Chronic Opioid Therapy and Central Sensitization in Sickle Cell Disease

Unmet Need: Mechanistic and Translational Studies of Sickle Cell Disease Pain as a Whole-Person Health Challenge

Sickle cell disease (SCD) is a lifelong monogenic, autosomal-recessive blood disease that predominantly affects individuals of African descent and those who self-identify as Black or Hispanic. Common SCD pathophysiological processes include adhesion, hemolysis, hypoxia, ischemia, oxidative stress, and vaso-occlusion, which often lead to substantial comorbidities and complications. Pain is one of the most common and significant clinical complications for individuals with SCD. Despite advancements in understanding the pathophysiology of SCD, the ways in which SCD pathophysiological processes contribute to nociception and pain signaling, processing, and perception remain largely unclear. Pain management for individuals with SCD is complex and presents unique challenges that must be considered depending on the presenting pain type (eg, acute pain episode vs chronic pain). Racism, stigma (including stigma associated with opioid use), and limited resources present additional challenges. Limited research has been conducted on major clinical features of SCD pain such as its ischemic, inflammatory, and neuropathic components; on its transition from acute to chronic form and across the lifespan; and on factors influencing SCD pain perception. Research on and management of SCD pain requires a whole-person approach, bringing together investigators from multiple disciplines such as hematologists, organ biologists, pain experts, physiologists, neuroscientists, psychologists, geneticists, microbiologists, immunologists, behavioral scientists, and clinicians. Multidisciplinary cross-training, with different platforms for information dissemination and communication, could help promote basic, mechanistic, and translational research to inform the optimization of current treatment strategies and the development of novel therapies for SCD pain. PERSPECTIVE: This review presents the research challenges and negative impact of SCD pain, a grossly understudied condition in a highly underserved population. It also highlights the barriers and opportunities in SCD pain research and could help clinicians better understand current treatment strategies from the whole-person perspective.

A Systemic Review of the Psychosocial Aspects of Chronic Pain in Youth With Sickle Cell Disease

OBJECTIVES

The psychosocial aspects of chronic pain among youth with sickle cell are poorly described and may be better understood within a biopsychosocial model of chronic pain as applied to youth living with sickle cell disease.

DESIGN

A systematic literature review was performed to synthesize the psychosocial factors contributing to chronic pain in this population. Criteria for study inclusion were primary quantitative research studies focused on psychosocial aspects of chronic pain among youth with sickle cell disease.

DATA SOURCES

PubMed, CINAHL, PsychINFO, and Scopus were searched for relevant articles.

REVIEW/ANALYSIS METHODS

Articles selected for full-text review were appraised for quality using the Joanna Briggs Institute Quality Appraisal Tools. Thirteen articles were included.

RESULTS

Depression, anxiety, pain catastrophizing, pain coping, executive functioning, and functional impairment were prevalent in youth living with sickle cell disease and chronic pain. Research gaps included the influence of stigma, injustice, peer interactions, and school and work on chronic pain.

CONCLUSIONS

The biopsychosocial model of chronic sickle cell disease-related pain for youth was developed and modified based on the results of this systematic review to remind clinicians of the various factors to consider in clinical practice and spur additional research in this field.

Incidence and risk factors of pain crisis after hematopoietic cell transplantation for sickle cell disease

ABSTRACT

Vaso-occlusive episodes (VOC) or pain crises are the most common indications for hematopoietic cell transplantation (HCT) for sickle cell disease (SCD). Elimination of pain crisis after HCT is an important patient-centered outcome and may improve understanding of the natural history of pain syndromes in SCD. We examined deidentified records of 763 patients followed-up for a median of 36.7 months (range, 0.3-168.6 months), with 69.6% patient's age <18 years at HCT, 83.3% patient's Karnofsky-Lansky performance score (KPS) ≥90, overall survival 92.9%, event-free survival 72.4%, graft failure (GF) 22.4%, AGVHD 21.4%, CGVHD 27%, and pain crisis 8.65%. On unadjusted logistic regression, increased risk of pain crisis after HCT was observed in patient's aged >10 years at HCT (range, 11-17 years; OR, 9.43; 95% CI, 3.20-27.79; P < .0001), in age ≥18 years (OR, 16.62; 95% CI, 5.85-47.16; P < .0001), in those with history of pain crisis 2 years before HCT (OR, 13.16; 95% CI, 4.08-42.42; P < .0001), alternate donors (haploidentical [OR, 4.80; 95% CI, 2.48-9.31; P < .0001], unrelated matched [OR, 2.71; 95% CI, 1.23-5.97; P = .0132], and mismatched unrelated [OR, 3.19; 95% CI, 1.44-7.05; P = .0041], and those with GF (n = 41 [5.37%]; OR, 7.15; 95% CI, 4.20-12.18; P < .0001). Pain crisis was less frequent with KPS of ≥90 (OR, 0.31; 95% CI, 0.18-0.55; P < .0001). Multivariable logistic regression models confirmed age at HCT, KPS, graft type, donor type, history of VOC 2 years before HCT, and GF as independent predictors of pain crisis after HCT and generated predictive models and nomograms for pain crisis after HCT for SCD, which can support shared decision making.

The Associations Between Opioid Use Disorder and Healthcare-Related Outcomes in Vaso-occlusive Crisis

BACKGROUND

In patients who experience frequent vaso-occlusive crises (VOC), opioid dependence may be due to a need for pain control as opposed to addiction; the implications of opioid use disorder (OUD) in this population are unclear.

OBJECTIVE

To compare outcomes in hospitalizations for VOC in those with a history of OUD to those without a history of OUD.

DESIGN

A retrospective assessment of hospitalizations for adults in the USA with a primary discharge diagnosis of VOC using the National Inpatient Sample database from 2016 to 2019. We also compared VOC hospitalizations to hospitalizations for all other reasons to assess differences in OUD-associated clinical factors.

PARTICIPANTS

In total, 273,460 hospitalizations for VOC; 23,120 (8.5%) of these hospital stays involved a secondary diagnosis of OUD.

MAIN MEASURES

Primary outcomes were length of hospital stay and cost. Mortality was a secondary outcome.

KEY RESULTS

Hospital length of stay was increased (mean 6.2 vs 4.9 days) in patients with OUD (adjusted rate ratio = 1.24, 95% CI 1.20-1.29, p < 0.001). Mean cost was also higher in those with OUD ($9076) than those without OUD ($8020, p < 0.001). Mortality was decreased in VOC hospitalizations in those with OUD, but the difference was not statistically significant (adjusted OR = 0.64, 95% CI 0.028-1.48, p = 0.30).

CONCLUSIONS

OUD is associated with increased length of stay and costs in patients with VOC. While there are many possible explanations, providers should consider undertreatment of pain due to addiction concerns as a potential factor; individualized pain plans to mitigate this challenge could be explored.

"Buprenorphine, It Works so Differently": Adults with Sickle Cell Disease Describe Transitioning to Buprenorphine for Treatment of Chronic Pain

A growing body of literature describes the use of buprenorphine for the treatment of chronic pain in people with sickle cell disease. The experiences of people with sickle cell disease who have tried buprenorphine have not yet reported. This qualitative descriptive study was conducted to explore perspectives on buprenorphine for chronic pain in sickle cell disease. We interviewed 13 participants with sickle cell disease who had been prescribed buprenorphine and had a clinic visit between December 1, 2020, and April 2022 in our Sickle Cell Center for Adults. Interviews were recorded, transcribed, and analyzed using thematic analysis. Eleven out of 13 participants were taking buprenorphine at the time of the interview, with a mean treatment duration of 33 months (SD 18, range 7-78 months). Five major themes were identified: 1) dissatisfaction with full agonist opioids; 2) navigating uncertainty with autonomy in deciding to try buprenorphine; 3) functional and relational changes after starting buprenorphine, 4) enduring systemic barriers to pain treatment, and 5) trusting treatment relationships are necessary when approaching patients about buprenorphine. The experience of adulthood living with sickle cell disease before and after starting buprenorphine is qualitatively different with significant improvements in social functioning. PERSPECTIVE: This study examined the experience of adults with sickle cell disease and chronic pain transitioning from full agonist opioids to buprenorphine. It is the first qualitative study of buprenorphine in people with sickle cell disease, contributing to a small but growing literature about buprenorphine and sickle cell disease.

Altered pain processing and sensitization in sickle cell disease: a scoping review of quantitative sensory testing findings

OBJECTIVES

Over 50% of adults living with sickle cell disease (SCD) have chronic pain, but the underlying mechanisms of chronic pain in this population remain unclear. Quantitative sensory testing is an important measurement tool for understanding pain and sensory processing. This scoping review summarizes quantitative sensory testing methodologies used in sickle cell studies and the evidence for central sensitization in this population.

METHODS

We conducted a systematic search of PubMed, Embase, and CINAHL to identify studies using quantitative sensory testing in individuals living with sickle cell disease. Search strategies were based on variations of the terms "sickle cell disease," and "quantitative sensory testing." Eligible studies were observational or experimental studies in human participants living with SCD that reported findings and detailed methodology for at least 1 quantitative sensory testing modality.

RESULTS

Our search yielded a total of 274 records; 27 of which are included in this scoping review. Of the 27 studies, 17 were original studies (with combined total of 516 adult and 298 pediatric participants), and 10 were secondary or subgroup analyses of these prior studies. Significant variation existed in quantitative sensory testing methodologies across studies, including testing locations, type and intensity of stimuli, and interpretation of findings. Of the identified studies, 22% (2/9 studies) reported sensory abnormalities in mechanical sensitivity and thresholds, 22% (2/9 studies) reported abnormal pressure pain thresholds, 46% (6/13 studies) reported sensory abnormalities in thermal pain thresholds and tolerance (cold and warm), and 50% (2/4 studies) reported abnormalities in temporal summation.

CONCLUSION

Future studies should use standardized quantitative sensory testing protocols with consistent and operationalized definitions of sensitization to provide clear insight about pain processing and central sensitization in sickle cell disease.

Rates of Opioid Misuse Amongst Patients Receiving Pain Management for Sickle Cell Disease in An Urban Setting

Background and Objective: Sickle Cell Disease (SCD) is known to cause acute severe pain episodes known as vaso-occlusive crisis (VOC) mainly treated with opioid analgesics. Since the opioid epidemic there is an interest in determining the opioid misuse potential in these patients. Therefore, the primary objective of this study is to determine the rates of opioid misuse among patients with SCD by assessing the rate of unexpected drug screening results in a sickle cell disease clinic. Methods: This was a retrospective chart review study conducted at the outpatient sickle cell disease clinic. The primary independent variables were the prescribed opioid medications while the primary dependent variable was the collected opioid metabolite. Descriptive statistics, linear regression and multivariate logistic regression analysis were conducted using SPSS version 24. Results: A total of 100 participants were recruited from July 1, 2018, to June 30, 2020 with 71 included in the analysis. The total mean of morphine milligram equivalents (MME) for all participants was 71.1±104.9 with 71% of participants having a daily calculated MME of <90MME. The odds of misusing an opioid were 6.72 times higher (P<.02) if a participant used marijuana compared to a participant who didn't. In addition, the odds of misusing an opioid were 2.47 times higher (P<.04) if the patient was prescribed an opioid daily dose greater than 90 MME as opposed to a daily dose less than 90 MME. Conclusion: Participants who consumed greater than 90 MME's per day and utilized marijuana were more likely to misuse opioids.

Differential clinical characteristics across traditional Chinese medicine (TCM) Syndromes in patients with sickle cell disease

Background

Pain is a common, debilitating, and poorly understood complication of sickle cell disease (SCD). The need for clinical pain management of SCD is largely unmet and relies on opioids as the main therapeutic option, which leads to a decreased quality of life (QoL). According to the literature, acupuncture has shown certain therapeutic effects for pain management in SCD. However, these clinical studies lack the guidance of Traditional Chinese Medicine (TCM) Syndrome Differentiation principles for treatment.

Aim

To characterize differences in clinical presentation amongst TCM diagnosed Syndromes in SCD patients.

Method

Fifty-two patients with SCD and 28 age- and sex-matched healthy controls (HCs) were enrolled in an ongoing trial of acupuncture. Each participant completed a series of questionnaires on pain, physical function, fatigue, sleep, anxiety, depression and QoL and underwent cold- and pressure-based quantitative sensory testing at baseline. Data on prescription opioid use over the 12 months prior to study enrollment was used to calculate mean daily morphine milligram equivalents (MME). Differences among the three TCM Syndromes were analyzed by one-way ANOVA followed by Tukey post hoc testing. Two-sample t-tests were used to compare SCD and HC groups.

Results

TCM diagnosis criteria classified SCD patients into one of three TCM Syndromes: (a) Equal; (b) Deficiency; and (c) Stagnation. The Stagnation group exhibited higher pain interference, physical dysfunction, nociplastic pain, fatigue, anxiety, depression, MME consumption and lower sleep quality and QoL compared to the Equal group. Few differences were observed between HCs and the Equal SCD group across outcomes. Deficiency and Stagnation groups were differentiated with observed- and patient-reported clinical manifestations.

Conclusion

These findings suggest that TCM diagnosed Syndromes in SCD can be differentially characterized using validated objective and patient-reported outcomes. Because characteristics of pain and co-morbidities in each SCD patient are unique, targeting specific TCM "Syndromes" may facilitate treatment effectiveness with a Syndrome-based personalized treatment plan that conforms to TCM principles. These findings lay the foundation for the development of tailored acupuncture interventions based on TCM Syndromes for managing pain in SCD. Larger samples are required to further refine and validate TCM diagnostic criteria for SCD.

Adolescents and Young Adults With Sickle Cell Disease: Nociplastic Pain and Pain Catastrophizing as Predictors of Pain Interference and Opioid Consumption

OBJECTIVES

Some patients with sickle cell disease (SCD) have features of nociplastic pain. While research suggests that many patients with nociplastic pain consume more opioids due to opioid nonresponsiveness, little is known about the impact of nociplastic pain and pain catastrophizing on opioid consumption and pain interference among adolescents and young adults (AYA) with SCD. The purpose of this study was to (1) characterize nociplastic pain and pain catastrophizing among AYA with SCD, and (2) determine whether these characterizations are associated with subsequent opioid consumption and pain interference 1 month after characterization.

METHODS

Participants completed surveys characterizing nociplastic pain and catastrophizing at a routine clinic visit (baseline). Thereafter, participants received weekly text messages that included pain interference and opioid consumption surveys. Multipredictor 2-part models were used to evaluate the predictive relationships between baseline characterizations and subsequent pain interference, and opioid consumption.

RESULTS

Forty-eight AYA aged 14 to 35 completed baseline measures. Twenty-five percent of participants had scores suggestive of nociplastic pain. Greater nociplastic pain features significantly increased the odds of consuming opioids (odds ratio=1.2) and having greater interference from pain (odds ratio=1.46). Regression analyses found that greater baseline nociplastic pain characteristics were significantly associated with opioid consumption (β=0.13) and pain interference (β=0.061); whereas higher pain catastrophizing scores predicted less opioid consumption (β=-0.03) and less pain interference (β=-0.0007).

DISCUSSION

In this sample of AYA with SCD, features of nociplastic pain predicted higher subsequent opioid consumption and pain interference. Being aware of nociplastic pain features in patients with SCD may better guide individualized pain management.

The Complex Association of Daily Opioid Dose with Visits for Pain in Sickle Cell Disease: Tolerance or Treatment-Refractory Pain?

INTRODUCTION

Opioids are used for acute and chronic pain in patients with sickle cell disease. How outpatient opioid regimens relate to acute care visits is of interest given the risks of high opioid doses and high hospital utilization. A prior study by our group suggested that outpatient opioid treatment for chronic pain could contribute to a vicious cycle of treatment-refractory acute pain, greater acute care utilization, and escalating opioid doses. The present larger naturalistic observational study was undertaken to determine whether the results were reliable across multiple acute care settings.

METHODS

One year of clinical data on patients (n = 291) followed in the Sickle Cell Center for Adults (August 2018 to July 2019) were extracted, including visits to the emergency department, visits to the infusion center, and inpatient admissions. Outpatient opioid dosage was used to predict acute care treatment in generalized linear models that were controlled for patient, disease, and treatment characteristics.

RESULTS

Outpatient opioid dosage predicted dosage during visits but did not predict visit length or pain relief. Higher outpatient opioid dosage was associated with greater number of visits. However, in post hoc analyses, this relationship was nonlinear, with a clear positive association only for those prescribed the lowest 50% of dosages.

DISCUSSION

Higher outpatient opioid dosage predicted higher dosages during acute care visits to achieve the same pain score improvement, which is more consistent with opioid tolerance than with treatment-refractory pain. The relationship of outpatient opioid dosage with number of acute care visits was more complex, which suggests that opioid consumption at lower levels is driven by intermittent acute pain and opioid consumption at higher levels is driven by chronic pain.

Depressive and Insomnia Symptoms Sequentially Mediate the Association Between Racism-Based Discrimination in Healthcare Settings and Clinical Pain Among Adults With Sickle Cell Disease

Racism-based discrimination in healthcare settings has been associated with clinical pain in adults living with sickle cell disease; however, no studies have examined depressive and insomnia symptoms as mechanisms that may drive this relationship. This secondary data analysis examined associations between depressive and insomnia symptoms, racism-based discrimination, and clinical pain. Seventy-one adults with sickle cell disease (70% female, Mage = 38.79) provided baseline reports of racism-based discrimination, depressive symptoms, insomnia symptoms, and pain (severity, interference, catastrophizing), and they completed daily diaries of pain severity and interference over 3 months. In a sequential mediation model, baseline depressive (1st) and insomnia symptoms (2nd) significantly mediated the association between racism-based discrimination and baseline pain interference, average daily diary pain severity, and average daily diary pain interference. Although the mediation model with baseline pain severity as the outcome was significant, the total and direct effects were not. Results indicate that discrimination in healthcare settings contributes to depression, which may act on pain through sleep disturbance. Findings support the need for systemic and structural changes to eliminate discrimination in healthcare settings and behavioral mood and sleep interventions to reduce the impact of discrimination on clinical pain. PERSPECTIVE: The relationship between discrimination in healthcare settings and pain in adults with sickle cell disease may be driven by depression and sleep disturbance, modifiable risk factors and potential treatment targets. Results suggest that systemic, structural, and institutional changes must be implemented to promote better patient care and health outcomes.

Management of Older Adults with Sickle Cell Disease: Considerations for Current and Emerging Therapies

People with sickle cell disease (SCD) are living longer than ever before, with the median survival increasing from age 14 years in 1973, beyond age 40 years in the 1990s, and as high as 61 years in recent cohorts from academic centers. Improvements in survival have been attributed to initiatives, such as newborn screening, penicillin prophylaxis, vaccination against encapsulated organisms, better detection and treatment of splenic sequestration, and improved transfusion support. There are an estimated 100,000 people living with SCD in the United States and millions of people with SCD globally. Given that the number of older adults with SCD will likely continue to increase as survival improves, better evidence on how to manage this population is needed. When managing older adults with SCD (defined herein as age ≥ 40 years), healthcare providers should consider the potential pitfalls of extrapolating evidence from existing studies on current and emerging therapies that have typically been conducted with participants at mean ages far below 40 years. Older adults with SCD have historically had little to no representation in clinical trials; therefore, more guidance is needed on how to use current and emerging therapies in this population. This article summarizes the available evidence for managing older adults with SCD and discusses potential challenges to using approved and emerging drugs in this population.

Inhibition of DAGLβ as a therapeutic target for pain in sickle cell disease

Sickle cell disease (SCD) is the most common inherited disease. Pain is a key morbidity of SCD and opioids are the main treatment but their side effects emphasize the need for new analgesic approaches. Humanized transgenic mouse models have been instructive in understanding the pathobiology of SCD and mechanisms of pain. Homozygous (HbSS) Berkley mice express >99% human sickle hemoglobin and several features of clinical SCD including hyperalgesia. Previously, we reported that the endocannabinoid 2-arachidonoylglycerol (2-AG) is a precursor of the pro-nociceptive mediator prostaglandin E2-glyceryl ester (PGE2-G) which contributes to hyperalgesia in SCD. We now demonstrate the causal role of 2-AG in hyperalgesia in sickle mice. Hyperalgesia in HbSS mice correlated with elevated levels of 2-AG in plasma, its synthesizing enzyme diacylglycerol lipase β (DAGLβ) in blood cells, and with elevated levels of PGE2 and PGE2-G, pronociceptive derivatives of 2-AG. A single intravenous injection of 2-AG produced hyperalgesia in non-hyperalgesic HbSS mice, but not in control (HbAA) mice expressing normal human HbA. JZL184, an inhibitor of 2-AG hydrolysis, also produced hyperalgesia in non-hyperalgesic HbSS or hemizygous (HbAS) mice, but did not influence hyperalgesia in hyperalgesic HbSS mice. Systemic and intraplantar administration of KT109, an inhibitor of DAGLβ, decreased mechanical and heat hyperalgesia in HbSS mice. The decrease in hyperalgesia was accompanied by reductions in 2-AG, PGE2 and PGE2-G in the blood. These results indicate that maintaining the physiological level of 2-AG in the blood by targeting DAGLβ may be a novel and effective approach to treat pain in SCD.

The management of chronic pain in sickle cell disease: an interview with Nadine Matthie

Nadine Matthie, PhD, RN, CNL is an Assistant Professor in the Nell Hodgson Woodruff School of Nursing at Emory University in Atlanta, GA, USA. As a nurse scientist, she has conducted behavioral research to investigate pain and self-management in adults living with sickle cell disease, and address chronic, non vaso-occlusive pain in this population. Dr Matthie is developing non pharmacological, patient-centered, self-management strategies that incorporate virtual reality and biopsychosocial approaches to help manage chronic pain and reduce the burden of sickle cell; thereby, facilitating new, personalized approaches to management of chronic pain conditions in the home setting. Her research has been published in several national and international peer-reviewed sources for various disciplines, including nursing, medicine, music therapy and psychology.

Converting adults with sickle cell disease from full agonist opioids to buprenorphine: A reliable method with safety and early evidence of reduced acute care utilization

Buprenorphine, a novel opioid with complex pharmacology, is effective for treating pain and is qualitatively safer than high-dose full agonist opioid therapy; but transitioning to buprenorphine can be technically complex and carries some risk of precipitated withdrawal. We report our clinic's experience converting 36 patients with sickle cell disease (SCD) from full agonist opioids to buprenorphine using a method developed in the past 10 years. Thirty of these patients were induced using a standard outpatient protocol and six were induced during medical admissions. Typically, patients were on high-dose chronic opioid therapy (COT) with inadequate response, and often with very high acute care utilization. Unlike prior case series, the method of induction, dosing, and management of withdrawal are detailed, as are post-induction adverse events. There were seven adverse events in the first 3 days following standard induction, and two of which were judged to be definitely related to the induction but none with any lasting sequelae. At 6 months follow-up, five participants had discontinued buprenorphine (16.67%), and overall acute care visits dropped from a mean of 10.50 (SD 11.35) in the 6 months pre-induction to 2.89 (SD 3.40) in the 6 months post-induction. In an appropriately interdisciplinary care setting, buprenorphine shows promise as a safe alternative to COT with early evidence of benefit for high-utilizing patients with SCD.

A Standardized Emergency Department Order Set Decreases Admission Rates and In-Patient Length of Stay for Adults Patients with Sickle Cell Disease

INTRODUCTION

Pain associated with sickle cell disease (SCD) causes severe complications and frequent presentation to the emergency department (ED). Patients with SCD frequently report inadequate pain treatment in the ED, resulting in hospital admission. A retrospective analysis was conducted to assess a quality improvement project to standardize ED care for patients presenting with pain associated with SCD.

METHODS

A 3-year prospective quality improvement initiative was performed. Our multidisciplinary team of providers implemented an ED order set in 2019 to improve care and provide adequate analgesia management. Our primary outcome was the overall hospital admission rate for patients after the intervention. Secondary outcome measures included ED disposition, rate of return to the ED within 72 hours, ED pain scores at admission and discharge, ED treatment time, in-patient length of stay, non-opioid medication use, and opioid medication use.

RESULTS

There was an overall 67% reduction in the hospital admission rate after implementation of the order set (P = 0.005) and a significant decrease in the percentage admission rate month over month (P = 0.047). Time to the first non-opioid analgesic decreased by 71 minutes (P > 0.001), and there was no change in time to the first opioid medication. The rate of return to the ED within 72 hours remained unchanged (7.0% vs 7.1%) (P = 0.93), and the ED elopement rate remained unchanged (1.3% vs 1.85%) (P = 0.93). After the implementation, there were significant increases in the prescribing of orally administered acetaminophen (7%), celecoxib (1.2%), and tizanidine (12.5%) and intravenous ketamine (30.5%) and ketorolac (27%). ED pain scores at discharge were unchanged for both hospital-admitted (7.12 vs 7.08) (P = 0.93) and non-admitted (5.51 vs 6.11) (P = 0.27) patients. The resulting potential cost reduction was determined to be $193,440 during the 12-month observation period, with the mean cost per visit decreasing by $792.

CONCLUSIONS

Use of a standardized and multimodal ED order set reduced hospital admission rates and the timeliness of analgesia without negatively impacting patients' pain.

Nociceptors protect sickle cell disease mice from vaso-occlusive episodes and chronic organ damage

Sickle cell disease (SCD) is a common hereditary hematologic disorder. SCD patients suffer from acute vaso-occlusive episodes (VOEs), chronic organ damage, and premature death, with few therapeutic options. Although severe pain is a major clinical manifestation of SCD, it remains unknown whether nociception plays a role in SCD pathogenesis. To address this question, we generated nociceptor-deficient SCD mice and found, unexpectedly, that the absence of nociception led to more severe and more lethal VOE, indicating that somatosensory nerves protect SCD mice from VOE. Mechanistically, the beneficial effects of sensory nerves were induced by the neuropeptide calcitonin gene–related peptide (CGRP), which acted on hematopoietic cells. Additionally, oral capsaicin consumption, which can activate somatosensory nerves by binding to TRPV1, dramatically alleviated acute VOE and significantly prevented chronic liver and kidney damage in SCD mice. Thus, the manipulation of nociception may provide a promising approach to treat SCD.

Implementation of Individualized Pain Care Plans Decreases Length of Stay and Hospital Admission Rates for High Utilizing Adults with Sickle Cell Disease

OBJECTIVE

Patients with sickle cell disease (SCD) face inconsistent effective analgesic management, leading to high inpatient healthcare utilization and significant financial burden for healthcare institutions. Current evidence does not provide guidance for inpatient management of acute pain in adults with sickle cell disease. We conducted a retrospective analysis of a longitudinal cohort quality improvement project to characterize the role of individualized care plans on improving patient care and reducing financial burden in high healthcare-utilizing patients with SCD-related pain.

METHODS

Individualized care plans were developed for patients with hospital admissions resulting from pain associated with sickle cell disease. A 2-year prospective longitudinal cohort quality improvement project was performed and retrospectively analyzed. Primary outcome measure was duration of hospitalization. Secondary outcome measures included: pain intensity; 7, 30, and 90-day readmission rates; cost per day; total admissions; total cost per year; analgesic regimen at index admission; and discharge disposition.

RESULTS

Duration of hospitalization, the primary outcome, significantly decreased by 1.23 days with no worsening of pain intensity scores. Seven-day readmission decreased by 34%. Use of intravenous hydromorphone significantly decreased by 25%. The potential cost saving was $1,398,827 as a result of this quality initiative.

CONCLUSIONS

Implementation of individualized care plans reduced both admission rate and financial burden of high utilizing patients. Importantly, pain outcomes were not diminished. Results suggest that individualized care plans are a promising strategy for managing acute pain crisis in adult sickle cell patients from both care-focused and utilization outcomes.

Pain in sickle cell disease: current and potential translational therapies

Pain is a major comorbidity of sickle cell disease (SCD). Patients with SCD may suffer from both acute and chronic pain. Acute pain is caused by recurrent and unpredictable episodes of vaso-occlusive crises (VOC), whereas the exact etiology of chronic pain is still unknown. Opioids are the mainstay for pain treatment, but the opioid epidemic has significantly altered access to prescription opioids and has brought concerns over their long-term use into the forefront, which have negatively impacted the treatment of sickle pain. Opioids remain potent analgesics but growing opioid-phobia has led to the realization of an unmet need to develop nonopioid therapies that can provide relief for severe sickle pain. This realization has contributed to the approval of 3 different drugs by the Food and Drug Administration (FDA) for the treatment of SCD, particularly to reduce VOC and/or have an impact on the pathobiology of SCD. In this review, we outline the challenges and need for validation of side-effects of opioids and provide an update on the development of mechanism-based translational therapies, specifically targeting pain in SCD.

Sickle Cell Disease and Pain: Is it all Vaso-occlusive Crises?

OBJECTIVES

Acute pain is the main complication of sickle cell disease. Chronic pain (CP) and neuropathic pain (NP) may also be experienced, but have not been formally described in Jamaican patients. A cross-sectional study was conducted to determine their prevalence and characteristics, and to determine the common pain locations and modalities of management.

MATERIALS AND METHODS

All well individuals with sickle cell disease patients 14 years and older, not pregnant and without a history of clinical stroke were consecutively recruited. Anthropometric measurements, hematology studies, an analgesia checklist, and the Adult Sickle Cell Quality of Life Measurement Information System questionnaire were completed. The painDETECT questionnaire was completed to describe NP and pain patterns-from which CP was defined.

RESULTS

There were 257 patients in total, with 55.6% being females; the mean age of the patients was 31.7±12 years, and 75% had the SS genotype. Almost all patients (92.6%) had had an acute pain crisis in their lifetime and 72.4% in the last year. The mean severity at last attack was 6.8±3.1 on a scale of 0 to 10. The prevalences of CP and NP were 21.5% and 17.9%, respectively. Female sex, the presence of current leg ulcers, and the use of a strong opioid in the last 4 weeks produced higher odds of NP, whereas older age, milder genotypes, and daily analgesic use had the highest odds of CP. Opioids were used by 40.1% of the patients in the previous 4 weeks, whereas nonpharmacological treatments such as physiotherapy was less used, but reported to be very effective.

DISCUSSION

CP and NP should be assessed during routine care of sickle cell pain so that targeted therapies can be applied.

Comparing the Effectiveness of Education Versus Digital Cognitive Behavioral Therapy for Adults With Sickle Cell Disease: Protocol for the Cognitive Behavioral Therapy and Real-time Pain Management Intervention for Sickle Cell via Mobile Applications (CaRISMA) Study

Background

Patients with sickle cell disease (SCD) experience significant medical and psychological stressors that affect their mental health, well-being, and disease outcomes. Digital cognitive behavioral therapy (CBT) has been used in other patient populations and has demonstrated clinical benefits. Although evidence-based, nonpharmacological interventions for pain management are widely used in other populations, these treatments have not been well studied in SCD. Currently, there are no adequately powered large-scale clinical trials to evaluate the effectiveness and dissemination potential of behavioral pain management for adults with SCD. Furthermore, some important details regarding behavioral therapies in SCD remain unclear—in particular, what works best for whom and when.

Objective

Our primary goal is to compare the effectiveness of two smartphone–delivered programs for reducing SCD pain symptoms: digital CBT versus pain and SCD education (Education). Our secondary goal is to assess whether baseline depression symptoms moderate the effect of interventions on pain outcomes. We hypothesize that digital CBT will confer greater benefits on pain outcomes and depressive symptoms at 6 months and a greater reduction in health care use (eg, opioid prescriptions or refills or acute care visits) over 12 months.

Methods

The CaRISMA (Cognitive Behavioral Therapy and Real-time Pain Management Intervention for Sickle Cell via Mobile Applications) study is a multisite comparative effectiveness trial funded by the Patient-Centered Outcomes Research Institute. CaRISMA is conducted at six clinical academic sites, in partnership with four community-based organizations. CaRISMA will evaluate the effectiveness of two 12-week health coach–supported digital health programs with a total of 350 participants in two groups: CBT (n=175) and Education (n=175). Participants will complete a series of questionnaires at baseline and at 3, 6, and 12 months. The primary outcome will be the change in pain interference between the study arms. We will also evaluate changes in pain intensity, depressive symptoms, other patient-reported outcomes, and health care use as secondary outcomes. We have 80% power to detect a difference of 0.37 SDs between study arms on 6-month changes in the outcomes with 15% expected attrition at 6 months. An exploratory analysis will examine whether baseline depression symptoms moderate the effect of the intervention on pain interference.

Results

This study will be conducted from March 2021 through February 2022, with results expected to be available in February 2023.

Conclusions

Patients with SCD experience significant disease burden, psychosocial stress, and impairment of their quality of life. CaRISMA proposes to leverage digital technology and overcome barriers to the routine use of behavioral treatments for pain and depressive symptoms in the treatment of adults with SCD. The study will provide data on the comparative effectiveness of digital CBT and Education approaches and evaluate the potential for implementing evidence-based behavioral interventions to manage SCD pain.

Trial Registration

ClinicalTrials.gov NCT04419168; https://clinicaltrials.gov/ct2/show/NCT04419168.

International Registered Report Identifier (IRRID)

PRR1-10.2196/29014

A pilot study of the acceptability, feasibility and safety of yoga for chronic pain in sickle cell disease

OBJECTIVES

To determine the acceptability, feasibility and safety of yoga for chronic pain in sickle cell disease.

DESIGN AND SETTING

In Part A of this two-part study, adolescents with SCD and chronic pain (Group 1) and their parent (Group 2) completed a survey designed to capture pain characteristics, attitudes and practices related to yoga, and potential acceptability of a yoga program. In Part B, the study assessed the feasibility and safety of an instructor-led group yoga program. The study was registered on clinicaltrials.gov (NCT03694548).

INTERVENTION

Eight instructor-led group yoga sessions.

MAIN OUTCOME MEASURES

Feasibility and safety outcomes were chosen a priori, as follows: 1) Proportion of adolescent patients with SCD and chronic pain approached that consent to participate in Part A, 2) Proportion of adolescent participants enrolled in Part A that consent to participate in Part B, 3) Proportion of participants enrolled in Part B that attend at least 6 of 8 yoga sessions, 4) Proportion of participants enrolled in Part B with an ED visit or a hospitalization for pain within 24 h of completion of each yoga session, 5) Proportion of participants in Part B who complete all study assessments before, and at the end of the yoga program, 6) Adherence to submission of pain diary.

RESULTS

The median age of 15 patient participants in Part A was 16 (IQR 14-17), and 14 parents was 43.5 (IQR 42-51). Most participants were female. Most participant responses indicated a positive opinion of yoga. Nine adolescents (60 %) from Part A participated in Part B of the study. The median age of 9 participants in Part B was 17 (IQR 15-18), and 5 of the 9 participants were female (53.3 %). Only one participant was able to attend 3 of the 8 yoga sessions offered, and did not experience any ED visits or hospitalizations following the yoga sessions. None of the other feasibility endpoints were met in this study.

CONCLUSIONS

Patients with SCD and chronic pain overall have a positive opinion of yoga, but there are challenges with recruitment and retention of participants in a clinical trial of yoga, and barriers to feasibility of an in-person group yoga intervention.

Diet and companionship modulate pain via a serotonergic mechanism

Treatment of severe chronic and acute pain in sickle cell disease (SCD) remains challenging due to the interdependence of pain and psychosocial modulation. We examined whether modulation of the descending pain pathway through an enriched diet and companionship could alleviate pain in transgenic sickle mice. Mechanical and thermal hyperalgesia were reduced significantly with enriched diet and/or companionship. Upon withdrawal of both conditions, analgesic effects observed prior to withdrawal were diminished. Serotonin (5-hydroxytryptamine, 5-HT) was found to be increased in the spinal cords of mice provided both treatments. Additionally, 5-HT production improved at the rostral ventromedial medulla and 5-HT accumulated at the dorsal horn of the spinal cord of sickle mice, suggesting the involvement of the descending pain pathway in the analgesic response. Modulation of 5-HT and its effect on hyperalgesia was also investigated through pharmaceutical approaches. Duloxetine, a serotonin-norepinephrine reuptake inhibitor, showed a similar anti-nociceptive effect as the combination of diet and companionship. Depletion of 5-HT through p-chlorophenylalanine attenuated the anti-hyperalgesic effect of enriched diet and companionship. More significantly, improved diet and companionship enhanced the efficacy of a sub-optimal dose of morphine for analgesia in sickle mice. These findings offer the potential to reduce opioid use without pharmacological interventions to develop effective pain management strategies.

Sickle Cell Disease

Sickle cell disease is an umbrella term for a group of hemoglobinopathies characterized by the presence of 2 β-globin gene mutations or deletions, at least 1 of which is the point mutation that leads to the production of hemoglobin S. Sickle cell disease is associated with hemolytic anemia, significant chronic end-organ damage, and early death. In high-income countries, at least 95% of children with the disease survive into adulthood, resulting in a growing population of affected adults with significant comorbidities, complex medical issues, and not enough specialists to provide care. Hydroxyurea is the primary therapy, and recent advances in understanding disease pathophysiology have led to new therapies; progress in bone marrow transplant and gene editing has resulted in cure in some patients. The purpose of this review is to provide an overview of the diagnosis, common acute and chronic clinical manifestations, and best practices for management of sickle cell disease.

Optimizing the management of chronic pain in sickle cell disease

Chronic pain in sickle cell disease (SCD) refers to pain present on most days lasting over six months. It can start during childhood and the prevalence increases with age. By adulthood, over 55% of patients experience pain on over 50% of days; 29% reporting pain on 95% of days. The true prevalence of chronic pain in SCD is likely underappreciated as it is mostly managed at home. Patients with chronic pain and SCD frequently seek acute care for exacerbation of underlying chronic pain difficult to distinguish from their usual acute vaso-occlusive crises. When treating chronic pain in SCD, the challenge is distinguishing between non-SCD related etiologies versus chronic pain resulting from SCD pathophysiological processes. This distinction is important to delineate as it will drive appropriate management strategies. Chronic pain in SCD has profound consequences for the patient; is often associated with comorbid psychiatric illnesses (depression and anxiety), not dissimilar from other chronic pain syndromes. They may also experience challenges with sleep hygiene, various somatic symptoms, and chronic fatigue that impair quality of life. How best to treat chronic pain in SCD is not definitively established. Both acute and chronic pain in SCD is typically treated with opioids. Emerging data suggests that chronic opioid therapy (COT) is a suboptimal treatment strategy for chronic pain. This review will discuss the complexity of managing chronic pain in SCD; pain that may be dependent or independent of the underlying SCD diagnosis. We will also describe alternative treatment approaches to high-dose COT.

Neuropathic pain in sickle cell disease: measurement and management

The identification of chronic pain and neuropathic pain as common contributors to the overall pain experience of patients with sickle cell disease (SCD) has altered the way we should evaluate difficult-to-treat pain. The recognition of these 2 entities is not generally routine among various medical specialties and provider levels that treat SCD. Due to the relative recency with which neuropathic pain was first described in SCD, validated assessment tools and evidence-based treatments remain lacking. Although clinical assessment and judgment must continue to inform all decision making in this understudied area of SCD pain management, a number of validated neuropathic pain assessment tools exist that can make possible a standardized evaluation process. Similarly, investigation of available neuropathic pain treatments for the uniquely complex pain phenotypes of SCD has only just begun and is better established in pain conditions other than SCD. The aim of this review is to briefly summarize the proposed basic pathophysiology, assessment, and treatment of neuropathic pain in patients with SCD. Furthermore, the aim of this review is to encourage an expanded framework for the assessment and treatment of SCD pain that appreciates the hidden complexities of this common complication of SCD.

Pain Experience, Physical Function, Pain Coping, and Catastrophizing in Children With Sickle Cell Disease Who Had Normal and Abnormal Sensory Patterns

CONTEXT

Sickle cell disease (SCD) is associated with recurrent pain that could lead to abnormal sensory patterns (ASPs).

OBJECTIVES

The purpose of this study is to compare children with SCD who had normal sensory patterns (NSPs) and ASPs in pain experience, physical function, pain coping, and pain catastrophizing.

METHODS

Children with quantitative sensory testing data were selected from a larger study that examined pain and symptoms in children with SCD. Comparisons were made between children with NSP (n = 35; 13.9 ± 1.9 years) and ASP (n = 13; 12.8 ± 1.9 years). Children completed the Adolescent Pediatric Pain Tool, Functional Disability Inventory, Pain Coping Questionnaire, and Pain Catastrophizing Scale.

RESULTS

No significant differences were found in pain intensity (2.9 ± 3.0 vs. 2.6 ± 2.8 on 0-10 Visual Analogue Scale) between the NSP and ASP, respectively. The most common marked pain sites for both groups were lower extremities (22.9%), head and neck (20.8%), and upper extremities (20.8%). Functional Disability Inventory scores were significantly worse in ASP (38.5%) compared with NSP (11.4%). The ASP group had significantly worse scores in emotion-focused pain coping subscales.

CONCLUSION

Children with SCD with ASP had worse functional disability, were expressing more affective pain quality, and had emotion-focused pain coping compared with NSP. Future studies are needed to examine the effectiveness of physical activities on the physical function as well as psychosocial interventions such as peer support and creative arts expression to minimize development of ASP in children with SCD.

Opioid-Induced Sickle Cell Crisis With Multiple, Life-threatening Complications

The risk of opioid use disorder among patients with sickle cell disease who are treated with chronic opioids remains unclear, but the complications associated with opioid use and overdose can be accentuated in those with sickle cell disease. In this case report, we describe a 13-year-old girl with sickle cell disease who presented to the emergency department after a morphine overdose causing renal infarction, acute kidney injury, acute respiratory distress syndrome, and posterior reversible encephalopathy syndrome.

Medical marijuana certification for patients with sickle cell disease: a report of a single center experience

More than one-third of adults with sickle cell disease (SCD) report using cannabis-based products. Many states list SCD or pain as qualifying conditions for medical marijuana, but there are few data to guide practitioners whether or whom should be certified. We postulated that certifying SCD patients may lead to a reduction in opioid use and/or health care utilization. Furthermore, we sought to identify clinical characteristics of patients who would request this intervention. Retrospective data obtained over the study period included rates of health care and opioid utilization for 6 months before certification and after certification. Patients who were certified but failed to obtain medical marijuana were compared with those who obtained it. Patients who were certified were invited to participate in a survey regarding their reasons for and thoughts on certification. Patients who were certified for medical marijuana were compared with 25 random patients who did not request certification. Fifty adults with SCD were certified for medical marijuana and 29 obtained it. Patients who obtained medical marijuana experienced a decrease in admission rates compared with those who did not and increased use of edible cannabis products. Neither group had changes in opioid use. Patients who were certified for medical marijuana had higher rates of baseline opioid use and illicit cannabis use compared with those who did not request certification. Most patients with SCD who requested medical marijuana were already using cannabis illicitly. Obtaining medical marijuana decreased inpatient hospitalizations.

The Relationship between Cognitive and Emotional Factors and Healthcare and Medication Use in People Experiencing Pain: A Systematic Review

Pain conditions are among the leading causes of global disability, impacting on global healthcare utilization (HCU). Health seeking behavior might be influenced by cognitive and emotional factors (CEF), which can be tackled by specific therapies. The purpose of this study was to systematically review the evidence concerning associations between CEF and HCU in people experiencing pain. Three databases were consulted: PubMed, Web of Science and EconLit. Risk of bias was assessed using the Downs and Black Checklist (modified). A total of 90 publications (total sample n = 59,719) was included after double-blind screening. In people experiencing pain, positive associations between general anxiety symptoms, depressive symptoms and catastrophizing and pain medication use were found. Additionally, there appears to be a relationship between general anxiety and depressive symptoms and opioid use. Symptom-related anxiety and psychological distress were found to be positively related with consulting behavior. Last, a positive association between use of complementary and alternative medicine and level of perceived symptom control was confirmed in people with pain. For other relationships no evidence or inconsistent findings were found, or they were insufficiently studied to draw firm conclusions, indicating that more research on this topic is needed.

Do chronic pain and comorbidities affect brain function in sickle cell patients? A systematic review of neuroimaging and treatment approaches

Sickle cell disease (SCD) is a medical condition in which chronic pain is common and negatively impacts psychosocial function and quality of life. Although the brain mechanisms underlying chronic pain are well studied in other painful conditions, the brain mechanisms underlying chronic pain and the associated psychosocial comorbidities are not well established in SCD. A growing literature demonstrates the effect of treatment of chronic pain, including pharmacological and nonpharmacological treatments, on brain function. The present systematic review aimed to (1) determine the effects of chronic pain and psychosocial comorbidities on brain function of patients with SCD; (2) summarize pharmacological and nonpharmacological approaches to treat these symptoms; and (3) identify areas for further investigation of potential beneficial effects of treatments on brain function. Titles were screened using predefined criteria, including SCD, and abstracts and full texts were reviewed by 2 independent reviewers. A total of 1167 SCD articles were identified, and 86 full articles were included covering 3 sections: chronic pain (4 studies), psychosocial comorbidities (11 studies), and pharmacological and nonpharmacological treatments (71 studies). Neuroimaging evidence demonstrates aberrant neural processing related to chronic pain and psychosocial comorbidities in SCD beyond ischemic stroke and cerebral hemorrhage. Although neuroimaging studies show an important role for psychological factors, pain management is nearly exclusively based on opioids. Behavior therapy seems useful to improve psychological symptoms as well as chronic pain and quality of life. Further investigation is required with larger cohorts, matched controls, and examination of treatment-related neural mechanisms.

Characteristics and potential biomarkers of adult sickle cell patients with chronic pain

OBJECTIVES

In this study, we investigated the evolution of chronic pain in sickle cell patients (SCD) as an age-dependent phenomenon and studied the frequency of vaso-occlusive episode frequency, opioid use, quantitative sensory testing (QST), and biomarkers of chronic pain (CP).

METHODS

We undertook a cross-sectional study of the evolution of CP in SCD. A total of 72 subjects (age 15-66) were enrolled. VOE frequency, presence of CP hydroxyurea (HU) therapy, opioid use, and laboratory parameters were collected. QST was performed, and plasma tryptase, substance P, and NGF (Nerve Growth Factor) levels were assayed.

RESULTS

There was an age-dependent increase in frequency of CP, VOEs, opioid use, and Von Frey monofilament values. CP patients had significantly higher opioid use (daily morphine equivalents) (52.8 mg vs 6.94 mg, P = .009), suggesting a correlation between opioid use and hyperalgesia. NGF levels were also significantly higher (P = .051). Our results confirm previous observations of an age-dependent increase in the proportion of patients with CP and support the contributing role of mast cell activation and neurogenic inflammation.

CONCLUSIONS

This is the first study of NGF as a possible biomarker of CP in SCD. If confirmed, this could provide a diagnostic marker and therapeutic target for CP in SCD.

A Healthcare Improvement Initiative to Increase Multidisciplinary Pain Management Referrals for Youth with Sickle Cell Disease

BACKGROUND

Chronic pain is a complex integration of biological, psychological, and social variables. Multidisciplinary pain management experts design interventions that treat the multidimensional experience. Children and adolescents with sickle cell disease (SCD) are at risk for chronic pain. Increased risk is associated with multiple characteristics including sickle cell genotype, age, gender, frequency of hospitalization, duration of hospitalization, and certain comorbid diagnoses. Referral to pain management professionals for this population is often delayed.

AIMS

To increase multidisciplinary pain management referrals for youth with SCD identified to be at risk for chronic pain.

DESIGN

Implementation research.

SETTING

One pediatric, academic medical facility serving as a regional sickle cell treatment center in the Midwest.

PARTICIPANTS

Children greater than 2 years of age and less than 21 years of age with laboratory confirmed SCD.

METHODS

Implementation of an evidence-based screening tool using the consolidated framework for implementation research (CFIR) to guide project planning, design, and evaluation. The CFIR model was paired with the Plan-Do-Study-Act (PDSA) quality improvement methodology to operationalize workflow and sustain project aims.

RESULTS AND CONCLUSIONS

Eighty-four percent of all eligible patients were screened during their routine sickle cell appointments resulting in a 110% increase in multidisciplinary pain management referrals. Future interventions and PDSA cycles are targeted at improving attendance at scheduled appointments, reducing hospitalizations, decreasing 30-day readmissions, and shortening length of stay.

Mechanisms of pain in sickle cell disease

Objectives

The hallmark of sickle cell disease (SCD) is acute and chronic pain, and the pain dominates the clinical characteristics of SCD patients. Although pharmacological treatments of SCD targeting the disease mechanisms have been improved, many SCD patients suffer from pain. To overcome the pain of the disease, there have been renewed requirements to understand the novel molecular mechanisms of the pain in SCD.

Methods

We concisely summarized the molecular mechanisms of SCD-related acute and chronic pain, focusing on potential drug targets to treat pain.

Results

Acute pain of SCD is caused by vaso-occulusive crisis (VOC), impaired oxygen supply or infarction-reperfusion tissue injuries. In VOC, inflammatory cytokines include tryptase activate nociceptors and transient receptor potential vanilloid type 1. In tissue injury, the secondary inflammatory response is triggered and causes further tissue injuries. Tissue injury generates cytokines and pain mediators including bradykinin, and they activate nociceptive afferent nerves and trigger pain. The main causes of chronic pain are from extended hyperalgesia after a VOC and central sensitization. Neuropathic pain could be due to central or peripheral nerve injury, and protein kinase C might be associated with the pain. In central sensitization, neuroplasticity in the brain and the activation of glial cells may be related with the pain.

Discussion

In this review, we summarized the molecular mechanisms of SCD-related acute and chronic pain. The novel treatments targeting the disease mechanisms would interrupt complications of SCD and reduce the pain of the SCD patients.

Chronic Pain Does Not Impact Baseline Circulating Cytokine Levels in Adults with Sickle Cell Disease

Chronic pain affects 50% of adults with sickle cell disease (SCD). Although inflammation is thought to contribute to the pathogenesis of chronic pain, no studies have examined the differences in circulating cytokines between patients with SCD with and without chronic pain. We performed an observational cohort study using blood and urine samples from adults with SCD with and without chronic pain at their usual state of health. We tested the hypothesis that, compared to those without chronic pain, those with chronic pain would have significantly higher baseline circulating proinflammatory cytokines. A total of 61 adults with SCD, 40 with chronic pain and 21 without chronic pain were tested. When SCD patients with chronic pain were compared to those without chronic pain, no significant differences in cytokine levels were noted. The variables most associated with the diagnosis of chronic pain in this population were opioid dose and subject age.

A Comprehensive Review of the Treatment and Management of Pain in Sickle Cell Disease

PURPOSE OF REVIEW

Sickle cell disease (SCD) is a hematological disorder which leads to serious complications in multiple organ systems. While significant research has addressed many of the effects of acute pain episodes and end-organ damage connected to this disease, little has approached the chronic pain state associated with this condition.

RECENT FINDINGS

Associated chronic pain represents a significant detractor from the quality of life experienced by these patients, affecting over half of those with SCD on more days than not. Current treatment typically is centered upon preventing and responding to acute vasoocclusive crises, presumably because this is the most common reason for hospitalization in these patients. The lack of management of chronic pain symptoms leaves many with SCD in a state of suffering. In this review, the treatment methodologies of SCD patients are examined including alternative treatments, both pharmaceutical and non-pharmaceutical, as well as procedural approaches specifically aimed at reducing chronic pain in these patients.

Sensitivities to Thermal and Mechanical Stimuli: Adults With Sickle Cell Disease Compared to Healthy, Pain-Free African American Controls

Evidence supports^, but is inconclusive that sensitization contributes to chronic pain in some adults with sickle cell disease (SCD). We determined the prevalence of pain sensitization among adults with SCD pain compared with pain-free healthy adults. In a cross sectional, single session study of 186 African American outpatients with SCD pain (age 18-74 years, 59% female) and 124 healthy age, gender, and race matched control subjects (age 18-69 years, 49% female), we compared responses to standard thermal (Medoc TSA II) and mechanical stimuli (von Frey filaments). Although we observed no significant differences in thermal thresholds between controls and patients, patients with SCD had lower pain thresholds to mechanical stimuli and reported higher pain intensity scores to all thermal and mechanical stimuli at a non-painful body site. Compared with controls, about twice as many patients with SCD showed sensitization: 12% versus 23% at the anterior forearm site (P = .02), and 16% versus 32% across 3 tested sites (P = .004). Among patients with SCD, 18% exhibited some element of central sensitization. Findings indicate that persistent allodynia and hyperalgesia can be part of the SCD pain experience and should be considered when selecting therapies for SCD pain. PERSPECTIVE: Compared with matched healthy controls, quantitative sensory testing in adults with pain and sickle cell disease (SCD) demonstrates higher prevalence of sensitization, including central sensitization. The findings of allodynia and hyperalgesia may indicate neuropathic pain and could contribute to a paradigm shift in assessment and treatment of SCD pain.

Updated mechanisms underlying sickle cell disease-associated pain

Sickle cell disease (SCD) is one of the most common severe genetic diseases around the world. A majority of SCD patients experience intense pain, leading to hospitalization, and poor quality of life. Opioids form the bedrock of pain management, but their long-term use is associated with severe side effects including hyperalgesia, tolerance and addiction. Recently, excellent research has shown some new potential mechanisms that underlie SCD-associated pain. This review focused on how transient receptor potential vanilloid 1, endothelin-1/endothelin type A receptor, and cannabinoid receptors contributed to the pathophysiology of SCD-associated pain. Understanding these mechanisms may open a new avenue in managing SCD-associated pain and improving quality of life for SCD patients.

Effect of chronic opioid therapy on pain and survival in a humanized mouse model of sickle cell disease

Chronic morphine treatment leads to decreased survival in control mice, but not in sickle mice. Chronic morphine treatment leads to hyperalgesia in sickle mice, but does not lead to analgesic tolerance.

Preliminary evidence that hydroxyurea is associated with attenuated peripheral sensitization in adults with sickle cell disease

Introduction:

Hydroxyurea (HU) is a drug that targets the underlying pathophysiology of sickle cell disease (SCD); however, it continues to be an underutilized treatment for adults. Previous research suggests that HU treatment can result in fewer hospital contacts for acute vaso-occlusive pain crises (VOC). Hydroxyurea's impact on non-VOC pain, however, is not well established.

Objectives:

This study examined whether HU moderated patterns of static and dynamic pain processing and clinical pain in SCD individuals.

Methods:

Fifty-eight patients with SCD (N taking HU = 17) underwent quantitative sensory testing (QST) and completed twice daily symptom diaries for 12 weeks. Quantitative sensory testing established thermal threshold and tolerance, mechanical thresholds, and thermal and mechanical temporal summation of pain.

Results:

Groups did not differ in age, sex, or opioid use. After controlling for morphine use, QST results showed that participants taking HU had higher heat and mechanical pain thresholds (static QST measures) but not thermal and mechanical temporal summation (dynamic QST measures). Participants taking HU also reported lower VOC pain compared with SCD participants not taking HU; however, HU did not moderate non-VOC clinical pain ratings.

Conclusion:

Findings cautiously suggest that HU acts on pain hypersensitivity and VOC pain, rather than inhibiting pain facilitation and non-VOC pain. These differences may reflect HU's influence on peripheral rather than central sensitization. Future research is warranted to replicate these findings in a larger sample and determine whether early HU administration can prevent peripheral sensitization in SCD individuals.

AAAPT Diagnostic Criteria for Acute Sickle Cell Disease Pain

Acute pain episodes are the most common complication in patients with sickle cell disease (SCD). Classically attributed to vaso-occlusion, recent insights suggest that chronic pain may also contribute to the pathogenesis of acute pain episodes, which adds complexity to their diagnosis and management. A taxonomy, or classification system, for acute pain in patients with SCD would aid research efforts and enhance clinical care. To meet this need, the Analgesic, Anesthetic, and Addiction Clinical Trial Translations, Innovations, Opportunities, and Networks public-private partnership with the U.S. Food and Drug Administration, the American Pain Society, and the American Academy of Pain Medicine formed the Analgesic, Anesthetic, and Addiction Clinical Trial Translations, Innovations, Opportunities, and Networks-American Pain Society-American Academy of Pain Medicine Pain Taxonomy initiative. One of the goals of this initiative was to develop taxonomies for acute pain disorders, including SCD. To accomplish this, a working group of experts in SCD and pain was convened. Based on available literature and expert opinion, the working group used a 5-dimenional structure (diagnostic criteria, common features, modulating factors, impact/functional consequences, and putative mechanisms) to develop an acute pain taxonomy that is specific to SCD. As part of this, a set of 4 diagnostic criteria, with 2 modifiers to account for the influence of chronic pain, are proposed to define the types of acute pain observed in patients with SCD. PERSPECTIVE: This article presents a taxonomy for acute pain in patients with SCD. This taxonomy could help to standardize definitions of acute pain in clinical studies of patients with SCD.

Predictive Ability of Intermittent Daily Sickle Cell Pain Assessment: The PiSCES Project

Background

Pain diary assessment in sickle cell disease (SCD) may be expensive and impose a high respondent burden.

Objective

To report whether intermittent assessment could substitute for continuous daily pain assessment in SCD.

Design

Prospective cohort study.

Setting

Academic and community practices in Virginia. Patients. A total of 125 SCD patients age 16 years or older in the Pain in Sickle Cell Epidemiology Study. Measurements. Using pain measures that summarized all diaries as the gold standard, we tested the statistical equivalence of four alternative strategies that summarized diaries only from the week prior or the month prior to study completion; one week per month; or one day per week (random day). Summary measures included percent pain days, percent crisis days (self-defined), mean pain (0-9 Likert scale) on all days, and mean pain on pain days. Equivalence tests included comparisons of means, regression intercepts, and slopes, as well as measurement of R2.

Results

Compared with the gold standard, the one-day-per-week and one-week-per-month strategies yielded statistically equivalent means of six summary pain measures, and the week prior and month prior yielded equivalent means as some of the measures. Regression showed statistically equivalent slopes and intercepts to the gold standard using one-day-per-week and one-week-per-month strategies for percent pain days and percent crisis days, but almost no other equivalence. R2 values ranged from 0.64 to 0.989.

Conclusions

It is possible to simulate five- to six-month daily assessment of pain in SCD. Either one-day-per-week or one-week-per-month assessment yields an equivalent mean and fair regression equivalence.