Pathogenesis, diagnosis and clinical management of diabetic sensorimotor peripheral neuropathy.

Diabetic sensorimotor peripheral neuropathy (DSPN) is a serious complication of diabetes mellitus and is associated with increased mortality, lower-limb amputations and distressing painful neuropathic symptoms (painful DSPN). Our understanding of the pathophysiology of the disease has largely been derived from animal models, which have identified key potential mechanisms. However, effective therapies in preclinical models have not translated into clinical trials and we have no universally accepted disease-modifying treatments. Moreover, the condition is generally diagnosed late when irreversible nerve damage has already taken place. Innovative point-of-care devices have great potential to enable the early diagnosis of DSPN when the condition might be more amenable to treatment. The management of painful DSPN remains less than optimal; however, studies suggest that a mechanism-based approach might offer an enhanced benefit in certain pain phenotypes. The management of patients with DSPN involves the control of individualized cardiometabolic targets, a multidisciplinary approach aimed at the prevention and management of foot complications, and the timely diagnosis and management of neuropathic pain. Here, we discuss the latest advances in the mechanisms of DSPN and painful DSPN, originating both from the periphery and the central nervous system, as well as the emerging diagnostics and treatments.

Pain in Patients With Type 2 Diabetes-Related Polyneuropathy Is Associated With Vascular Events and Mortality.

PURPOSE: Type 2 diabetes-related polyneuropathy (DPN) is associated with increased vascular events and mortality, but determinants and outcomes of pain in DPN are poorly understood. We sought to examine the effect of neuropathic pain on vascular events and mortality in patients without DPN, DPN with pain (DPN + P), and DPN without pain (DPN-P). METHODS: A retrospective cohort study was conducted within a large health system of adult patients with type 2 diabetes from January 1, 2009 through December 31, 2016. Using an electronic algorithm, patients were classified as no DPN, DPN + P, or DPN-P. Primary outcomes included number of vascular events and time to mortality. Independent associations with DPN + P were evaluated using multivariable negative binomial and Cox proportional hazards regression models, adjusting for demographics, socioeconomic characteristics, and comorbidities. RESULTS: Of 43 945 patients with type 2 diabetes (age 64.6 ±â€…14.0 years; 52.1% female), 13 910 (31.7%) had DPN: 9104 DPN + P (65.4%) vs 4806 DPN-P (34.6%). Vascular events occurred in 4538 (15.1%) of no DPN patients, 2401 (26.4%) DPN + P, and 1006 (20.9%) DPN-P. After adjustment, DPN + P remained a significant predictor of number of vascular events (incidence rate ratio [IRR] = 1.55, 95% CI, 1.29-1.85), whereas no DPN was protective (IRR = 0.70, 95% CI, 0.60-0.82), as compared to DPN-P. Compared to DPN-P, DPN + P was also a significant predictor of mortality (hazard ratio = 1.42, 95% CI, 1.25-1.61). CONCLUSIONS: Our study found a significant association between pain in DPN and an increased risk of vascular events and mortality. This observation warrants longitudinal study of the risk factors and natural history of pain in DPN.

Gabapentin dose and the 30-day risk of altered mental status in older adults: A retrospective population-based study.

Gabapentin is an effective treatment for chronic neuropathic pain but may cause dizziness, drowsiness, and confusion in some older adults. The goal of this study was to assess the association between gabapentin dosing and adverse outcomes by obtaining estimates of the 30-day risk of hospitalization with altered mental status and mortality in older adults (mean age 76 years) in Ontario, Canada initiated on high dose (>600 mg/day; n = 34,159) compared to low dose (≤600 mg/day; n = 76,025) oral gabapentin in routine outpatient care. A population-based, retrospective cohort study assessing new gabapentin use between 2002 to 2014 was conducted. The primary outcome was 30-day hospitalization with an urgent head computed tomography (CT) scan in the absence of evidence of stroke (a proxy for altered mental status). The secondary outcome was 30-day all-cause mortality. The baseline characteristics measured in the two dose groups were similar. Initiation of a high versus low dose of gabapentin was associated with a higher risk of hospitalization with head CT scan (1.27% vs. 1.06%, absolute risk difference 0.21%, adjusted relative risk 1.29 [95% CI 1.14 to 1.46], number needed to treat 477) but not a statistically significant higher risk of mortality (1.25% vs. 1.16%, absolute risk difference of 0.09%, adjusted relative risk of 1.01 [95% CI 0.89 to 1.14]). Overall, the risk of being hospitalized with altered mental status after initiating gabapentin remains low, but may be reduced through the judicious use of gabapentin, use of the lowest dose to control pain, and vigilance for early signs of altered mental status.

Living with advanced but stable multiple myeloma: a study of the symptom burden and cumulative effects of disease and intensive (hematopoietic stem cell transplant-based) treatment on health-related quality of life.

CONTEXT: The cumulative impact of disease and treatment-related factors on health-related quality of life (HRQoL) in long-term survivors of multiple myeloma is poorly characterized. OBJECTIVES: To characterize HRQoL and symptom burden in advanced, intensively treated myeloma. METHODS: We performed detailed assessments in patients who had undergone hematopoietic stem cell transplantation and subsequent treatment for at least one episode of progressive disease. To exclude the impact of active disease and acute toxicity of treatment, patients were in a stable plateau phase. Patients were assessed for HRQoL (Short Form-12, European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Core 30, and Multiple Myeloma Module), pain (Brief Pain Inventory-Short Form), peripheral neuropathy (self-report Leeds Assessment of Neuropathic Symptoms and Signs), and concerns (adapted from Profile of Concerns). Serum interleukin-6 and tumor necrosis factor-alpha were measured. RESULTS: A total of 32 patients were enrolled, with a median age of 55 years at diagnosis and 60 years at assessment. After a median 5.5 years from diagnosis and three lines of treatment, physical functioning was significantly compromised (P<0.001) and associated with progressive work disability and concerns regarding loss of independence. Fatigue and pain were the predominant symptoms, impacting negatively on physical functioning (P<0.001). Pain was predominantly neuropathic in half the patients. Serum interleukin-6 levels positively correlated with pain (P=0.03), pain interference (P=0.003), insomnia (P=0.02), and appetite loss (P=0.02), and inversely correlated with physical functioning (P=0.03). CONCLUSION: Despite disease control and supportive care, intensively treated long-term myeloma survivors have significantly compromised HRQoL related to symptom burden. Systematic assessment is routinely indicated in advanced phase myeloma, even when disease activity is stable. Further studies should investigate the utility of interventional strategies and the relationship of cytokines with symptoms.

Pain in end-stage renal disease: a frequent and neglected clinical problem.

Pain is a major health problem in end-stage renal disease (ESRD) affecting half of the dialysis patients; most of them experience a moderate to severe degree of pain. Nevertheless, the impact of chronic pain and its consequences are often underestimated. Sources of pain related to the uremic environment are renal bone disease (osteitis fibrosa cystica, amyloidosis, osteomalacia), osteoarthritis, calcific uremic arteriolopathy and peripheral neuropathy. Moreover, comorbid conditions such as ischemic peripheral artery disease, diabetic neuropathy, osteopenia/ osteoporosis (due to long-standing hypertension, diabetes, or old age) result in various kinds of pain. Also the primary kidney disease (e.g. autosomal dominant polycystic kidney disease (ADPKD)) as well as performance of hemodialysis or peritoneal dialysis are important causes of pain. Potential consequences of persistent pain are disturbed sleep, weakened memory/attention, altered mood (anxiety and depressive disorder), impotence, poorer physical state, less social activities and consideration of withdrawal from dialysis. Consequently the health-related-quality of life (HRQOL) is diminished, associated with a higher morbidity and mortality. In the therapy of pain the WHO three-step analgesic ladder adapted for ESRD, was shown to be effective in dialysis patients. Of fundamental importance are various forms of non-pharmacological strategies including electrotherapy. Recently the so-called high tone external muscle stimulation (HTEMS) was very effective in the management of neuropathic pain in ESRD patients.

Impact of responder definition on the enriched enrollment randomized withdrawal trial design for establishing proof of concept in neuropathic pain.

The objective of this study was to evaluate how enrichment for responders increases assay sensitivity in an enriched enrollment randomized withdrawal (EERW) proof-of-concept (POC) study in neuropathic pain. Adults with moderate to severe peripheral neuropathic pain entered a 3- to 4-day screening period, followed by a 12-day titration to the highest tolerated dose that provided pain control (pregabalin 50-200mg t.i.d.), and then a 9-day maintenance period. Subjects were stratified as primary responders (⩾30%), secondary responders (⩾10% to <30%), or nonresponders (<10%) based on decrease in pain intensity and were randomized to placebo or pregabalin during the randomized withdrawal period. The primary endpoint was mean of average 24-h pain intensity during the last 3days of treatment period relative to the 3days before randomization. Time-to-efficacy-failure was the key secondary endpoint. Other features included not requiring discontinuation of current analgesic therapies and blinding investigators to study design elements that could contribute to non-treatment-related responses. Effect size (ES) (mean treatment difference/SD) was used to measure assay sensitivity. Pregabalin-treated subjects (n=52) had significantly less pain than those receiving placebo (n=51) (P⩽.003). Effect size of the primary endpoint was 0.72 for primary responders and decreased if secondary and nonresponders were included in the analysis. The highest ES (1.68) was demonstrated for the endpoint time-to-efficacy-failure seen in primary responders with painful diabetic neuropathy. The EERW trial design using time-to-efficacy-failure may provide a sensitive and efficient method to conduct POC studies of novel therapies in patients with neuropathic pain. Enriching a study population with patients who have achieved a 30% decrease in pain with an investigational therapy, and using time-to-efficacy-failure during the randomized withdrawal phase as the primary endpoint, can be used for a proof-of-concept study to optimize assay sensitivity and efficiently determine the analgesic potential of a new treatment for neuropathic pain.