of fibromyalgia – pregabalin, duloxetine and milnacipran. Non-pharmacological modalities showed aerobic exercise, patient education and cognitive behavioural therapy to be most effective. Overall, management of FMS requires a multi-disciplinary approach. Key words: Aetiology, Fibromyalgia-Fibromyositis Syndromes, History, Pain syndrome

A survey of treatment practices in diabetic peripheral neuropathy

OBJECTIVE

To evaluate provider practices for identification and treatment of painful diabetic peripheral neuropathy (DPN).

METHODS

A questionnaire was distributed to healthcare providers attending educational programs in New England.

RESULTS

The survey was completed by 357 providers. Although generally ineffective in neuropathic pain, non-steroidal anti-inflammatory drugs were prescribed by 31% of providers. Only 57% providers used a quantitative pain scale to evaluate pain. The effectiveness of medications was assessed at least frequently by 70% of providers and at every visit by 22% providers.

CONCLUSION

The results reiterate the need for routinely monitoring patients with painful DPN and using appropriate pain scales.

Duloxetine compliance and its association with healthcare costs among patients with diabetic peripheral neuropathic pain

OBJECTIVE

Duloxetine is approved to treat diabetic peripheral neuropathic pain (DPNP) in the US. The study objective was to examine the predictors of duloxetine compliance, and its association with healthcare costs among DPNP patients.

METHODS

The study used administrative claims databases to identify non-depressed DPNP patients with a duloxetine prescription dispensed between October 1, 2004 and December 31, 2006. Two cohorts of patients were constructed based on compliance to duloxetine therapy over 1-year follow-up with high compliance defined as a medication possession ratio (MPR) > or =0.80. All-cause, diabetes-, and DPNP-related healthcare costs during 1-year follow-up were estimated. Logistic regressions were performed to examine how average daily dose (ADD) of duloxetine and other factors may influence compliance. Multivariate regressions were estimated to examine the association between compliance and healthcare costs.

RESULTS

The study included 1,380 commercially insured (mean age 55 years) and 974 patients with employer-sponsored Medicare supplemental insurance (mean age 75 years). In both populations, patients with an ADD >30 mg were more likely to be compliant with the therapy compared with those with an ADD of < or =30 mg (odds ratio ranged 1.79-3.38, all p<0.05). Controlling for differences in demographics, clinical and economic characteristics, commercially insured low duloxetine compliance patients had greater all-cause ($5,334, p<0.05) and diabetes-related healthcare costs ($3,414, p<0.05) than high-compliance patients, with the biggest difference from inpatient costs (all-cause: $7,508; diabetes-related: $3,785, all p<0.05). Similar trends were found in the Medicare supplemental insured population; however, differences in all-cause healthcare costs were not significant.

CONCLUSIONS

DPNP patients with a higher ADD of duloxetine over a 1-year follow-up period were more compliant with the therapy. Duloxetine patients with high compliance were also associated with lower healthcare costs. Due to the use of a retrospective cohort design on administrative claims database, limitations of this analysis include a lack of formal diagnostic testing of patients, and inability to infer causality or measure factors such as DPNP severity that are not captured in such database.

Prevalence and impact on quality of life of peripheral neuropathy with or without neuropathic pain in type 1 and type 2 diabetic patients attending hospital outpatients clinics

AIMS

Diabetic polyneuropathy (DPN) without or with neuropathic pain (DPN-P) is one of the most frequent complications of diabetes. To better delineate their respective prevalences, we conducted a cross-sectional study that included 1111 patients (767 type 2 and 344 type 1 diabetic patients) followed up in diabetic outpatients clinics. The association of DPN and DPN-P with other diabetic complications, the impact on quality of life (QoL) and pain management were also investigated.

METHODS

Two validated tools (Neuropen) and the DN4 questionnaire) were used to diagnose the two conditions. Pain intensity was measured using a visual analogue scale, and participants completed the 12-item Short-Form Health Survey to evaluate the physical and mental components of QoL. Univariate and multivariate models were used for the statistical analyses.

RESULTS

The prevalence of DPN was 43% (95% CI 40.1-45.9), and was higher in type 2 (50.8%) than in type 1 (25.6%) diabetic patients. The prevalence of DPN-P was 14% (95% CI 12.1-16.2) which, again, was higher in type 2 (17.9%) than in type 1 (5.8%) patients. These prevalences both increased with age and diabetes duration. Nephropathy, obesity, low HDL cholesterol and high triglyceride levels were independently associated with DPN and/or DPN-P. Physical and mental components of QoL were significantly altered by DPN-P, but not DPN. Only half of the DPN-P patients were using analgesic treatment, while 28% were using anticonvulsants or antidepressants.

CONCLUSION

DPN and DPN-P are frequent complications of diabetes, especially in type 2, and can be identified with inexpensive and easy-to-use screening tools. Despite its profound impact on QoL, DPN-P remains undertreated.

The prevalence of neuropathic pain: clinical evaluation compared with screening tools in a community population

BACKGROUND

Neuropathic pain is reported to be common based on studies from specialty centers and survey studies. However, few prevalence estimates have been completed in a community population using clinical evaluation.

OBJECTIVE

To develop an estimate of the prevalence of neuropathic pain in community-dwelling adults.

METHODS

Data from a mailed survey (N = 3,575 community respondents), telephone interview (N = 907), and a clinical examination (N = 205) were linked to estimate the population prevalence of neuropathic pain. Using the clinical examination as the "gold" standard, estimates from several screening tools were developed and adjusted to the Olmsted County, MN adult population.

RESULTS

The estimated community prevalence of neuropathic pain from the clinical examination (gold standard) was 9.8%. Most other estimates were lower, including a 3.0% population prevalence using the Berger criteria and 8.8% using the Leeds Assessment of Neuropathic Symptoms and Signs. Only the prevalence rate based on self-report of nerve pain was higher (12.4%). Overlap among the groups each tool identified as having "neuropathic predominant pain" was only modest and the groups had significantly different rates of depressive symptoms, anxiety, limited functional ability, and use of complementary and alternative medicine.

CONCLUSIONS

The estimated rates and personal characteristics of community residents with "neuropathic pain" vary widely depending on the tools used to identify neuropathic pain. None of the screening tools compared well with clinical evaluation. The differences in the groups identified by alternative screening methods become of major importance when reporting neuropathic pain epidemiology, studying therapies for neuropathic pain, or attempting to translate neuropathic pain research into clinical practice.

Comparing clinical and economic characteristics between commercially-insured patients with diabetic neuropathy and demographically-matched diabetic controls

OBJECTIVE

To examine medical conditions associated with diabetic neuropathy (DN) and to identify drivers of healthcare charges and utilization using administrative claims.

METHODS

The study examined commercially-insured under-age-65 individuals with 24 months continuous enrollment in a large US national health plan. DN patients were identified by having at least one claim with a DN diagnosis between July 2004 and June 2005. A demographically-matched control cohort of patients with diabetes but no DN (10: 1 ratio) was constructed using propensity scoring. Overall illness burden via a comprehensive disease classification, year 2 (July 2005 through June 2006) distribution of charges, and reasons for inpatient admissions and emergency room (ER) visits were compared between DN patients and diabetic controls. Multivariate regressions were used to assess the marginal contribution of DN to healthcare charges and utilization, and the most common reasons for ER and inpatient admissions, controlling for differences in overall illness burden.

RESULTS

Both DN patients (n = 8655) and diabetic controls (n = 86 550) had a mean age of 51 years, and 46% were female. Compared with controls, DN patients had more comorbid medical conditions (9.7 vs. 6.8, p < 0.05) and higher total healthcare charges. Controlling for differences in overall illness burden, DN patients had significantly more hospital days (0.67), more ER (0.09), physician office (0.62), and outpatient hospital visits (2.87), and higher total healthcare charges ($5696) than controls (all p < 0.05), with majority of the difference in charges from inpatient service ($3975, p < 0.05). Patients with DN were also far more likely to be hospitalized (ketoacidosis, neurological manifestation, heart disease, skin infection) or have an ER encounter (amputation) for diabetes-related complications. Due to the use of a retrospective claims database, limitations of this analysis include a lack of formal diagnostic testing of patients, inability to measure factors such as disease duration and severity that are not captured in such databases, and the possible lack of generalization from this group of patients with diabetes to other populations.

CONCLUSIONS

DN patients had significantly more comorbid medical conditions and higher healthcare charges and utilization than age- and sex-matched diabetic controls. Controlling for differences in overall illness burden, DN patients incurred more ER visits and inpatient admissions.

Effects of grape seed proanthocyanidin extracts on peripheral nerves in streptozocin-induced diabetic rats

Diabetic peripheral neuropathy (DPN) is one of the most common diabetic chronic complications. The aim of this study was to clarify whether grape seed proanthocyanidins extracts (GSPE) are therapeutic agents against DPN. In this study, we used streptozocin (STZ) to induce diabetic rats. GSPEs (250 mg/kg body weight/d) were administrated to diabetic rats for 24 wk. Motor nerve conductive velocity (MNCV) and mechanical hyperalgesia were determined in the rats. Serum glucose, glycated hemoglobin, advanced glycation end products (AGEs), and tissue malondialdehyde (MDA) and superoxide dismutase (SOD) were determined. Light and electron microscopy were used to observe the changes of nerval ultrastructure.GSPE significantly increased the MNCV, mechanical hyperalgesia and SOD of diabetic rats (p<0.05) and reduced the AGEs and MDA of diabetic rats (p<0.05). After being treated by GSPE, the severe segmental demyelination was decreased and Schwann cells were improved. In conclusion, GSPE plays an important role against DPN. With the decreasing of AGEs and MDA, it can ameliorate oxidation-associated nerval damage. This study may provide a new recognition of natural medicine for the treatment of DPN.