Validation of a modified version of the brief pain inventory for painful diabetic peripheral neuropathy

Efficacy and Safety of Trazodone and Gabapentin Fixed-Dose Combination in Patients Affected by Painful Diabetic Neuropathy: Randomized, Controlled, Dose-Finding Study

INTRODUCTION

Up to 50% of diabetic patients with neuropathy suffer from chronic pain, namely painful diabetic neuropathy (PDN), an unmet medical need with significant impact on quality of life. Gabapentin is widely used for PDN, albeit with frequent dose-limiting effects. Trazodone, an antidepressant with multi-modal action, has shown promising results when given at low doses as an add-on to gabapentin. Upon previous clinical trials and experimental evidence, a fixed-dose combination (FDC) of both compounds, at low doses, was developed for neuropathic pain.

METHODS

This was a phase II, randomized, double-blind, placebo and reference controlled, dose-finding, multicenter, international, prospective study. Male and female diabetic patients aged 18-75 years and affected by PDN were eligible for enrolment. Patients were randomized (1:1:1:1:2 ratio) to trazodone and gabapentin (Trazo/Gaba) 2.5/25 mg t.i.d. for 8 weeks, Trazo/Gaba 5/50 mg t.i.d. for 8 weeks, Trazo/Gaba 10/100 mg t.i.d. for 8 weeks, gabapentin (Gaba), or placebo (PLB). The aim of the study was to collect preliminary information on the effect of the 3 different FDCs of Trazo/Gaba on pain intensity based on the 11-point numeric rating score (NRS) after 8 weeks of treatment. The secondary objectives were the evaluation of the percentage of responders, neuropathic pain symptoms, anxiety, sleep, quality of life, safety, and tolerability. The primary efficacy endpoint was evaluated with last observation carried out forward (LOCF), using an analysis of covariance (ANCOVA), including treatment and centers as factors and baseline as covariate and applying linear contrast test, excluding the active treatment. Only if the linear contrast test was significant (p < 0.05), the step-down Dunnett test would be used to determine the minimum effective dose significantly different from PLB. If linearity was not verified, an adjusted ANCOVA model and comparisons with Dunnett test were performed. Before the application of the ANCOVA model, the non-significance of interaction treatment per baseline was verified.

RESULTS

A total of 240 patients were included in the modified intention-to-treat (m-ITT) population: 39 in Trazo/Gaba 2.5/25 mg, 38 in Trazo/Gaba 5/50 mg, 37 in Trazo/Gaba 10/100 mg, 83 in PLB, and 43 in Gaba. After 8 weeks of treatment, changes of the average daily pain score based on the 11-point NRS from baseline were - 2.52 ± 2.31 in Trazo/Gaba 2.5/25 mg group, - 2.24 ± 1.96 in Trazo/Gaba 5/50 mg group, - 2.46 ± 2.12 in Trazo/Gaba 10/100 mg group, - 1.92 ± 2.21 in Gaba group, and - 2.02 ± 1.95 in the PLB group. The linear contrast test did not result in significant differences (p > 0.05) among treatment groups. Consequently, the minimum effective dose against PLB was not determined. The multiple comparison with Dunnett adjustment did not show any statistically significant differences vs. PLB after 8 weeks of treatment: Trazo/Gaba 2.5/25 mg (95% confidence interval (CI) - 1.2739, 0.2026; p = 0.1539); Trazo/Gaba 5/50 mg (95% CI - 0.9401, 0.5390; p = 0.5931); Trazo/Gaba 10/100 mg (95% CI - 1.0342, 0.4582; p = 0.4471). However, patients receiving the lowest dose of Trazo/Gaba 2.5/25 mg showed a statistically significant difference to PLB after 6 weeks of treatment (95% CI - 1.6648, - 0.2126; p = 0.0116). Positive results were also found for responder patients, other items related to the pain, anxiety, depression, sleep, and quality of life, consistently in favor to the lowest Trazo/Gaba FDC. Two serious adverse events (SAEs) occurred but were judged unrelated to the study treatment. Treatment-emergent adverse events (TEAEs) were mainly mild-to-moderate in intensity and involved primarily nervous system, gastrointestinal disorders, and investigations.

CONCLUSIONS

The primary end point of the study was the change from baseline of the average daily pain score based on the 11-point NRS after 8 weeks of treatment. While the primary endpoint was not reached, patients treated with Trazo/Gaba 2.5/25 mg t.i.d. showed statistically significant improvement of pain and other scores after 6 weeks and reported consistent better results in comparison to PLB on primary and secondary endpoints for the overall study duration. According to these results, the lowest dose of Trazo/Gaba FDC may be the best candidate for further clinical development to confirm the potential benefits of the FDC drug for this condition.

CLINICAL TRIAL REGISTRATION

NCT03749642.

Efficacy and Safety of LX9211 for Relief of Diabetic Peripheral Neuropathic Pain (RELIEF-DPN 1): Results of a Double-Blind, Randomized, Placebo-Controlled, Proof-of-Concept Study

OBJECTIVE

To evaluate the efficacy of LX9211 in reducing pain related to diabetic peripheral neuropathy.

RESEARCH DESIGN AND METHODS

In this double-blind, multicenter, proof-of-concept trial, 319 individuals with diabetic peripheral neuropathic pain (DPNP) were randomized (1:1:1) to LX9211 10 mg (n = 106), LX9211 20 mg (n = 106), or matching placebo (n = 107), administered once daily for 6 weeks. DPNP was rated daily with an 11-point numerical rating scale. The primary end point was change from baseline to week 6 in the average daily pain score. The difference between each LX9211 group and placebo was evaluated with mixed-model repeated-measures analysis.

RESULTS

For those on low-dose LX9211 the primary efficacy end point was achieved: -1.39 vs. -0.72 points for placebo, least squares mean (SE) difference -0.67 (0.249), 95% CI -1.16 to -0.18, P = 0.007; results for high-dose LX9211 demonstrated improvement in pain severity versus placebo (-1.27 vs. -0.72 points, respectively), but the between-group LS mean difference did not reach the prespecified statistical significance (-0.55 [0.254], 95% CI -1.06 to -0.05, P = 0.030). Treatment benefit was observed beginning at week 1 and maintained thereafter. Results for LX9211 also demonstrated improvement in several patient-reported secondary outcomes. Most common adverse events (AEs) were dizziness, nausea, and headache. More participants treated with LX9211 (20 mg, n = 28 [26.4%]; 10 mg, 17 [16.0%]) than placebo (3 [2.8%]) discontinued study drug prematurely due to AEs; serious AEs were uncommon (2 [1.9%], 0, and 1 [0.9%], respectively).

CONCLUSIONS

These preliminary findings of improvement in DPNP with LX9211 support further investigation in larger trials.

Pathology of pain and its implications for therapeutic interventions

Pain is estimated to affect more than 20% of the global population, imposing incalculable health and economic burdens. Effective pain management is crucial for individuals suffering from pain. However, the current methods for pain assessment and treatment fall short of clinical needs. Benefiting from advances in neuroscience and biotechnology, the neuronal circuits and molecular mechanisms critically involved in pain modulation have been elucidated. These research achievements have incited progress in identifying new diagnostic and therapeutic targets. In this review, we first introduce fundamental knowledge about pain, setting the stage for the subsequent contents. The review next delves into the molecular mechanisms underlying pain disorders, including gene mutation, epigenetic modification, posttranslational modification, inflammasome, signaling pathways and microbiota. To better present a comprehensive view of pain research, two prominent issues, sexual dimorphism and pain comorbidities, are discussed in detail based on current findings. The status quo of pain evaluation and manipulation is summarized. A series of improved and innovative pain management strategies, such as gene therapy, monoclonal antibody, brain-computer interface and microbial intervention, are making strides towards clinical application. We highlight existing limitations and future directions for enhancing the quality of preclinical and clinical research. Efforts to decipher the complexities of pain pathology will be instrumental in translating scientific discoveries into clinical practice, thereby improving pain management from bench to bedside.

Safety and Efficacy of Topiramate in Individuals With Cryptogenic Sensory Peripheral Neuropathy With Metabolic Syndrome: The TopCSPN Randomized Clinical Trial

Importance

Cryptogenic sensory peripheral neuropathy (CSPN) is highly prevalent and often disabling due to neuropathic pain. Metabolic syndrome and its components increase neuropathy risk. Diet and exercise have shown promise but are limited by poor adherence.

Objective

To determine whether topiramate can slow decline in intraepidermal nerve fiber density (IENFD) and/or neuropathy-specific quality of life measured using the Norfolk Quality of Life-Diabetic Neuropathy (NQOL-DN) scale.

Design, Setting, and Participants

Topiramate as a Disease-Modifying Therapy for CSPN (TopCSPN) was a double-blind, placebo-controlled, randomized clinical trial conducted between February 2018 and October 2021. TopCSPN was performed at 20 sites in the National Institutes of Health-funded Network for Excellence in Neurosciences Clinical Trials (NeuroNEXT). Individuals with CSPN and metabolic syndrome aged 18 to 80 years were screened and randomly assigned by body mass index (<30 vs ≥30), which is calculated as weight in kilograms divided by height in meters squared. Patients were excluded if they had poorly controlled diabetes, prior topiramate treatment, recurrent nephrolithiasis, type 1 diabetes, use of insulin within 3 months before screening, history of foot ulceration, planned bariatric surgery, history of alcohol or drug overuse in the 2 years before screening, family history of a hereditary neuropathy, or an alternative neuropathy cause.

Interventions

Participants received topiramate or matched placebo titrated to a maximum-tolerated dose of 100 mg per day.

Main Outcomes and Measures

IENFD and NQOL-DN score were co-primary outcome measures. A positive study was defined as efficacy in both or efficacy in one and noninferiority in the other.

Results

A total of 211 individuals were screened, and 132 were randomly assigned to treatment groups: 66 in the topiramate group and 66 in the placebo group. Age and sex were similar between groups (topiramate: mean [SD] age, 61 (10) years; 38 male [58%]; placebo: mean [SD] age, 62 (11) years; 44 male [67%]). The difference in change in IENFD and NQOL-DN score was noninferior but not superior in the intention-to-treat (ITT) analysis (IENFD, 0.21 fibers/mm per year; 95% CI, -0.43 to ∞ fibers/mm per year and NQOL-DN score, -1.52 points per year; 95% CI, -∞ to 1.19 points per year). A per-protocol analysis excluding noncompliant participants based on serum topiramate levels and those with major protocol deviations demonstrated superiority in NQOL-DN score (-3.69 points per year; 95% CI, -∞ to -0.73 points per year). Patients treated with topiramate had a mean (SD) annual change in IENFD of 0.56 fibers/mm per year relative to placebo (95% CI, -0.21 to ∞ fibers/mm per year). Although IENFD was stable in the topiramate group compared with a decline consistent with expected natural history, this difference did not demonstrate superiority.

Conclusion and Relevance

Topiramate did not slow IENFD decline or affect NQOL-DN score in the primary ITT analysis. Some participants were intolerant of topiramate. NQOL-DN score was superior among those compliant based on serum levels and without major protocol deviations.

Trial Registration

ClinicalTrials.gov Identifier: NCT02878798.

Painful Diabetic Peripheral Neuropathy: Practical Guidance and Challenges for Clinical Management

Painful diabetic peripheral neuropathy (PDPN) is present in nearly a quarter of people with diabetes. It is estimated to affect over 100 million people worldwide. PDPN is associated with impaired daily functioning, depression, sleep disturbance, financial instability, and a decreased quality of life. Despite its high prevalence and significant health burden, it remains an underdiagnosed and undertreated condition. PDPN is a complex pain phenomenon with the experience of pain associated with and exacerbated by poor sleep and low mood. A holistic approach to patient-centred care alongside the pharmacological therapy is required to maximise benefit. A key treatment challenge is managing patient expectation, as a good outcome from treatment is defined as a reduction in pain of 30-50%, with a complete pain-free outcome being rare. The future for the treatment of PDPN holds promise, despite a 20-year void in the licensing of new analgesic agents for neuropathic pain. There are over 50 new molecular entities reaching clinical development and several demonstrating benefit in early-stage clinical trials. We review the current approaches to its diagnosis, the tools, and questionnaires available to clinicians, international guidance on PDPN management, and existing pharmacological and non-pharmacological treatment options. We synthesise evidence and the guidance from the American Association of Clinical Endocrinology, American Academy of Neurology, American Diabetes Association, Diabetes Canada, German Diabetes Association, and the International Diabetes Federation into a practical guide to the treatment of PDPN and highlight the need for future research into mechanistic-based treatments in order to prioritise the development of personalised medicine.

A randomized controlled trial assessing the safety and efficacy of palmitoylethanolamide for treating diabetic-related peripheral neuropathic pain

Background

Peripheral neuropathy is a common complication of diabetes. The management of the associated neuropathic pain remains difficult to treat.

Objective

This study explored the safety, tolerability and efficacy of a palmitoylethanolamide (PEA) formulation in treating diabetic-related peripheral neuropathic pain (PNP). Secondary outcomes included systemic inflammation, sleep and mood changes in patients diagnosed with type 1 and type 2 diabetes and PNP.

Design

This study was a single-centre, quadruple-blinded, placebo-controlled trial with 70 participants receiving 600 mg of PEA or placebo daily, for 8 weeks, with a 94% rate of study participation completion. Primary outcomes were neuropathic pain and specific pain types (the BPI-DPN and NPSI). The secondary outcomes were sleep quality (MOS sleep scale), mood (DASS-21), glucose metabolism and inflammation.

Results

There was a significant reduction (P ≤ 0.001) in BPI-DPN total pain and pain interference, NPSI total score and sub-scores, except for evoked pain (P = 0.09) in the PEA group compared with the placebo group. The MOS sleep problem index and sub-scores significantly improved (P ≤ 0.001). DASS-21 depression scores significantly reduced (P = 0.03), but not anxiety or stress scores. Interleukin-6 and elevated C-reactive protein levels significantly reduced in the PEA group (P = 0.05), with no differences in fibrinogen between groups (P = 0.78) at treatment completion. There were no changes in safety pathology parameters, and the treatment was well tolerated.

Conclusions

The study demonstrated that the PEA formulation reduced diabetic peripheral neuropathic pain and inflammation along with improving mood and sleep. Further studies on the mechanistic effectiveness of PEA as an adjunct medicine and as a monotherapy pain analgesic are warranted.

Clinical Trial Registration

Registry name: Australian New Zealand Clinical Trials Registry (ANZCTR), Registration number: ACTRN12620001302943, Registration link: https://anzctr.org.au/Trial/Registration/TrialReview.aspx?id=380826, Actual study start date: 20 November 2020.

Xiaoketongbi Formula vs pregabalin for painful diabetic neuropathy: A single-center, randomized, single-blind, double-dummy, and parallel controlled clinical trial

BACKGROUND

We assessed the efficacy and safety of the Xiaoketongbi Formula (XF) vs. pregabalin in patients with painful diabetic neuropathy (PDN).

METHODS

Patients with PDN (n = 68) were included in a single-center, randomized, single-blind, double-dummy, parallel controlled clinical trial. The primary outcome was the change in the Brief Pain Inventory for Diabetic Peripheral Neuropathy (BPI-DPN). Secondary outcomes evaluated included the reduction of BPI-DPN >50%, changes in the numeric rating scale-11 (NRS-11) score for pain, Daily Sleep Interference Diary (DSID), Patient Global Impression of Change (PGIC), nerve conduction velocity (NCV), and adverse events.

RESULTS

After 10 weeks of treatment, the BPI-DPN score reduced from 42.44 ± 17.56 to 26.47 ± 22.22 and from 52.03 ± 14.30 to 37.85 ± 17.23 in the XF and pregabalin group (Ps  < 0.001), respectively. The difference in the absolute change in BPI-DPN score between both groups was -1.79 (95% CI: -9.09, 5.50; p = 0.625). In the XF and pregabalin groups, 44.1% (15/34) and 20.6% (7/34) of patients reported a BPI-DPN reduction >50% (p = 0.038), respectively. There were no significant differences between groups in NRS-11 and DSID (Ps  > 0.05). A significantly greater number of patients in the XF group felt "significantly improved" or "improved" than in the pregabalin group (35.3% (12/34) vs. 11.8% (4/34), p = 0.045). The absolute change in motor nerve conduction velocity of the right median nerve was significantly different between both groups (XF group 0.7 ± 2.3 vs. pregabalin group -2.2 ± 4.1, p = 0.004). No serious adverse events were reported in either group.

CONCLUSIONS

XF is equivalent to pregabalin in reducing pain symptoms and improves the quality of life in patients with PDN. In addition, XF has the potential to improve nerve function by increasing NCV.

High-Frequency 10-kHz Spinal Cord Stimulation Improves Health-Related Quality of Life in Patients With Refractory Painful Diabetic Neuropathy: 12-Month Results From a Randomized Controlled Trial

Objective

To evaluate high-frequency (10-kHz) spinal cord stimulation (SCS) treatment in refractory painful diabetic neuropathy.

Patients and Methods

A prospective, multicenter randomized controlled trial was conducted between Aug 28, 2017 and March 16, 2021, comparing conventional medical management (CMM) with 10-kHz SCS+CMM. The participants had hemoglobin A1c level of less than or equal to 10% and pain greater than or equal to 5 of 10 cm on visual analog scale, with painful diabetic neuropathy symptoms 12 months or more refractory to gabapentinoids and at least 1 other analgesic class. Assessments included measures of pain, neurologic function, and health-related quality of life (HRQoL) over 12 months with optional crossover at 6 months.

Results

The participants were randomized 1:1 to CMM (n=103) or 10-kHz SCS+CMM (n=113). At 6 months, 77 of 95 (81%) CMM group participants opted for crossover, whereas none of the 10-kHz SCS group participants did so. At 12 months, the mean pain relief from baseline among participants implanted with 10-kHz SCS was 74.3% (95% CI, 70.1-78.5), and 121 of 142 (85%) participants were treatment responders (≥50% pain relief). Treatment with 10-kHz SCS improved HRQoL, including a mean improvement in the EuroQol 5-dimensional questionnaire index score of 0.136 (95% CI, 0.104-0.169). The participants also reported significantly less pain interference with sleep, mood, and daily activities. At 12 months, 131 of 142 (92%) participants were "satisfied" or "very satisfied" with the 10-kHz SCS treatment.

Conclusion

The 10-kHz SCS treatment resulted in substantial pain relief and improvement in overall HRQoL 2.5- to 4.5-fold higher than the minimal clinically important difference. The outcomes were durable over 12 months and support 10-kHz SCS treatment in patients with refractory painful diabetic neuropathy.

Trial registration

clincaltrials.gov Identifier: NCT03228420.

Mechanistic approach towards diabetic neuropathy screening techniques and future challenges: A review

Diabetic neuropathy, also called peripheral diabetic neuropathy (PDN), is among the most significant diabetes health consequences, alongside diabetic nephropathy, diabetic cardiomyopathy and diabetic retinopathy. Diabetic neuropathy is the existence of signs and indications of peripheral nerve damage in patients with diabetes after other causes have been governed out. Diabetic neuropathy is a painful and severe complication of diabetes that affects roughly 20% of people. The development of diabetic neuropathy is regulated by blood arteries that nourish the peripheral nerves and metabolic problems such as increased stimulation of polyol pathway, loss of myo-inositol and enhanced non-enzymatic glycation. It's divided into four types based on where neurons are most affected: autonomic, peripheral, proximal, and focal, with each kind presenting different symptoms like numbing, gastrointestinal disorders, and heart concerns. Pharmacotherapy for neuropathic pain is complex and for many patients, effective treatment is lacking; as a result, scientific proof recommendations are crucial. As a result, the current demand is to give the most vital medications or combinations of drugs that work directly on the nerves to help diabetic neuropathy patients feel less pain without causing any adverse effects. In diabetic neuropathy research, animal models are ubiquitous, with rats and mice being the most typically chosen for various reasons. This review covers the epidemiology, clinical features, pathology, clinical symptom, mechanism of diabetic neuropathy development, diagnosis, screening models of animals, diabetic neuropathy pharmacotherapy.

Chronic neuropathic pain is more than a perception: Systems and methods for an integral characterization

The management of chronic neuropathic pain remains a challenge, because pain is subjective, and measuring it objectively is usually out of question. However, neuropathic pain is also a signal provided by maladaptive neuronal activity. Thus, the integral management of chronic neuropathic pain should not only rely on the subjective perception of the patient, but also on objective data that measures the evolution of neuronal activity. We will discuss different objective and subjective methods for the characterization of neuropathic pain. Additionally, the gaps and proposals for an integral management of chronic neuropathic pain will also be discussed. The current management that relies mostly on subjective measures has not been sufficient, therefore, this has hindered advances in pain management and clinical trials. If an integral characterization is achieved, clinical management and stratification for clinical trials could be based on both questionnaires and neuronal activity. Appropriate characterization may lead to an increased effectiveness for new therapies, and a better quality of life for neuropathic pain sufferers.

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).

Keratinocyte Biomarkers Distinguish Painful Diabetic Peripheral Neuropathy Patients and Correlate With Topical Lidocaine Responsiveness

This study investigated quantifiable measures of cutaneous innervation and algesic keratinocyte biomarkers to determine correlations with clinical measures of patient pain perception, with the intent to better discriminate between diabetic patients with painful diabetic peripheral neuropathy (PDPN) compared to patients with low-pain diabetic peripheral neuropathy (lpDPN) or healthy control subjects. A secondary objective was to determine if topical treatment with a 5% lidocaine patch resulted in correlative changes among the quantifiable biomarkers and clinical measures of pain perception, indicative of potential PDPN pain relief. This open-label proof-of-principle clinical research study consisted of a pre-treatment skin biopsy, a 4-week topical 5% lidocaine patch treatment regimen for all patients and controls, and a post-treatment skin biopsy. Clinical measures of pain and functional interference were used to monitor patient symptoms and response for correlation with quantitative skin biopsy biomarkers of innervation (PGP9.5 and CGRP), and epidermal keratinocyte biomarkers (Nav1.6, Nav1.7, CGRP). Importantly, comparable significant losses of epidermal neural innervation (intraepidermal nerve fibers; IENF) and dermal innervation were observed among PDPN and lpDPN patients compared with control subjects, indicating that innervation loss alone may not be the driver of pain in diabetic neuropathy. In pre-treatment biopsies, keratinocyte Nav1.6, Nav1.7, and CGRP immunolabeling were all significantly increased among PDPN patients compared with control subjects. Importantly, no keratinocyte biomarkers were significantly increased among the lpDPN group compared with control. In post-treatment biopsies, the keratinocyte Nav1.6, Nav1.7, and CGRP immunolabeling intensities were no longer different between control, lpDPN, or PDPN cohorts, indicating that lidocaine treatment modified the PDPN-related keratinocyte increases. Analysis of the PDPN responder population demonstrated that increased pretreatment keratinocyte biomarker immunolabeling for Nav1.6, Nav1.7, and CGRP correlated with positive outcomes to topical lidocaine treatment. Epidermal keratinocytes modulate the signaling of IENF, and several analgesic and algesic signaling systems have been identified. These results further implicate epidermal signaling mechanisms as modulators of neuropathic pain conditions, highlight a novel potential mode of action for topical treatments, and demonstrate the utility of comprehensive skin biopsy evaluation to identify novel biomarkers in clinical pain studies.

Breast Milk Production in Women Who Use Nipple Shields for Persistent Nipple Pain

OBJECTIVE

To examine relationships between nipple pain scores and 24-hour milk production volumes, breastfeeding and pumping frequencies, and breastfeeding duration in women using nipple shields for persistent nipple pain.

DESIGN

Secondary outcome analysis of a prospective cohort study.

SETTING

Research laboratory and participants' homes.

PARTICIPANTS

Twenty-five breastfeeding women (6 ± 4 weeks after birth) who used nipple shields for persistent nipple pain.

METHODS

We conducted a randomized trial to investigate the primary outcome of milk transfer with and without nipple shields among participants with and without nipple pain. Here, we report secondary outcomes of associations between 24-hour milk production, breastfeeding and pumping frequencies, breastfeeding durations, and intake in participants using a nipple shield for nipple pain. Participants completed demographic, health and breastfeeding questionnaires and, at two monitored breastfeeding sessions, completed a pain visual analogue scale and Brief Pain Inventory-Short Form (BPI-SF; total and subscale scores for pain interference with General Activity, Mood, Sleep, and Breastfeeding). Milk production (milliliters per 24 hours), feed volumes, and percentage of available milk removed were calculated from data and milk samples obtained by participants over one 24-hour period and at study visits. Participants logged 24-hour data on a customized research website. We used descriptive statistics as well as simple and multiple linear regression for analyses.

RESULTS

Milk production and feeding duration were not associated with nipple pain scores (visual analogue scale: p = .80, BPI-SF: p = .44). An increase in BPI-SF Breastfeeding subscale score of 1 unit, indicating pain interference with breastfeeding, was associated with a 0.28 decrease in breastfeeding frequency (p = .02) and an 18.8-ml decrease in 24-hour breastfeeding intake (p = .04).

CONCLUSION

Persistent nipple pain was associated with reduced breastfeeding frequency; therefore, continuing professional support is required to ensure adequate milk removal and pain management.

A qualitative study of the experience and impact of neuropathic pain in people living with HIV

Painful distal symmetrical polyneuropathy is common in HIV and is associated with reduced quality of life. Research has not explored the experience of neuropathic pain in people with HIV from a person-centred perspective. Therefore, a qualitative interview study was conducted to more deeply understand the experience and impact of neuropathic pain in this population. Semistructured interviews were conducted with 26 people with HIV and peripheral neuropathic pain symptoms. Interviews explored the impact of pain and participants' pain management strategies. Interviews were transcribed verbatim and analysed using thematic analysis. Four themes and 11 subthemes were identified. Theme 1 reflects the complex characterisation of neuropathic pain, including the perceived unusual nature of this pain and diagnostic uncertainty. Theme 2 centred on the interconnected impacts of pain on mood and functioning and includes how pain disrupts relationships and threatens social inclusion. Theme 3 reflects the struggle for pain relief, including participants' attempts to "exhaust all options" and limited success in finding lasting relief. The final theme describes how pain management is complicated by living with HIV; this theme includes the influence of HIV stigma on pain communication and pain as an unwanted reminder of HIV. These data support the relevance of investigating and targeting psychosocial factors to manage neuropathic pain in HIV.

Prevalence of low protein intake in 80+-year-old community-dwelling adults and association with dietary patterns and modifiable risk factors: a cross-sectional study

Low protein intake may accelerate age-related loss of lean mass and physical function. We investigated the prevalence of low protein intake (<1·0 g/kg/day) and the associations between dietary patterns, modifiable risk factors and low protein intake in self-reliant community-dwelling adults ≥ 80 years. This cross-sectional study consisted of two home visits. Data collection consisted of physical measurements (e.g. physical function, physical activity) and self-report of nutritional intake (4-d food records), appetite, eating symptoms and medical conditions. Binary analyses were performed to compare participants with low and normal protein intake. Multiple logistic regression analyses were performed to investigate associations between low protein intake, dietary patterns and modifiable risk factors adjusted for age, sex, BMI categories and diseases. One hundred twenty-six were included in the study. Prevalence of low protein intake was 54 %. A greater day-to-day variation in protein intake was associated with low protein intake (adjusted OR 2·5; 95 % CI 1·14, 5·48). Participants with low protein intake had a higher prevalence of nausea, diarrhoea and mouth dryness. Reduced appetite, mouth dryness and pain increased odds of low protein intake (adjusted OR 3·06, 95 % CI 1·23, 7·63; OR 3·41, 95 % CI 1·51, 7·7; OR 1·54, 95 % CI 1·00, 2·36, respectively). There was a high prevalence of low protein intake in community-dwelling adults aged ≥ 80 years. Day-to-day variability, appetite, mouth dryness and pain may be potentially modifiable risk factors. Targeting dietary patterns and risk factors in primary prevention strategies may potentially improve intake of protein and minimise risk of physical frailty.

Wearable Focal Muscle Vibration on Pain, Balance, Mobility, and Sensation in Individuals with Diabetic Peripheral Neuropathy: A Pilot Study

People with diabetic peripheral neuropathy (DPN) experience a lower quality of life caused by associated pain, loss of sensation and mobility impairment. Current standard care for DPN is limited and lacking. This study explores the benefits of 4-week, in-home wearable focal muscle vibration (FMV) therapy on pain, balance, mobility, and sensation in people with DPN. Participants were randomized into three groups and received different FMV intensities. FMV was applied using a modified Myovolt^TM wearable device to the tibialis anterior, distal quadriceps, and gastrocnemius/soleus muscles on both lower limbs for three days a week over four weeks. The outcomes included pain, balance, mobility, sensation, device usage log, feedback survey, and a semi-structured interview. In all, 23 participants completed the study. The results showed significant improvement in average pain (Pre: 4.00 ± 2.29; Post: 3.18 ± 2.26; p = 0.007), pain interference with walking ability (Pre: 4.14 ± 3.20; Post: 3.09 ± 1.976; p = 0.03), and standard and cognitive Timed Up-and-Go scores (Pre: 13.75 ± 5.34; Post: 12.65 ± 5.25; p = 0.04; Pre: 15.12 ± 6.60; Post: 12.71 ± 5.57; p = 0.003, respectively); the overall pain improvement was trending towards significance (Pre: 3.48 ± 2.56; Post: 2.87 ± 1.85; p = 0.051). Balance and sensations improved but not significantly. There was a trend towards significance (p = 0.088), correlation (r = 0.382) between changes in balance and baseline pain. The participants were highly satisfied with wearable FMV and were 100% compliant. FMV therapy was associated with improved pain, mobility, and sensation. Further study with a larger sample and better outcome measures are warranted.

Patient- and Caregiver-Reported Burden of Transfusion-Dependent β-Thalassemia Measured Using a Digital Application

Background and Objective

Transfusion-dependent β-thalassemia (TDT) is a rare genetic disease characterized by a deficiency of functional β-globin, ultimately leading to lifelong dependence on blood transfusions. There is little patient- and caregiver-reported data with which to understand the holistic and societal impact of TDT. The objective of this study was to evaluate the patient- and caregiver-reported disease-management, symptom, and quality-of-life burden of TDT.

Methods

We conducted a prospective, observational, real-world study of adults with TDT and caregivers of adolescents with TDT, in Italy, the UK, and the USA. Over 90 days, participants used a smartphone application to respond to surveys about their or their dependent’s TDT, including bespoke background and disease-management surveys, the Brief Fatigue Inventory (BFI), the Transfusion-dependent Quality of life questionnaire (TranQol), and the Brief Pain Inventory Short Form (BPI-SF).

Results

Eighty-five individuals participated. Mean BFI and TranQol scores on enrollment were 5.0 (0–10 scale; 10 = worst symptoms) and 51 (0–100 scale; 100 = best quality of life), respectively. Mean transfusion frequency was every 3.2 weeks. Mean time spent on TDT management was 592 min on transfusion days and 91 min on non-transfusion days (11 h per week). Mean BFI and BPI-SF “worst fatigue” and “worst pain” scores were higher in the 5 days pre-transfusion than in the 5 days post-transfusion (fatigue 5.05 vs 4.29; pain 4.33 vs 3.85; 0–10 scale; 10 = worst symptoms).

Conclusions

The patient- and caregiver-reported burden of TDT is high, influenced by disease-management time, fatigue, pain, and quality-of-life impairment.

Electronic supplementary material

The online version of this article (10.1007/s40271-020-00473-0) contains supplementary material, which is available to authorized users.

A 3-way Cross-over Study of Pregabalin, Placebo, and the Histamine 3 Receptor Inverse Agonist AZD5213 in Combination With Pregabalin in Patients With Painful Diabetic Neuropathy and Good Pain-reporting Ability

OBJECTIVES

In this study, patients with painful diabetic neuropathy were trained using an experimental pain paradigm in an attempt to enroll a subset of patients who are "pain connoisseurs" and therefore more able to discriminate between active and placebo treatments.

METHODS

AZD5213, a novel histamine H3 receptor inverse agonist+pregabalin, pregabalin, and placebo were then tested in a 3-period cross-over.

RESULTS

The study did not provide any evidence of clinical efficacy for AZD5213 when combined with pregabalin in the treatment of painful diabetic neuropathy.

DISCUSSION

The training of study patients in pain reporting and subsequent enrichment with good pain reporters also did not enable the robust detection of the efficacy of pregabalin relative to placebo in a small sample size. Further work is required before recommending the use of "connoisseur" patients in future neuropathic pain studies.

Validation of Pain Assessment Checklist for Seniors with Limited Ability to Communicate-II (PACSLAC-II) in Iranian older adults with dementia living in nursing homes

BACKGROUND

Some dementia patients can self-report pain although the reports are not valid in severe dementia. Observational scales have been developed for pain assessment in these patients. This study aimed to assess the psychometric properties of the Persian version of Pain Assessment Checklist for Seniors with Limited Ability to Communicate-II (PACSLAC-II).

METHODS

This validation study was conducted on 138 older adults with dementia suffering from chronic pain who lived in nursing homes. The PACSLAC-II Persian version was applied through observations during activity and rest. Reliability of the PACSLAC-II was evaluated by Cronbach's alpha and intra-class correlation coefficients. Construct validity was determined by confirmatory factor analysis, divergent and convergent validity. The Spearman's rank correlation between PACSLAC-II scores and Faces Pain Scale was calculated for concurrent validity. Known-group validity during activity and rest was calculated by Wilcoxon signed ranks test.

RESULTS

Cronbach's alpha coefficient for facial expression (0.82), verbalisation (0.72), and body movement (0.84) subscales indicated good internal consistency. The intra-class correlation coefficients between two raters was 0.76 and in three times evaluation, the value was 0.76. Convergent validity with Iranian Brief Pain Inventory and divergent validity with 15-item Geriatric Depression Scale confirmed the construct validity of PACSLAC-II. Three factors structure of PACSLAC-II was approved, and most of the variance was explained by facial expressions. The PACSLAC-II can discriminate between pain and non-pain events and has a moderate correlation with Faces Pain Scale (r = 0.33).

CONCLUSIONS

PACSLAC-II Persian version is a valid and reliable scale for pain assessment in older adults with dementia.

Sex and Gender are Not the Same: Why Identity Is Important for People Living with HIV and Chronic Pain

Background

Sex differences in pain sensitivity have been well documented, such that women often report greater sensitivity than men. However, clinical reports highlighting sex differences often equate gender and sex. This is a particularly critical oversight for those whose gender identity is different than their genetic sex.

Methods

This preliminary study sets to analyze differences in pain responses between cisgender and transgender individuals living with HIV and chronic pain. A total of 51 African-American participants (24 cisgender men, 20 cisgender women, 7 transgender women) with similar socioeconomic status were recruited. Genetic sex, gender identity, depression and anxiety, pain severity, pain interference and pain-related stigma were recorded. Participants also completed a quantitative sensory testing battery to assess pain in response to noxious heat and mechanical stimuli.

Results

Transgender women and cisgender women demonstrated a greater magnitude of temporal summation for heat pain stimuli or mechanical stimuli compared to cisgender men. Specifically, transgender women reported greater mechanical summation than either cisgender women or cisgender men. Transgender women and cisgender women similarly reported greater chronic pain severity compared to cisgender men.

Conclusion

These data support the notion that gender identity may play a more significant role in pain sensation than genetic sex. These results further maintain that not only gender identity and genetic sex are distinct variables but that treatment should be based on identity as opposed to genetic sex.

Moderate to severe acute pain disturbs motor cortex intracortical inhibition and facilitation in orthopedic trauma patients: A TMS study

OBJECTIVE

Primary motor (M1) cortical excitability alterations are involved in the development and maintenance of chronic pain. Less is known about M1-cortical excitability implications in the acute phase of an orthopedic trauma. This study aims to assess acute M1-cortical excitability in patients with an isolated upper limb fracture (IULF) in relation to pain intensity.

METHODS

Eighty-four (56 IULF patients <14 days post-trauma and 28 healthy controls). IULF patients were divided into two subgroups according to pain intensity (mild versus moderate to severe pain). A single transcranial magnetic stimulation (TMS) session was performed over M1 to compare groups on resting motor threshold (rMT), short-intracortical inhibition (SICI), intracortical facilitation (ICF), and long-interval cortical inhibition (LICI).

RESULTS

Reduced SICI and ICF were found in IULF patients with moderate to severe pain, whereas mild pain was not associated with M1 alterations. Age, sex, and time since the accident had no influence on TMS measures.

DISCUSSION

These findings show altered M1 in the context of acute moderate to severe pain, suggesting early signs of altered GABAergic inhibitory and glutamatergic facilitatory activities.

The protocol for a multisite, double blind, randomized, placebo-controlled trial of axillary nerve stimulation for chronic shoulder pain

BACKGROUND

Shoulder impingement syndrome is one of the most common causes of shoulder pain, accounting for approximately 30% of all shoulder pain. Approximately 35% of patients with shoulder impingement syndrome are refractory to conservative treatment. For patients who fail conservative treatment, there is no established treatment to successfully treat their chronic pain. Prior randomized control trials have demonstrated efficacy for the use of a single lead intramuscular peripheral nerve stimulation of the axillary nerve at the motor points of the deltoid muscle for treatment of hemiplegic shoulder pain. This is the first controlled trial to utilize the same novel technology to treat shoulder impingement syndrome outside of the stroke population.

METHODS

This is a dual-site, placebo-controlled, double-blinded, randomized control trial. Participants will be randomized to two treatment groups. The intervention group will be treated with active peripheral nerve stimulation of the axillary nerve of the affected shoulder and the control group will be treated with sham peripheral nerve stimulation of the axillary nerve of the affected shoulder. Both groups will receive a standardized exercise therapy program directed by a licensed therapist.

DISCUSSION

This study protocol will allow the investigators to determine if this novel, non-pharmacologic treatment of shoulder pain can demonstrate the same benefit in musculoskeletal patients which has been previously demonstrated in the stroke population.

TRIAL REGISTRATION

Clinicaltrials.gov, NCT03752619. Registered on 26 November 2018.

High-frequency spinal cord stimulation at 10 kHz for the treatment of painful diabetic neuropathy: design of a multicenter, randomized controlled trial (SENZA-PDN)

BACKGROUND

Painful diabetic neuropathy (PDN), a debilitating and progressive chronic pain condition that significantly impacts quality of life, is one of the common complications seen with long-standing diabetes mellitus. Neither pharmacological treatments nor low-frequency spinal cord stimulation (SCS) has provided significant and long-term pain relief for patients with PDN. This study aims to document the value of 10-kHz SCS in addition to conventional medical management (CMM) compared with CMM alone in patients with refractory PDN.

METHODS

In a prospective, multicenter, randomized controlled trial (SENZA-PDN), 216 subjects with PDN will be assigned 1:1 to receive 10-kHz SCS combined with CMM or CMM alone after appropriate institutional review board approvals and followed for 24 months. Key inclusion criteria include (1) symptoms of PDN for at least 12 months, (2) average pain intensity of at least 5 cm-on a 0- to 10-cm visual analog scale (VAS)-in the lower limbs, and (3) an appropriate candidate for SCS. Key exclusion criteria include (1) large or gangrenous ulcers or (2) average pain intensity of at least 3 cm on VAS in the upper limbs or both. Along with pain VAS, neurological assessments, health-related quality of life, sleep quality, and patient satisfaction will be captured. The primary endpoint comparing responder rates (≥50% pain relief) and safety rates between the treatment groups will be assessed at 3 months. Several secondary endpoints will also be reported on.

DISCUSSION

Enrollment commenced in 2017 and was completed in 2019. This study will help to determine whether 10-kHz SCS improves clinical outcomes and health-related quality of life and is a cost-effective treatment for PDN that is refractory to CMM.

TRIAL REGISTRATION

ClincalTrials.gov identifier: NCT03228420 (registered 24 July 2017).

Efficacy and Safety of Low Doses of Trazodone in Patients Affected by Painful Diabetic Neuropathy and Treated with Gabapentin: A Randomized Controlled Pilot Study

BACKGROUND

Painful diabetic neuropathy is an important therapeutic challenge as the efficacy of analgesic drugs in this setting is still unsatisfactory. Monotherapy with available treatments is often not sufficient and a combination of drugs is necessary. Trazodone (TRZ) is a compound with a multi-modal mechanism of action, being a serotonin-2 antagonist/reuptake inhibitor developed and approved for the treatment of depression in several countries. Previous clinical trials suggest a possible beneficial effect of low doses of trazodone for the treatment of patients affected by painful diabetic neuropathy.

OBJECTIVE

This phase II study was designed to collect data on the efficacy and safety of low doses of TRZ combined with gabapentin after 8 weeks of treatment in patients affected by painful diabetic neuropathy.

METHODS

This was a randomized, double-blind, placebo-controlled, multi-center, international, prospective study. Male and female diabetic patients aged 18-75 years and affected by painful diabetic neuropathy were eligible for enrollment. Subjects were randomized (1:1:1 ratio) to TRZ30 (10 mg three times daily for 8 weeks) or TRZ60 (20 mg three times daily for 8 weeks) or placebo. Gabapentin as background therapy was administered in open-label conditions to all patients. The primary endpoint was the change from baseline of the Brief Pain Inventory Short Form item 5 to week 8. Secondary endpoints included the other Brief Pain Inventory Short Form items, and the assessment of anxiety, sleep, quality of life, patient's improvement, and safety.

RESULTS

One hundred and forty-one patients were included in the intention-to-treat population: 43 allocated to the TRZ30 group, 50 to the TRZ60 group, and 48 to the placebo group. After 8 weeks, the mean changes of Brief Pain Inventory Short Form item 5 from baseline were - 3.1, - 2.6, and - 2.5 in the TRZ30, TRZ60, and placebo groups, respectively. No statistically significant differences between groups were seen. Nevertheless, a better trend was observed for TRZ30 vs placebo (95% confidence interval - 1.30, 0.15; p = 0.1179), on top of the background effect of gabapentin administered to all study groups. 62.8% of patients achieved a ≥ 50% reduction in the TRZ30 group, 54% in the TRZ60 group, and 45.8% in the placebo group. At the same time, a statistically significant improvement was observed in Brief Pain Inventory Short Form item 6 for TRZ30 vs placebo (95% confidence interval - 1.54, - 0.07; p = 0.0314). No serious adverse event occurred during the trial and the most frequent treatment-emergent adverse events involved nervous system, QT prolongation, and gastrointestinal disorders.

CONCLUSIONS

All treatment groups showed a clinically meaningful pain improvement; nevertheless, patients in the TRZ30 treatment group reported better efficacy outcomes. This finding suggests that low doses of TRZ could be useful for treating painful diabetic neuropathy, and support further adequately powered confirmatory trials investigating the efficacy of TRZ.

CLINICAL TRIAL REGISTRATION

NCT03202979, date of registration: 29/06/2017.

Brief Pain Inventory: A proposal to extend its clinical application

BACKGROUND

This study presents an adaptation of the Brief Pain Inventory (BPI) extending its use in clinical/epidemiological contexts and the evaluation of the properties of BPI (short form) in a sample of Brazilian adults.

METHODS

Part of item 1 of this instrument was removed because it prevented the participation of individuals with usual pain. In addition to the reference period of original response "last 24 hr," a new period "last pain experience" was proposed. Individuals responded about the presence/lack and onset of pain. Individuals who reported pain in the last 24 hr before the interview answered the BPI considering both reference periods. Confirmatory factor analysis was performed to check the fit of five theoretical BPI models.

RESULTS

A total of 1,176 adults participated (79.0% women; 38.7 (SD = 10.8) years), 29.2% did not report pain in the last 24 hr, 33.6% reported pain <3 months and 37.2% pain ≥3 months. All theoretical BPI models presented adequate fit indices (GFI ≥ 0.9; RMSEA < 0.1; α ≥ 0.7) when both reference periods were used. In conclusion, the adaptations proposed can contribute to extend the use of BPI.

CONCLUSIONS

The reference period of responses and the theoretical model used must be chosen according to the needs of the researcher and/or physician.

SIGNIFICANCE

This study presents evidence related to the validity of applying the Brief Pain Inventory (BPI) in adults with and without pain considering the present pain or memory of pain, enabling the clinician to collect additional information that may be relevant to the clinical management of pain.

Enhanced facilitation and diminished inhibition characterizes the pronociceptive endogenous pain modulatory balance of persons living with HIV and chronic pain

Chronic pain in persons living with HIV (PLWH) may be related to alterations in endogenous pain modulatory processes (e.g., high facilitation and low inhibition of nociception) that promote exaggerated pain responses, known as hyperalgesia, and central nervous system (CNS) sensitization. This observational study examined differences in endogenous pain modulatory processes between 59 PLWH with chronic pain, 51 PLWH without chronic pain, and 50 controls without HIV or chronic pain. Quantitative sensory testing for temporal summation (TS) of mechanical and heat pain as well as conditioned pain modulation (CPM) were used to assess endogenous pain facilitatory and inhibitory processes, respectively. Associations among TS, CPM, and self-reported clinical pain severity were also examined in PLWH with chronic pain. Findings demonstrated significantly greater TS of mechanical and heat pain for PLWH with chronic pain compared to PLWH without chronic pain and controls. CPM effects were present in controls, but not in either PLWH with or without chronic pain. Among PLWH with chronic pain, greater TS of mechanical pain was significantly associated with greater average clinical pain severity. Results of this study suggest that enhanced facilitation and diminished inhibition characterizes the pronociceptive endogenous pain modulatory balance of persons living with HIV and chronic pain.

Living with painful diabetic neuropathy: insights from focus groups into fears and coping strategies

OBJECTIVE

Painful diabetic neuropathy (PDN) is known to negatively affect quality of life. Being physically active is a crucial part of successful diabetes self-management, but regimen adherence is often low. Coping strategies and fears have shown to be related to less physical activity (PA). The aim of the present study was to obtain more in-depth information on psychological risk factors leading to less PA in persons with PDN.

DESIGN

Three semi-structured focus group interviews were conducted with a representative sample of persons with PDN (N = 12). Data were transcribed verbatim and analysed using a hybrid method of thematic analyses and a grounded theory approach.

MAIN OUTCOME MEASURES

Fears and coping strategies related to PA in persons with PDN.

RESULTS

Several specific fears were identified; fear of hypoglycaemia, fear of pain increase, fear of total exhaustion, fear of physical injury, fear of falling, fear of loss of identity, and fear of negative evaluation by others. To cope with these fears, avoidance, remaining active, cognitive distraction, and acceptance strategies were described.

CONCLUSION

In persons with PDN, diabetes-related fears and pain-related fears play a role in less engagement in PA, indicating the need for new methods for improving self-management in persons with PDN.

An Assessment of Clinically Important Differences on the Worst Pain Severity Item of the Modified Brief Pain Inventory in Patients with Diabetic Peripheral Neuropathic Pain

Objectives

Using patient global impression of change (PGIC) as an anchor, an approximately 30% reduction on an 11-point numeric pain intensity rating scale (PI-NRS) is considered a clinically important difference (CID) in pain. Our objective was to define the CID for another pain measure, the worst pain severity (WPS) item of the modified Brief Pain Inventory (m-BPI).

Methods

In this post hoc analysis of a double-blind, placebo-controlled, phase 2 study, 452 randomized patients with diabetic peripheral neuropathic pain (DPNP) were followed over 5 weeks, with m-BPI data collected weekly and PGIC at treatment conclusion. Receiver operating characteristic (ROC) curves (via logistic regression) were used to determine the changes in the m-BPI-WPS score that best predicted ordinal clinical improvement thresholds (i.e., "minimally improved" or better) on the PGIC.

Results

Similar to the PI-NRS, a change of -3 (raw) or -33.3% from the baseline on the m-BPI-WPS optimized prediction for the "much improved" or better PGIC threshold and represents a CID. There was a high correspondence between observed and predicted PGIC categories at each PGIC threshold (ROC AUCs were 0.78-0.82).

Conclusions

Worst pain on the m-BPI may be used to assess clinically important improvements in DPNP studies. Findings require validation in larger studies.

Intersectional health-related stigma in persons living with HIV and chronic pain: implications for depressive symptoms

"Intersectional health-related stigma" (IHRS) refers to stigma that arises at the convergence of multiple health conditions. People living with HIV (PLWH) and chronic pain have two highly stigmatized health conditions, and thus may be at especially high risk for internalizing these stigmas and consequently experiencing depression. This study examined the intersectionality of internalized HIV and chronic pain stigma in relation to depressive symptoms in a sample of PLWH and chronic pain. Sixty participants were recruited from an HIV clinic in the Southeastern United States. Chronic pain was defined as pain that has been present for at least three consecutive months, and that has been an ongoing problem for at least half the days in the past six months. All participants completed the HIV Stigma Mechanisms Scale, Internalized Stigma in Chronic Pain Scale, the Short-Form Brief Pain Inventory, and the Center for Epidemiological Studies - Depression Scale. Clinical data was collected from medical records. An intersectional HIV and chronic pain composite variable was created and participants were categorized as either high (28%), moderate (32%), or low (40%). Results revealed that intersectional HIV and chronic pain stigma was significantly associated with severity of depressive symptoms (p = .023). Pairwise contrasts revealed that participants with high (p = .009) and moderate (p = .033) intersectional stigma reported significantly greater mean depressive symptom severity than those with low intersectional stigma. Participants who reported the highest levels of internalized HIV and chronic pain stigma also reported the greatest severity of depressive symptoms. This suggests that the experience of both HIV and chronic pain stigma (i.e., IHRS) among PLWH and chronic pain may synergistically perpetuate negative mood in a more profound manner than experiencing either one stigma alone.

Diabetic Peripheral Neuropathy: Epidemiology, Diagnosis, and Pharmacotherapy

PURPOSE

Diabetic peripheral neuropathy (DPN) is the commonest cause of neuropathy worldwide, and its prevalence increases with the duration of diabetes. It affects approximately half of patients with diabetes. DPN is symmetric and predominantly sensory, starting distally and gradually spreading proximally in a glove-and-stocking distribution. It causes substantial morbidity and is associated with increased mortality. The unrelenting nature of pain in this condition can negatively affect a patient's sleep, mood, and functionality and result in a poor quality of life. The purpose of this review was to critically review the current literature on the diagnosis and treatment of DPN, with a focus on the treatment of neuropathic pain in DPN.

METHODS

A comprehensive literature review was undertaken, incorporating article searches in electronic databases (EMBASE, PubMed, OVID) and reference lists of relevant articles with the authors' expertise in DPN. This review considers seminal and novel research in epidemiology; diagnosis, especially in relation to novel surrogate end points; and the treatment of neuropathic pain in DPN. We also consider potential new pharmacotherapies for painful DPN.

FINDINGS

DPN is often misdiagnosed and inadequately treated. Other than improving glycemic control, there is no licensed pathogenetic treatment for diabetic neuropathy. Management of painful DPN remains challenging due to difficulties in personalizing therapy and ascertaining the best dosing strategy, choice of initial pharmacotherapy, consideration of combination therapy, and deciding on defining treatment for poor analgesic responders. Duloxetine and pregabalin remain first-line therapy for neuropathic pain in DPN in all 5 of the major published guidelines by the American Association of Clinical Endocrinologists, American Academy of Neurology, European Federation of Neurological Societies, National Institute of Clinical Excellence (United Kingdom), and the American Diabetes Association, and their use has been approved by the US Food and Drug Administration.

IMPLICATIONS

Clinical recognition of DPN is imperative for allowing timely symptom management to reduce the morbidity associated with this condition.

Effect of α-lipoic acid on symptoms and quality of life in patients with painful diabetic neuropathy

Objective

To examine the effect of α-lipoic acid on neuropathic symptoms in patients with diabetic neuropathy (DN).

Methods

Patients with painful DN were treated with 600 mg/day α-lipoic acid, orally, for 40 days. Neuropathy Symptom Score (NSS), Subjective Peripheral Neuropathy Screen Questionnaire (SPNSQ) and douleur neuropathique (DN)4 questionnaire scores were assessed at baseline and day 40. Quality-of-life treatment effects were assessed by Brief Pain Inventory (BPI), Neuropathic Pain Symptom Inventory (NPSI) and Sheehan Disability Scale (SDS). Changes in body weight, arterial blood pressure, fasting serum glucose and lipids were also assessed.

Results

Out of 72 patients included, significant reductions in neuropathic symptoms were shown by reduced NSS, SPNSQ and DN4 scores at day 40 versus baseline. BPI, NPSI, and SDS in terms of work disability, social life disability, and family life disability scores were also significantly reduced. Moreover, 50% of patients rated their health condition as ‘very much better’ or ‘much better’ following α-lipoic acid administration. Fasting triglyceride levels were reduced, but no difference was found in body weight, blood pressure, fasting glucose, or other lipids at day 40 versus baseline.

Conclusions

A-lipoic acid administration was associated with reduced neuropathic symptoms and triglycerides, and improved quality of life.

Symptoms as Patient-Reported Outcomes in Cancer Patients Undergoing Immunotherapies

Cancer therapies are toxic. Newer oncological treatments such as immunotherapy produce unconventional adverse events that are collectively referred to as immune-related adverse events (irAEs). These irAEs are clinician-rated and typically reported via tabulation of adverse events from the National Cancer Institute's Common Terminology Criteria for Adverse Events (CTCAE). However, the symptomatic effects of treatment and the severity of disease are best reported by the patient themselves. Although many pivotal trials for immunotherapeutic agents include health-related quality-of-life measures, symptom-focused assessments are more proximal to the effects of treatment and disease burden. This chapter discusses how best to measure symptoms, describes the desirable properties of a psychometrically valid symptom assessment tool, reviews available symptom assessment tools, provides methods to assist in the interpretation of PRO data, elucidates the feasibility and benefit of incorporating PRO in several cancer cohorts, describes the current use of PROs in immunotherapy, and identifies areas where further research are needed to enhance the use of PROs in cancer patients undergoing immunotherapy.

Randomized Trial of the Effect of Mindfulness-Based Stress Reduction on Pain-Related Disability, Pain Intensity, Health-Related Quality of Life, and A1C in Patients With Painful Diabetic Peripheral Neuropathy

IN BRIEF Painful diabetic peripheral neuropathy (PDPN) has a large negative impact on patients' physical and mental functioning, and pharmacological therapies rarely provide more than partial relief. Mindfulness-based stress reduction (MBSR) is a group psychosocial intervention that was developed for patients with chronic illness who were not responding to existing medical treatments. This study tested the effects of community-based MBSR courses for patients with PDPN. Among patients whose PDPN pharmacotherapy had been optimized in a chronic pain clinic, those randomly assigned to treatment with MBSR experienced improved function, better health-related quality of life, and reduced pain intensity, pain catastrophizing, and depression compared to those receiving usual care.

Validity and reliability of a Turkish Brief Pain Inventory Short Form when used to evaluate musculoskeletal pain

BACKGROUND

The Brief Pain Inventory (BPI) is both a questionnaire and an outcome measure that is used widely in clinical trials to assess pain associated with many conditions. The BPI Short Form has been extensively translated into foreign languages. The aim of this study was to assess the validity and reliability of a Turkish Brief Pain Inventory Short Form (BPI-TR) to evaluate musculoskeletal pain.

METHODS

In total, 297 patients with musculoskeletal pain participated in the study. Demographic characteristics and brief medical histories were recorded. Pain intensity was assessed using a visual analogue scale (VAS) and quality-of-life was assessed using the Short Form 36 (SF-36). Pain was evaluated using the BPI-TR in all patients. Internal consistency and test-retest analysis were used to assess reliability. The internal consistency of the scale items was assessed by calculating Cronbach's α value, which was expected to be > 0.7. The criterion validity of the BPI-TR was assessed by correlation with VAS scores.

RESULTS

Pain intensity, pain interference, and other components of the Turkish version were consistent with validity thereof. Cronbach's α was 0.84 for pain intensity and 0.89 for pain interference. The extent of BPI-TR and VAS correlation was statistically significant.

CONCLUSIONS

The BPI-TR may be used for assessment of musculoskeletal pain.

Physical pain is common and associated with nonmedical prescription opioid use among people who inject drugs

Background

People who inject drugs (PWID) often have poor health and lack access to health care. The aim of this study was to examine whether PWID engage in self-treatment through nonmedical prescription opioid use (NMPOU). We describe the prevalence and features of self-reported physical pain and its association with NMPOU.

Methods

PWID (N = 702) in San Francisco, California (age 18+) were recruited to complete interviewer administered surveys between 2011 and 2013. Multivariate logistic regression analysis was conducted to examine the associations among self-reported pain dimensions (past 24-h average pain, pain interference with functional domains) and NMPOU, controlling for age, sex, psychiatric illness, opioid substitution treatment, homelessness, street heroin use and unmet healthcare needs.

Results

Almost half of the sample reported pain, based on self-reported measures in the 24 h before their interview. The most common pain locations were to their back and lower extremities. Past 24-h NMPOU was common (14.7%) and associated with past 24 h average pain intensity on a 10 point self-rating scale (adjusted odds ratio [AOR] = 2.15, 95% confidence interval [CI] 1.21–3.80), and past 24 h pain interference with general activity (AOR 1.82 [95% CI 1.04–3.21]), walking ability (AOR 2.52 [95% CI 1.37–4.63]), physical ability (AOR 2.01 [95% CI 1.16–3.45]), sleep (AOR 1.98 [95% CI 1.13–3.48]) and enjoyment of life (AOR 1.79 [95% CI 1.02–3.15]).

Conclusion

Both pain and NMPOU are common among PWID, and highly correlated in this study. These findings suggest that greater efforts are needed to direct preventive health and services toward this population.

Low back pain in healthy postmenopausal women and the effect of physical activity: A secondary analysis in a randomized trial

Epidemiological studies on the prevalence of musculoskeletal pain have consistently shown that this is a relevant health problem, with non-specific low back pain (LBP) being the most commonly reported in adult females. Conflicting data on the association between LBP symptoms and physical activity (PA) have been reported. Here, we investigated the prevalence of LBP and the effect of a 24-month non-specific PA intervention on changes in LBP prevalence in a series of Italian healthy postmenopausal women. We performed a secondary analysis in the frame of the DAMA trial, a factorial randomized intervention trial aimed to evaluate the ability of a 24-month intervention, based on moderate-intensity PA, and/or dietary modification, in reducing mammographic breast density in healthy postmenopausal women. The PA intervention included at least 1 hour/day of moderate PA and a more strenuous weekly activity, collective walks and theoretical group sessions. A self-administered pain questionnaire was administered at baseline and at the end of the intervention. The questionnaire was specifically structured to investigate the occurrence of musculoskeletal pain, the body localization, intensity and duration of the pain. Two hundred and ten women (102 randomized to PA intervention, 108 not receiving the PA intervention) filled out the questionnaires. At baseline LBP was present in 32.9% of the participants. Among women randomized to the PA intervention, LBP prevalence at follow up (21.6%) was lower than at baseline (33.3%) (p = 0.02), while in women who did not receive the PA intervention the LBP prevalence at baseline and follow up were 32.4% and 25.9%, respectively (p = 0.30). Overall, there was no significant between-group effect of PA intervention on LBP. Further studies are needed to understand the role of non-specific PA intervention, aimed to improve overall fitness, on LBP prevalence.

Methodology for self-report of rest pain (or spontaneous pain) vs evoked pain in chronic neuropathic conditions: a prospective observational pilot study

This pilot study provides evidence supporting the feasibility and validity of new self-report methodology for the assessment of rest vs evoked pain in chronic neuropathic conditions. Future confirmatory studies will further expand this field and facilitate important improvements in the research and development of new treatments for chronic pain.

Introduction:

The distinction between pain at rest and pain evoked by touch or movement has important clinical implications and may be associated with different mechanisms. However, current methods of clinical pain assessment pay little attention to directly distinguishing between these contrasting components of symptom burden.

Objectives:

We developed the 10-item “Functional Impact of Neuropathic Evoked and Spontaneous Symptom Evaluation” questionnaire designed to distinguish between rest and evoked pain.

Methods:

A prospective observational pilot study of this questionnaire was conducted in 78 participants with neuropathic pain diagnoses. Other study measures included the self-report version of the Leeds Assessment of Neuropathic Symptoms and Signs questionnaire and a modified Brief Pain Inventory. Exploratory analyses were conducted to evaluate the validity of the Functional Impact of Neuropathic Evoked and Spontaneous Symptom Evaluation questionnaire.

Results:

Pain symptoms often/very often/always (1) evoked by touch or movement, and (2) occurring at rest without tactile stimulation were reported by 81% and 65%, respectively. Evoked pain was associated with walking (64%) and standing (35%); and rest pain was associated with watching television (47%), reading (37%), and sitting (36%). Participants reporting both rest and evoked pain tended to report higher levels of pain interference compared to those reporting evoked pain only.

Discussion:

These results provide support for the feasibility and validity of new patient-report methods to distinguish between rest pain and evoked pain in chronic neuropathic conditions. Future studies are needed to confirm the reliability and validity of these methods, which may facilitate important improvements in the research and development of new treatments for chronic pain.

Evaluating the Measurement Properties of the Self-Assessment of Treatment Version II, Follow-Up Version, in Patients with Painful Diabetic Peripheral Neuropathy

Background. The Self-Assessment of Treatment version II (SAT II) measures treatment-related improvements in pain and impacts and impressions of treatment in neuropathic pain patients. The measure has baseline and follow-up versions. This study assesses the measurement properties of the SAT II. Methods. Data from 369 painful diabetic peripheral neuropathy (PDPN) patients from a phase III trial assessing capsaicin 8% patch (Qutenza®) efficacy and safety were used in these analyses. Reliability, convergent validity, known-groups validity, and responsiveness (using the Brief Pain Inventory-Diabetic Neuropathy [BPI-DN] and Patient Global Impression of Change [PGIC]) analyses were conducted, and minimally important differences (MID) were estimated. Results. Exploratory factor analysis supported a one-factor solution for the six impact items. The SAT II has good internal consistency (Cronbach's alpha: 0.96) and test-retest reliability (intraclass correlation coefficients: 0.62–0.88). Assessment of convergent validity showed moderate to strong correlations with change in other study endpoints. Scores varied significantly by level of pain intensity and sleep interference (p < 0.05) defined by the BPI-DN. Responsiveness was shown based on the PGIC. MID estimates ranged from 1.2 to 2.4 (pain improvement) and 1.0 to 2.0 (impact scores). Conclusions. The SAT II is a reliable and valid measure for assessing treatment improvement in PDPN patients.

Activity for Diabetic Polyneuropathy (ADAPT): Study Design and Protocol for a 2-Site Randomized Controlled Trial

BACKGROUND

Half of all patients with diabetes develop diabetic peripheral neuropathy (DPN), a complication leading to reduced mobility and quality of life. Although there are no proven pharmacologic approaches to reduce DPN risk or slow its progression, evidence suggests that physical activity may improve symptoms and enhance peripheral nerve regeneration.

OBJECTIVE

The aim of the study will be to determine the impact of an intense lifestyle intervention on neuropathy progression and quality of life in individuals with DPN.

DESIGN

The study will be a randomized controlled trial.

SETTING

The study will be conducted at 2 academic medical centers.

PARTICIPANTS

The participants will be 140 individuals with type 2 diabetes and mild to moderate DPN.

INTERVENTION

The intervention group will receive 18 months of supervised exercise training, actigraphy-based counseling to reduce sedentary behavior, and individualized dietary counseling. Control group participants will receive diet and activity counseling at baseline and at 9 months.

MEASUREMENTS

The primary outcomes are neuropathy progression as measured by intraepidermal nerve fiber density in a distal thigh skin biopsy and the Norfolk Quality of Life-Diabetic Neuropathy score. Secondary outcomes include pain, gait, balance, and mobility measures.

LIMITATIONS

Due to the combined intervention approach, this protocol will not be able to determine which intervention components influence outcomes. There also may be difficulty with participant attrition during the 18-month study intervention.

CONCLUSIONS

The Activity for Diabetic Polyneuropathy (ADAPT) protocol resulted from a collaboration between physical therapists and neurologist researchers that includes as primary outcomes both a quality-of-life measure (NQOL-DN) and a physiologic biomarker (IENFD). It has the potential to demonstrate that an intensive lifestyle intervention may be a sustainable, clinically effective approach for people with DPN that improves patient outcomes and can have an immediate impact on patient care and future clinical trials.

A study on comparative efficacy and cost effectiveness of Pregabalin and Duloxetine used in diabetic neuropathic pain

AIM

The study was designed for comparing the efficacy and cost effectiveness of Pregabalin and Duloxetine used in Diabetic Neuropathic Pain.

METHODS

The prospective interventional 6 month study was conducted in a diabetic clinic of a 500 bedded tertiary care hospital in South India. The subjects having diagnosed with diabetic neuropathy and not treated with Pregabalin and Duloxetine or any other drugs of its class were selected. The data were collected using NPS and Neuro QoL questionnaires. The cost of both drugs used in the study was calculated as the mean of the price of 3 leading common brands of those drugs. The comparative efficacy was calculated by comparing the mean difference produced by both drugs in NPS and QoL scores. The cost effectiveness were calculated by ICER ratio.

RESULTS

The results have shown a significant improvement in the mean difference of NPS and Neuro QoL scores of both Pregabalin (p=<0.001) and Duloxetine (p=<0.001) before and after the therapy, the Duloxetine dominates over Pregabalin in both. The mean cost of Pregabalin for 3 months therapy was found to be INR 668.7 and that for Duloxetine was INR 756. Duloxetine showed a better effect but more expensive. ICER ratio was calculated and found that a cost of INR 61.47 per extra QoL gained by Duloxetine.

CONCLUSION

The study have revealed that, both drugs are found to be effective.On conducting cost effective analysis, a significant better improvement in QoL of patients was obtained by Duloxetine with comparatively mild increase in the price.

Clinical Phenotype of Diabetic Peripheral Neuropathy and Relation to Symptom Patterns: Cluster and Factor Analysis in Patients with Type 2 Diabetes in Korea

OBJECTIVES

Patients with diabetic peripheral neuropathy (DPN) is the most common complication. However, patients are usually suffering from not only diverse sensory deficit but also neuropathy-related discomforts. The aim of this study is to identify distinct groups of patients with DPN with respect to its clinical impacts on symptom patterns and comorbidities.

METHODS

A hierarchical cluster analysis and factor analysis were performed to identify relevant subgroups of patients with DPN (n = 1338) and symptom patterns.

RESULTS

Patients with DPN were divided into three clusters: asymptomatic (cluster 1, n = 448, 33.5%), moderate symptoms with disturbed sleep (cluster 2, n = 562, 42.0%), and severe symptoms with decreased quality of life (cluster 3, n = 328, 24.5%). Patients in cluster 3, compared with clusters 1 and 2, were characterized by higher levels of HbA1c and more severe pain and physical impairments. Patients in cluster 2 had moderate pain levels but disturbed sleep patterns comparable to those in cluster 3. The frequency of symptoms on each item of MNSI by "painful" symptom pattern showed a similar distribution pattern with increasing intensities along the three clusters.

CONCLUSIONS

Cluster and factor analysis endorsed the use of comprehensive and symptomatic subgrouping to individualize the evaluation of patients with DPN.

Translation and Validation of the Thai Version of a Modified Brief Pain Inventory: A Concise Instrument for Pain Assessment in Postoperative Cardiac Surgery

BACKGROUND

Acute pain after cardiac surgery can be assessed using validated instruments such as the modified interference subscale of the Brief Pain Inventory (mod-BPI). Despite the available knowledge, the Thai version of a mod-BPI has not yet been presented.

OBJECTIVES

To translate a mod-BPI into the Thai language (BPI-T) and to validate it in acute pain after cardiac surgery.

METHODS

This multisetting, cross-sectional study was done from 4 cardiac centers. With a convenience sampling technique, 132 cardiac surgery patients were enrolled during the first 72 postoperative hours. A BPI-T composed of 4 items on the intensity subscale and 6 items on the interference subscale was translated following Brislin's model. Convergent validity against the numeric rating scale (NRS), confirmatory factor analysis (CFA), and internal consistency reliability were examined.

RESULTS

Of the total sample, 70% experienced moderate to severe pain (cutoff points of worst pain ≥ 4/10), and 65% had moderate to severe interference with deep breathing and coughing, 53% with general activity, and 49% with walking. The CFA confirmed the 2-factor structure of intensity and interference subscales consistent with the original version (root-mean-square error of approximation = 0.08, comparative fit index = 0.95, χ² = 39.00, df = 27, χ² /df = 1.44, P = 0.06). The physical and mental subdimensions under the interference subscale were determined (standardized factor loading = 0.70 and 0.42, respectively). The BPI-T also has good internal consistency (Cronbach's alpha coefficients 0.76 and 0.85). Pearson's correlation coefficients at 0.35 to 0.70 supported the convergent validity to the NRS.

CONCLUSIONS

The BPI-T is a concise instrument for pain assessment in postoperative cardiac surgery.

Capsaicin 8% Patch in Painful Diabetic Peripheral Neuropathy: A Randomized, Double-Blind, Placebo-Controlled Study

This 12-week study evaluated the efficacy and safety of capsaicin 8% patch versus placebo patch in painful diabetic peripheral neuropathy (PDPN). Patients aged 18 years or older with PDPN were randomized (1:1) to one 30-minute treatment (capsaicin 8% patch or placebo patch) to painful areas of the feet. Overall, 369 patients were randomized (capsaicin 8% patch, n = 186; placebo patch, n = 183). Percentage reduction in average daily pain score from baseline to between weeks 2 through 8 (the primary end point) was statistically significant for capsaicin 8% patch versus placebo (-27.4% vs -20.9%; P = .025); improvements in pain were observed from week 2 onward. Versus placebo, patients treated with capsaicin 8% patch had a shorter median time to treatment response (19 vs 72 days) and modest improvements in sleep interference scores from baseline to between weeks 2 through 8 (P = .030) and weeks 2 through 12 (P = .020). Apart from application site reactions, treatment-emergent adverse events were similar between groups. No indications of deterioration in sensory perception of sharp, cold, warm, or vibration stimuli were observed. In patients with PDPN, capsaicin 8% patch treatment provided modest pain relief and sleep quality improvements versus a placebo patch, similar in magnitude to other treatments with known efficacy, but without systemic side effects or sensory deterioration.

PERSPECTIVE

To our knowledge, this is the first study of the capsaicin 8% patch versus placebo in patients with PDPN to show that one 30-minute capsaicin treatment provides modest improvements in pain and sleep quality. Results confirm the clinical utility of the capsaicin 8% patch in the diabetic population.

Recognition and management of psychosocial issues in diabetic neuropathy

Although psychosocial aspects of diabetic neuropathy (DN) have received far less attention than biological aspects, research conducted over the last decade has begun to illuminate several important pathways between DN and psychosocial outcomes, including depression, anxiety, and self-management of diabetic foot ulcer (DFU)-risk. Growing body of evidence indicates that DN is a risk factor for depression predicting both the severity and increments in depression over time. Whereas painful DN contributes to depression, postural instability is the DN symptom with the strongest, cumulative effect on depression. Furthermore, depression and foot self-care, while having no impact on the development of recurrent diabetic foot ulcers (DFU), play a substantial role in incident first DFU. Patient common sense misconceptions about DFU risks and associated emotional responses play an important role in shaping foot self-care. Depression, and especially DFU-specific emotions, may be linked to DFU chronicity through biological and behavioral pathways that are at present under investigation in several ongoing trials. Integrative approaches that target psychological factors such as anxiety and depression while concurrently optimizing treatment and self-management may therefore be most powerful. Cognitive behavioral therapy-based techniques that are informed by these findings deserve investigation.

Independent Risk Factors for Positive and Negative Symptoms in Patients with Diabetic Polyneuropathy

Patients with diabetes occasionally develop diabetic polyneuropathy (DPN), which is characterized by both positive symptoms such as pain and negative symptoms such as numbness/dysesthesia. However, these symptoms have always been collectively analyzed to determine their risk factors. This study aimed to independently analyze the risk factors for neuropathic pain and numbness/dysesthesia in DPN patients. In total, 298 patients with diabetes (age: 61.1 ± 10.4 years; 176 male) were included. The relationships among the incidence of DPN and its clinical parameters were determined using logistic regression models. Then, the statistical model was applied in two groups of DPN patients: those with pain only or both pain and the negative symptoms (pain group; n = 25) and those with the negative symptoms only or both pain and the negative symptoms (numbness/dysesthesia group; n = 60). All logistic regression models were adjusted for the duration of diabetes, glycosylated hemoglobin levels, and age. The depression score was higher for patients with DPN than for those without, although it did not reach an abnormal level. An abnormal Achilles tendon reflex (ATR) and insulin treatment, but not smoking, hypertension, hyperlipidemia, and diabetic retinopathy, were associated with DPN. Furthermore, female sex and an abnormal ATR and insulin treatment were significant clinical features in the pain and numbness/numbness groups, respectively. Overweight and obesity were the common clinical features in both groups. We conclude that the positive and negative symptoms of DPN possibly have independent risk factors, suggesting different underlying mechanisms and the need for separate diagnosis and treatment.