Sickle cell disease: a natural model of acute and chronic pain

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.

High-impact chronic pain in sickle cell disease: insights from the Pain in Sickle Cell Epidemiology Study (PiSCES)

ABSTRACT

The US National Pain Strategy recommends identifying individuals with chronic pain (CP) who experience substantial restriction in work, social, or self-care activities as having high-impact chronic pain (HICP). High-impact chronic pain has not been examined among individuals with CP and sickle cell disease (SCD). We analyzed data from 63 individuals with SCD and CP who completed at least 5 months of pain diaries in the Pain in Sickle Cell Epidemiology Study (PiSCES). Forty-eight individuals met the definition for HICP, which was operationalized in this study as reporting pain interference on more than half of diary days. Compared with individuals without HICP, individuals with HICP experienced higher mean daily pain intensity, particularly on days without crises. They also experienced a greater proportion of days with pain, days with healthcare utilization, and days with home opioid use and higher levels of stress. They did not have a statistically significantly higher proportion of days with crises or experience higher mean daily pain intensity on days with crises. Individuals with HICP experienced worse physical functioning and worse physical health compared with those without HICP, controlling for mean pain intensity, age, sex, and education. The results of this study support that HICP is a severely affected subgroup of those with CP in SCD and is associated with greater pain burden and worse health outcomes. The findings from this study should be confirmed prospectively in a contemporary cohort of individuals with SCD.

Antioxidant supplementation for sickle cell disease

BACKGROUND

Sickle cell disease (SCD) refers to a group of genetic disorders characterized by the presence of an abnormal haemoglobin molecule called haemoglobin S (HbS). When subjected to oxidative stress from low oxygen concentrations, HbS molecules form rigid polymers, giving the red cell the typical sickle shape. Antioxidants have been shown to reduce oxidative stress and improve outcomes in other diseases associated with oxidative stress. Therefore, it is important to review and synthesize the available evidence on the effect of antioxidants on the clinical outcomes of people with SCD.

OBJECTIVES

To assess the effectiveness and safety of antioxidant supplementation for improving health outcomes in people with SCD.

SEARCH METHODS

We used standard, extensive Cochrane search methods. The latest search date was 15 August 2023.

SELECTION CRITERIA

We included randomized and quasi-randomized controlled trials comparing antioxidant supplementation to placebo, other antioxidants, or different doses of antioxidants, in people with SCD.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data, assessed the risk of bias and certainty of the evidence, and reported according to Cochrane methodological procedures.

MAIN RESULTS

The review included 1609 participants in 26 studies, with 17 comparisons. We rated 13 studies as having a high risk of bias overall, and 13 studies as having an unclear risk of bias overall due to study limitations. We used GRADE to rate the certainty of evidence. Only eight studies reported on our important outcomes at six months. Vitamin C (1400 mg) plus vitamin E (800 mg) versus placebo Based on evidence from one study in 83 participants, vitamin C (1400 mg) plus vitamin E (800 mg) may not be better than placebo at reducing the frequency of crisis (risk ratio (RR) 1.18, 95% confidence interval (CI) 0.64 to 2.18), the severity of pain (RR 1.33, 95% CI 0.40 to 4.37), or adverse effects (AE), of which the most common were headache, nausea, fatigue, diarrhoea, and epigastric pain (RR 0.56, 95% CI 0.31 to 1.00). Vitamin C plus vitamin E may increase the risk of SCD-related complications (acute chest syndrome: RR 2.66, 95% CI 0.77 to 9.13; 1 study, 83 participants), and increase haemoglobin level (median (interquartile range) 90 (81 to 96) g/L versus 93.5 (84 to 105) g/L) (1 study, 83 participants) compared to placebo. However, the evidence for all the above effects is very uncertain. The study did not report on quality of life (QoL) of participants and their caregivers, nor on frequency of hospitalization. Zinc versus placebo Zinc may not be better than placebo at reducing the frequency of crisis at six months (rate ratio 0.62, 95% CI 0.17 to 2.29; 1 study, 36 participants; low-certainty evidence). We are uncertain whether zinc is better than placebo at improving sickle cell-related complications (complete healing of leg ulcers at six months: RR 2.00, 95% CI 0.60 to 6.72; 1 study, 34 participants; very low-certainty evidence). Zinc may be better than placebo at increasing haemoglobin level (g/dL) (MD 1.26, 95% CI 0.44 to 1.26; 1 study, 36 participants; low-certainty evidence). The study did not report on severity of pain, QoL, AE, and frequency of hospitalization. N-acetylcysteine versus placebo N-acetylcysteine (NAC) 1200 mg may not be better than placebo at reducing the frequency of crisis in SCD, reported as pain days (rate ratio 0.99 days, 95% CI 0.53 to 1.84; 1 study, 96 participants; low-certainty evidence). Low-certainty evidence from one study (96 participants) suggests NAC (1200 mg) may not be better than placebo at reducing the severity of pain (MD 0.17, 95% CI -0.53 to 0.87). Compared to placebo, NAC (1200 mg) may not be better at improving physical QoL (MD -1.80, 95% CI -5.01 to 1.41) and mental QoL (MD 2.00, 95% CI -1.45 to 5.45; very low-certainty evidence), reducing the risk of adverse effects (gastrointestinal complaints, pruritus, or rash) (RR 0.92, 95% CI 0.75 to 1.14; low-certainty evidence), reducing the frequency of hospitalizations (rate ratio 0.98, 95% CI 0.41 to 2.38; low-certainty evidence), and sickle cell-related complications (RR 5.00, 95% CI 0.25 to 101.48; very low-certainty evidence), or increasing haemoglobin level (MD -0.18 g/dL, 95% CI -0.40 to 0.04; low-certainty evidence). L-arginine versus placebo L-arginine may not be better than placebo at reducing the frequency of crisis (monthly pain) (RR 0.71, 95% CI 0.26 to 1.95; 1 study, 50 participants; low-certainty evidence). However, L-arginine may be better than placebo at reducing the severity of pain (MD -1.41, 95% CI -1.65 to -1.18; 2 studies, 125 participants; low-certainty evidence). One participant allocated to L-arginine developed hives during infusion of L-arginine, another experienced acute clinical deterioration, and a participant in the placebo group had clinically relevant increases in liver function enzymes. The evidence is very uncertain whether L-arginine is better at reducing the mean number of days in hospital compared to placebo (MD -0.85 days, 95% CI -1.87 to 0.17; 2 studies, 125 participants; very low-certainty evidence). Also, L-arginine may not be better than placebo at increasing haemoglobin level (MD 0.4 g/dL, 95% CI -0.50 to 1.3; 2 studies, 106 participants; low-certainty evidence). No study in this comparison reported on QoL and sickle cell-related complications. Omega-3 versus placebo Very low-certainty evidence shows no evidence of a difference in the risk of adverse effects of omega-3 compared to placebo (RR 1.05, 95% CI 0.74 to 1.48; 1 study, 67 participants). Very low-certainty evidence suggests that omega-3 may not be better than placebo at increasing haemoglobin level (MD 0.36 g/L, 95% CI -0.21 to 0.93; 1 study, 67 participants). The study did not report on frequency of crisis, severity of pain, QoL, frequency of hospitalization, and sickle cell-related complications.

AUTHORS' CONCLUSIONS

There was inconsistent evidence on all outcomes to draw conclusions on the beneficial and harmful effects of antioxidants. However, L-arginine may be better than placebo at reducing the severity of pain at six months, and zinc may be better than placebo at increasing haemoglobin level. We are uncertain whether other antioxidants are beneficial for SCD. Larger studies conducted on each comparison would reduce the current uncertainties.

Opioid Use Among Children and Adults With Sickle Cell Disease in North Carolina Medicaid Enrollees in the Era of Opioid Harm Reduction

Adults and children with sickle cell disease (SCD) are predominantly African American, with pain-related health disparities. We examined opioid prescription fill patterns in adults and children with SCD and compared factors associated with fills in North Carolina Medicaid enrollees. Our retrospective cohort study included 955 enrollees diagnosed with SCD having at least one opioid fill. Associations were measured between two cohorts (12 and 24 mo of continuous enrollment) for the following characteristics: sex, age, enrollee residence, hydroxyurea adherence, comanagement, enrollment in Community Care North Carolina, prescription for short versus short and long-acting opioids, and emergency department reliance. The majority of individuals did not have an opioid claim over a 12 or 24-month period. Claims increased at ages 10 to 17, peaking at ages 18 to 30. The increased number of claims was associated with the following factors: increasing age, male, short versus long-acting opioids, and Medicaid enrollment for 24 versus 12 months. Community Care North Carolina enrollees in the 12-month cohort had higher opioid days of supply per month; the inverse was true of the 24-month cohort.

A Mixed-Methods Evaluation of a Project ECHO Program for the Evidence-Based Management of Sickle Cell Disease

Sickle cell disease (SCD) is a group of chronic, genetic disorders of the red blood cells with significant gaps in access to evidence-based clinical care. Sickle Treatment and Outcomes Research in the Midwest (STORM), a provider network, utilized Project ECHO (Extension for Community Health Outcomes), a telementoring model, to deliver evidence-based education about SCD management. The purpose of this mixed-methods study is to evaluate the utility of Project ECHO as an educational strategy for healthcare providers treating children and adults with SCD. Annual evaluations were administered to STORM TeleECHO participants from 2016 to 2021. Survey data showed a statistically significant change in self-reported provider confidence in the ability to provide care for adult patients with SCD; identify suitable candidates for disease-modifying therapies; and confidence to prescribe disease-modifying therapies. Participants who attended at least 10 sessions were invited to participate in a semi-structured interview. Qualitative data were analyzed using thematic analysis and several themes emerged about the benefits, including (1) increased confidence, (2) integrated best-practice care, (3) connection to provider network and access to experts, (4) high-quality educational presentations and (5) opportunities for collaboration and a sense of community. This suggests that Project ECHO is accessible and leads to increased confidence in providers caring for individuals with SCD. Overall, participant knowledge gains successfully demonstrated the utility of Project ECHO as an educational resource for providers.

Agreement between youth and caregiver report of pain and functioning in pediatric sickle cell disease: PedsQL sickle cell disease module

ABSTRACT

Pain is a primary symptom of sickle cell disease (SCD) and is often severe and chronic. To treat SCD-related pain, proper assessment of SCD pain among youth, including the degree of concordance or agreement between youth and caregiver reports of pain, is essential but has not yet been adequately evaluated. In this study, 525 youth with SCD and their parents were evaluated as part of the Sickle Cell Clinical Research and Intervention Program (SCCRIP) to examine pain rating concordance and predictors of concordance. Youth and parents completed the Pediatric Quality of Life Inventory Sickle Cell Disease module (PedsQL-SCD) to measure pain, pain interference, and pain-related constructs. Disease, clinical, and demographic variables were obtained from the SCCRIP database. Intraclass correlations demonstrated moderate-to-poor consistency between youth and caregiver reports of pain and pain interference (ICCs range from 0.17 to 0.54). Analysis of covariance and regression models found that patient age, frequency of hospitalizations and emergency department (ED) visits, economic hardship, and fetal hemoglobin levels were significantly associated with varying pain-rating agreement levels among parent proxy and child self-report pain. Concordance of pain assessments among youth with SCD and their caregivers using the PedsQL-SCD Module was moderate at best, corroborating prior research. Youth factors predicting discordance among pain-related factors included increased ED visits, older age, and female sex. Collectively, these results bolster the use of integrated pain assessments to reduce parent-child discrepancies, thereby improving the adequacy of SCD-related pain assessment and treatment.

Nurses' Attitudes Concerning Analgesia Administration for Pediatric Patients with Sickle Cell Disease in Jordan: A Cross-Sectional Study

BACKGROUND

Pain management of vaso-occlusive crises is a fundamental priority in the lifelong care of children and adolescents with sickle cell disease.

AIM

This study examined nurses' attitudes towards caring for children with sickle cell disease (SCD) and SCD pain management in those with vaso-occlusive pain.

METHOD

A structured, self-reporting survey was provided to a convenience sample of 298 nurses across 10 hospitals serving Jordan's northern and middle regions. Descriptive and inferential statistics were applied for data analysis.

RESULTS

Most nurses (77%) perceived their experience caring for children with SCD as positive. Many nurses (65%) felt frustrated about caring for these children during painful episodes. Participants identified workload and inadequate time as limiting their ability to address the analgesic needs of children with SCD. Receiving structured education specialized in pain management and more years of experience in nursing significantly predicted less hesitancy in administering opioid-based analgesia.

CONCLUSIONS

The results of this study provided further insight into factors that potentially contribute to vaso-occlusive pain crises frequently being poorly managed and inadequately addressed among pediatric patients. Nurses' attitudes and understanding of SCD pain management must be addressed to advance the clinical practice of managing pain in children with SCD.

Validity and reliability of the WHOQOL-BREF in the measurement of the quality of life of Sickle disease patients in Bahrain

Background

Limited attention is devoted to the improvement of the quality of life of patients suffering from the negative consequences of Sickle cell disease (SCD). Our study focuses on the evaluation of the performance of the WHOQOL-BREF as a tool to measure the quality of life of SCD Patients in Bahrain.

Methods

We conducted a cross-sectional study that enrolled 273 SCD patients selected using a simple random sampling technique from primary health-care centers in Bahrain in 2019. A designed questionnaire including the WHOQOL-BREF was filled by the patients in the health centers. The reliability of the WHOQOL-BREF was assessed by standardized Cronbach's alpha coefficient, and the validity was measured by convergent validity, principal component analysis and confirmatory factor analysis.

Results

The WHOQOL-BREF had good internal consistency as Cronbach's alpha coefficient for the overall scale was 0.91. The convergent validity results indicated that the correlation coefficients values for all scale domains are significantly correlated at α < 0.01. Confirmatory factor analysis found that the four-domain structure produced a robust fit to the data.

Conclusion

The WHOQOL-BREF tool has high internal consistency and validity in assessing the quality of life of Sickle Disease patients in Bahrain.

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.

Feasibility and Acceptability of Online Recruitment and an Online Brief Mindfulness Intervention Among Patients With Sickle Cell Disease

Background Pain among young adult patients with sickle cell disease (PWSCD) is a highly significant public health problem associated with reduced quality of life. Due to issues uniquely affecting PWSCD, including distrust of research, challenging life situations, debilitating pain, stigma, and logistical challenges (e.g., child or elder care and transportation), SCD researchers often find it challenging to meet sample size and enrollment targets. To our knowledge, all known SCD studies have solely recruited participants in person (e.g., clinics and local organizations) and utilized lengthy interventions with suboptimal recruitment and retention results. Newer recruitment methods, such as online recruitment, need to be explored for research among PWSCD. In this pilot project, we sought to address these challenges by investigating: 1) a novel method of using online outreach to recruit/enroll young PWSCD and 2) a novel, brief online mindfulness intervention adapted from Mindfulness-Oriented Recovery Enhancement (MORE): Mini-MORE designed to treat pain among PWSCD.  Methods Participants (N = 32) were recruited online (e.g., paid advertisements on Facebook and NextDoor; free advertisements on Facebook groups and Reddit) and screened by phone from October 25 to November 8, 2022. Participants watched an online Mini-MORE video. Immediately before and after watching the video, participants rated their pain intensity and unpleasantness on an 11-point numeric rating scale (NRS). Afterward, participants were emailed an individualized link to additional audio recordings for ongoing practice. Immediately before and after accessing the additional recordings, participants rated their pain intensity, anxiety, and depression on an 11-point NRS. T-tests were used to examine the impact of Mini MORE on outcomes at two-time points. Results A total of 84 participants completed the self-screening. The majority of self-screeners resulted from free posts in Facebook groups (77%), Reddit (1%), and Craigslist (6%). Thirty-two (32) eligible participants agreed to join a Zoom meeting to watch the video. The entire Mini-MORE video was viewed by 31 of 32 participants (97%). Pain intensity decreased by 1.7 points (p<0.001, Cohen's d=2.19), and pain unpleasantness decreased by 2.1 points (p<0.001, Cohen's d=2.20). Listening to the supplemental recordings was associated with significant, immediate decreases in pain intensity by 1.3 points (p=0.015, Cohen's d=2.05), anxiety by 1.8 points (p=0.022, Cohen's d=3.10), and depression by 1.74 points (p=0.019, Cohen's d=2.94). Conclusions Results suggest that online methods are feasible in recruiting and enrolling young PWSCD, and the online Mini-MORE intervention is acceptable among PWSCD. Future research is needed to assess whether Mini-MORE is associated with decreased pain symptomology in young PWSCD.

Presentations and outcomes among sickle cell disease patients with COVID-19 at a large southern healthcare system

OBJECTIVES

Compared with the general population, patients with sickle cell disease (SCD) typically have substantially reduced life expectancies. It is unclear whether SCD patients who acquire COVID-19 have higher rates of complications and mortality than the general population. We sought to elucidate COVID-19 presentation and outcomes in patients with SCD.

METHODS

Using retrospective chart review, we evaluated demographic characteristics, presenting symptoms, chest imaging findings, blood transfusion requirements, need for mechanical ventilation or pressor support, medication administration (including remdesivir and dexamethasone), and survival among individuals with SCD hospitalized with COVID-19 from March 2020 to December 2021.

RESULTS

Among 72 SCD patients, increased pain was the most common presenting symptom followed by cough, fever, and dyspnea. Thirty-seven (44%) received simple transfusion and 14 (17%) underwent exchange transfusion. Lung imaging findings suggestive of COVID-19 were observed in 27 (37%) patients; 21 (29%) patients were treated with remdesivir and 26 (35%) received dexamethasone. Three patients (4%) required mechanical ventilation and pressor support; all three died from COVID complications.

CONCLUSIONS

Pain is the most common presenting symptom in SCD patients with COVID-19. We observed a mortality rate higher than that among the general population among patients who required mechanical ventilation and pressor support.

Patient and Caregiver Perspectives on Care-Seeking During a Vaso-Occlusive Crisis in Sickle Cell Disease: Results from Qualitative Interviews in Canada

PURPOSE

There is little research on care-seeking preferences during active pain crises for sickle cell disease (SCD) patients and their caregivers. The objective of this study was to identify relevant, patient or caregiver narratives of the pain crisis experience, to understand the factors that contribute to care-seeking during a pain crisis, and to identify preferences when making care-seeking decisions during a pain crisis.

PATIENTS AND METHODS

Qualitative semi-structured interviews were conducted with Canadian residents with a self-reported SCD diagnosis, who were either ≥18 years of age or an adolescent between the ages of 12-18. Interviews were hosted virtually, audio-recorded, and transcribed verbatim.

RESULTS

A total of 23 individuals participated (74% female; 26% male), including six adolescents with parent dyads and 11 adults. Almost all (N = 21, 91.3%) participants were Black/African American. Participants mentioned many factors that influenced care-seeking decisions, mainly the symptom and pain experience; institutional factors (waiting time, the presence of and adherence to treatment guidelines, and the empathy or racial bias felt from medical staff); and subject-level factors (age and a flexibility in daily responsibilities).

CONCLUSION

This study identified important institutional and subject-level considerations involved in care-seeking decisions. Most importantly, this study highlights the racial stigma faced by many patients when care-seeking in the ER and the lack of care protocol implemented, which hinders care-seeking in a dedicated medical facility. From the patient perspective, these are clear gaps to fill to encourage patients to seek and receive the care they deserve.

The Efficacy of Marijuana Use for Pain Relief in Adults With Sickle Cell Disease: A Systematic Review

Sickle Cell Disease (SCD) is a disease that affects many around the world and often accounts for frequent hospital admissions every year, secondary to uncontrolled pain. Marijuana is increasingly being used for its medicinal ability to treat pain in chronic medical conditions. Therefore, it is imperative to determine how effective it would be in providing pain relief to patients with SCD. We systematically screened five databases for relevant data: PubMed, Medline, PubMed Central (PMC), Cochrane Library, and Google Scholar. The inclusion and exclusion criteria were implemented. A quality appraisal was then done using the Cochrane Bias assessment for randomized controlled trials (RCTs), Newcastle-Ottawa tool for observational studies, and Scale for the Assessment of Narrative Review Articles (SANRA) checklist for traditional review articles. From seven articles, information was gathered; one systematic review, one RCT, two surveys, one cross-sectional study, one retrospective study, and one questionnaire-based study. Our review concluded that based on the literature assessed, marijuana use in SCD patients either worsened their painful crises or offered little to no help compared to opioids or hydroxyurea usage. There were limited RCTs published in addition to papers investigating the long-term effects of marijuana use in SCD. We hope that further data is gathered in these areas to sufficiently address whether cannabis use is efficacious for pain relief in patients with SCD.

Distracting Through Procedural Pain and Distress Using Virtual Reality and Guided Imagery in Pediatric, Adolescent, and Young Adult Patients: Randomized Controlled Trial

BACKGROUND

Children with acute and chronic illness undergo frequent, painful, and distressing procedures.

OBJECTIVE

This randomized controlled trial was used to evaluate the effectiveness of guided imagery (GI) versus virtual reality (VR) on the procedural pain and state anxiety of children and young adults undergoing unsedated procedures. We explored the role of trait anxiety and pain catastrophizing in intervention response.

METHODS

Children and young adults were recruited from the hematology, oncology, and blood and marrow transplant clinics at a children's hospital. Each study participant completed the GI and VR intervention during separate but consecutive unsedated procedures. Self-report measures of pain and anxiety were completed before and after the procedures.

RESULTS

A total of 50 participants (median age 13 years) completed both interventions. GI and VR performed similarly in the management of procedural pain. Those with high pain catastrophizing reported experiencing less nervousness about pain during procedures that used VR than those using GI. State anxiety declined pre- to postprocedure in both interventions; however, the decrease reached the level of significance during the VR intervention only. Those with high trait anxiety had less pain during GI.

CONCLUSIONS

In our sample, VR worked as well as GI to manage the pain and distress associated with common procedures experienced by children with acute or chronic illnesses. Children who are primed for pain based on beliefs about pain or because of their history of chronic pain had a better response to VR. GI was a better intervention for those with high trait anxiety.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04892160; https://clinicaltrials.gov/ct2/show/NCT04892160.

Non-crisis related pain occurs in adult patients with sickle cell disease despite chronic red blood cell exchange transfusion therapy

BACKGROUND

Chronic red blood cell transfusions reduce acute care utilization for sickle cell disease (SCD) pain. However, little is known about whether chronic transfusions treat or prevent the development of non-crisis pain. We investigated patient-report of pain in adults with SCD receiving chronic exchange transfusions (CET) compared to adults not on CET with similar disease characteristics.

STUDY METHOD AND DESIGN

Eleven participants receiving chronic exchange transfusion (CET) for at least one year were compared to 33 participants not receiving CET. Participants completed validated patient-reported outcomes regarding pain impact and quality of life at regularly scheduled visits or before CET. One year of health care utilization and opioid prescriptions were examined.

RESULTS

After 1:1 propensity matching was performed for age, genotype, WBC and neutrophil counts, patients on CET had lower Pain Impact scores (-5.1, p = 0.03) and higher Neuropathic (7.4, p < 0.001) and Nociceptive Pain Quality (3.7, p < 0.001) scores, all indicating worse pain. However, CET was associated with a reduction in annual all cause admissions (-3.1, p < 0.001), length of stay (-2.1 days, p < 0.001) and ED visits (-2.7, p < 0.001). CET was not associated with differences in opioids dispensed.

CONCLUSIONS

After adjusting for disease characteristics, CET was associated with worse pain impact and neuropathic and nociceptive pain quality, lower health care utilization and with similar levels of opioids dispensed. This data suggest that CET may reduce hospitalizations for acute pain but may not adequately treat nociceptive or neuropathic pain in SCD.

Gabapentin for acute pain in sickle cell disease: A randomized double-blinded placebo-controlled phase II clinical trial

Pain in sickle cell disease (SCD) can have a neuropathic component. This randomized phase II double-blinded placebo-controlled study evaluated the efficacy of gabapentin in reducing pain and opioid consumption (morphine-equivalent dose [MED]) during acute vaso-occlusive crisis (VOC). Of 90 patients aged 1-18 years with VOC pain, 45 were randomized to a single gabapentin dose (15 mg/kg) and 45 to placebo, in addition to standard treatment; 42 and 44 patients were evaluable in the gabapentin and placebo arms, respectively. A decrease in pain of ≥33% was reported in 68% of patients in the gabapentin arm and 60% of those in the placebo arm (one-sided p = 0.23). The median MED (mg/kg) in the gabapentin (0.12) and placebo arms (0.13) was similar (p = 0.9). However, in the subset of patients with the HbSS genotype (n = 45), the mean (SD) absolute pain score decrease by the time of discharge was significantly greater in the gabapentin arm (5.9 [3.5]) than in the placebo arm (3.6 [3.3]) (p = 0.032). Pain scores in the overall study population were not significantly reduced when gabapentin was added to standard treatment; however, gabapentin benefited individuals with the more severe genotype, HbSS, during acute VOC. Larger, prospective studies are needed to confirm these findings.

Identifying elevated risk for future pain crises in sickle-cell disease using photoplethysmogram patterns measured during sleep: A machine learning approach

Transient increases in peripheral vasoconstriction frequently occur in obstructive sleep apnea and periodic leg movement disorder, both of which are common in sickle cell disease (SCD). These events reduce microvascular blood flow and increase the likelihood of triggering painful vaso-occlusive crises (VOC) that are the hallmark of SCD. We recently reported a significant association between the magnitude of vasoconstriction, inferred from the finger photoplethysmogram (PPG) during sleep, and the frequency of future VOC in 212 children with SCD. In this study, we present an improved predictive model of VOC frequency by employing a two-level stacking machine learning (ML) model that incorporates detailed features extracted from the PPG signals in the same database. The first level contains seven different base ML algorithms predicting each subject's pain category based on the input PPG characteristics and other clinical information, while the second level is a meta model which uses the inputs to the first-level model along with the outputs of the base models to produce the final prediction. Model performance in predicting future VOC was significantly higher than in predicting VOC prior to each sleep study (F1-score of 0.43 vs. 0.35, p-value <0.0001), consistent with our hypothesis of a causal relationship between vasoconstriction and future pain incidence, rather than past pain leading to greater propensity for vasoconstriction. The model also performed much better than our previous conventional statistical model (F1 = 0.33), as well as all other algorithms that used only the base-models for predicting VOC without the second tier meta model. The modest F1 score of the present predictive model was due in part to the relatively small database with substantial imbalance (176:36) between low-pain and high-pain subjects, as well as other factors not captured by the sleep data alone. This report represents the first attempt ever to use non-invasive finger PPG measurements during sleep and a ML-based approach to predict increased propensity for VOC crises in SCD. The promising results suggest the future possibility of embedding an improved version of this model in a low-cost wearable system to assist clinicians in managing long-term therapy for SCD patients.

Neuropathic Pain in Children with Sickle Cell Disease: The Hidden Side of the Vaso-Occlusive Crisis

The majority of hospitalizations of patients with sickle cell disease (SCD) are related to painful vaso-occlusive crises (VOCs). Although the pain of VOC is classically nociceptive, neuropathic pain (NP) has also been demonstrated in SCD patients. The aim of our study is to specify the prevalence of NP during VOCs in SCD children using a dedicated scale and to measure its characteristics. We performed a prospective study that included SCD children hospitalized for an acute VOC. The presence of NP was sought with the DN4 scale on the second and fourth days of hospitalization. A total of 54 SCD children were included in the study. Overall, 41% of the patients (n = 22) experienced neuropathic pain during the VOC, mostly at an early stage (Day 2). The median age, the sex ratio, the location of the pain, and the morphine consumption were similar for patients with and without NP. Our study shows that neuropathic pain is very common during VOCs in SCD children. The absence of identified risk factors should prompt us to be vigilant regardless of the patient's age, sex, and clinical presentation.

Pain in Youth With Sickle Cell Disease: A Report From the Sickle Cell Clinical Research and Intervention Program

OBJECTIVES

Pain is prevalent among youth with sickle cell disease (SCD). However, previous research has been limited by small sample sizes and lacked examinations of developmental differences in pain, which are critical to minimizing the development of chronic pain as youth transition into adulthood. The primary aim of the current study was to compare pain and pain interference across 4 developmental groups in a large sample of youth with SCD. The secondary aim was to identify risk factors for greater pain and pain interference.

MATERIALS AND METHODS

Utilizing a cross-sectional study design, the expression and predictors of pain and pain interference were compared across 4 developmental stages: toddlers/preschoolers (2 to 4 y), school-aged children (5 to 7 y), preadolescents (8 to 12 y), and adolescents (13 to 18 y). Participants included 386 youth with SCD and their caregivers.

RESULTS

Caregiver-reported pain and pain interference and youth-reported pain interference increased across developmental groups and plateaued approaching adolescence (multivariate analyses of variance P=0.002 for pain and P<0.001 for pain interference). Elevated fatigue, anxiety, and perceived difficulties with pain management were the most robust predictors of higher youth- and caregiver-reported pain (βs ranging from 0.15 to 0.68; P<0.001) and pain interference (βs ranging from 0.18 to 0.64; P<0.001).

DISCUSSION

Disease and treatment-related variables were not associated with pain. Self-reported pain was elevated in older versus younger developmental groups and was largely linked to anxiety, fatigue, and perceptions of pain management, thus highlighting the modifiable nature of factors influencing pain among youth with SCD.

Daily Cannabis Users with Sickle Cell Disease Show Fewer Admissions than Others with Similar Pain Complaints

Introduction: Previous studies have shown that cannabis use is common in adults with sickle cell disease (SCD), and that many patients report using cannabis to treat pain. Methods: We performed a cross-sectional study of adults with SCD and compared daily users of cannabis with others using validated patient-reported measures of pain and quality of life as well as opioid and health care utilization. Results: Daily cannabis users with SCD had worse pain episode severity scores than others (56.7 vs. 48.8, p=0.02) yet had 1.8 fewer annual admissions (p=0.01) and 1.2 fewer annual emergency room (ER) visits (p=0.01), and similar amounts of opioids dispensed to others after matching for age, gender, SCD genotype, hydroxyurea use, and pain impact scores. Conclusions: We show that people with SCD with more severe pain crisis are more likely to use daily cannabis, yet have lower rates of hospital admission and ER use as compared with others with similar disease severity and pain impact. Randomized controlled trials should be performed.

Mixed Bullous-Eczematous Contact Dermatitis From a Black Henna Tattoo in an African American Female With Sickle Cell Disease With Post-Dermatitis Pain

Traditionally practiced in East Asian and Southeast Asian countries, Henna tattooing has gained western popularity in creating temporary decorative patterns on the skin. Derived from the Lawsonia inermis shrub prevalent in Asia/Southeast Asia, the leaves of this plant are ground to create a paste with a brown pigment commonly called Mehndi or Henna which have deep-rooted cultural values/practices. The pure organic form of these compounds has few reported side effects. However, with gaining western popularity, synthetic additives to the natural paste to create color variation, shorten application times, and increase shelf-life have led to an increase in the incidence of adverse reactions. Namely attributed to synthetic compounds like para-phenylenediamine (PPD) or para-toluylenediamine, this synthetic type of mixture is called black henna. Although multiple types of adverse reactions with black henna have been documented as an eczematous type of reaction, few if any cases of adverse reactions of black henna affecting patients with sickle cell disease (SCD) have been documented. In this case, we aim to present an atypical mixed bullous-eczematous contact dermatitis reaction secondary to a PPD containing black henna dye applied to the skin of a patient with homozygous SCD. We intend to raise awareness of the deleterious cosmetic sequelae and chronic post-dermatitis pain manifestations which may arise in patients with SCD, as the popularity of black henna tattooing grows in the United States where SCD is one of the most prevalent hemoglobinopathies amongst black Americans.

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.

Prevalence and predictors of chronic pain intensity and disability among adults with sickle cell disease

Among 170 adults with sickle cell disease, we evaluated chronic pain impact and disability prevalence, assessed age and gender differences, and identified psychosocial predictors of chronic pain intensity and disability. Most participants had a high level of disability. Chronic pain intensity and disability were significantly associated with pain catastrophizing and chronic pain self-efficacy, and worsened with age. Further research is needed to confirm study findings and develop interventions, including palliative care approaches that address catastrophizing and disability, particularly for young women and middle-aged adults with sickle cell disease. Moreover, consistent clinical assessment of chronic pain and psychosocial health should be implemented.

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.

Phenylethanolamine N-methyltransferase gene polymorphisms associate with crisis pain in sickle cell disease patients

Aim: Phenylethanolamine N-methyltransferase (PNMT) catalyzes the conversion of sympathetic neurotransmitter norepinephrine to epinephrine. We examined the association of PNMT polymorphisms with acute and chronic pain in sickle cell disease (SCD). Methods: Utilization of emergency care owing to painful crisis was used as a marker for acute pain in 131 patients with SCD. Results: rs876493 A allele, rs2934965 T allele and rs2941523 G allele were significantly associated with decreased utilization (p ≤ 0.05). rs876493 A allele showed association with utilization in females (p = 0.003), not males (p = 0.803). rs2934965 T allele and rs2941523 G allele were predicted to cause loss of putative transcription factor binding sites. This is the first report of the association of PNMT polymorphisms with acute crisis pain in SCD. Together with our previous findings in catechol-o-methyltransferase, polymorphisms in catecholamine metabolizing enzymes appear to primarily influence acute pain in SCD.

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.

Interventions for treating neuropathic pain in people with sickle cell disease

BACKGROUND

Pain is the hallmark of sickle cell disease (SCD) and it can be severe, frequent and unpredictable. Although nociceptive pain is more common, at times, people with SCD may have neuropathic pain. The latter can occur due to peripheral or central nerve injury. This review is focused on identifying treatment of only painful sensory neuropathy in people with SCD.

OBJECTIVES

To determine the effectiveness and safety of any pharmacological or non-pharmacological therapies for treating neuropathic pain in people with SCD.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Haemoglobinopathies Trials Register, compiled from electronic database searches and handsearching of journals and conference abstract books. We also searched trial registries, the reference lists of relevant articles and reviews and contacted experts in the field.Date of last search: 31 January 2019.

SELECTION CRITERIA

Randomised controlled trials (RCTs) (parallel or cross-over in design), quasi-RCTs of pharmacological or non-pharmacological therapies for treating neuropathic pain in people with SCD compared to placebo or another intervention in any category (i.e. pharmacological or non-pharmacological).

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed all trials identified by the searches and extracted relevant data. Two authors independently assessed the risk of bias in the selected trials using the Cochrane risk of bias tool. Two review authors independently rated the quality of the evidence for each outcome using the GRADE guidelines.

MAIN RESULTS

One RCT of 22 participants with SCD, conducted in the USA was included in this review. Participants were randomly assigned to either pregabalin (n = 11) or placebo (n = 11). Oral pregabalin was administered at an initial dose of 75 mg twice daily. The drug was titrated at increments of 75 mg to a maximum of 600 mg daily or decreased by 75 mg per day if necessary, based on clinical presentation and pain level. Neuropathic pain was assessed using self-reports on the Leeds Assessment of Neuropathic Symptoms and Signs (S-LANNS) scale and the Neuropathic Pain Symptom Inventory (NPSI), where higher scores were indicative of more pain. Outcomes included self-reported pain, quality of life and withdrawal due to adverse effects measured at baseline and monthly for three months post-intervention. The overall risk of bias was low with a high risk of bias due to attrition.In relation to this reviews primary outcomes, for self-reported neuropathic pain relief, given the paucity of data, we are very uncertain whether there is a difference between the pregabalin and placebo groups at the end of three months as measured by the S-LANSS scale, mean difference (MD) -2.00 (95% confidence interval (CI) -9.18 to 5.18), or the NPSI scale, MD -11.10 (95% CI -33.97 to 11.77) (very low-quality evidence). There was no report of 'Patient Global Impression of Change' in the included trial.Although the mean quality of life scores (Short Form-36) at three months showed small increases in seven of the eight domains post-intervention in the pregabalin group as compared to the placebo group, this was very low-quality evidence and we are very uncertain whether pregabalin increases quality of life. Neither of our pre-defined outcomes of 'time to improvement of symptoms' or 'changes in sleep quality', were measured in the included trial.While treatment-related adverse effects appeared higher in pregabalin group than the placebo group at three months, this was very low-quality evidence and we are very uncertain whether there is a difference, RR 1.33 (95% CI 0.39 to 4.62) (very low-quality evidence). There was one withdrawal for adverse effects in the pregabalin group while three people withdrew or dropped out from the placebo group due to adverse effects and complications and hospitalisation related to SCD.

AUTHORS' CONCLUSIONS

The included trial provided very low-quality evidence. Self-reported pain relief was greater in the pregabalin group compared to the placebo control group but only using the S-LANSS scale and we are very unsure whether there is a difference. While the pregabalin group tended to have improved quality of life over the duration of the trial, this was very low-quality evidence and we are uncertain whether there is a difference. Adverse effects and withdrawals were similar across the treatment and placebo control group in trial. There are both insufficient trials addressing this review question and insufficient outcomes addressed in the single included RCT. Therefore, there is still a significant gap in evidence on interventions for neuropathic pain in people with SCD.

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.

Red blood cell transfusion therapy for sickle cell patients with frequent painful events

BACKGROUND

Recurrent pain events or chronic pain are among the most common complications of sickle cell disease. Despite attempts to maximize adherence to and dosing of hydroxyurea, some patients continue to suffer from pain. Our institution developed a program to initiate chronic red blood cell transfusions for one year in patients clinically deemed to have high healthcare utilization from sickle cell pain, despite being prescribed hydroxyurea.

PROCEDURE

An institutional review board approved retrospective study to evaluate the health outcomes associated with a one-year red blood cell transfusion protocol in sickle cell patients experiencing recurrent pain events as compared with the health outcomes for these patients in the one year prior to receiving transfusion therapy. We performed a matched-pair analysis using a Wilcoxon signed rank to determine the impact of transfusion therapy on clinic visits, emergency department visits, hospital admissions, hospitalization days, and opioid prescriptions filled.

RESULTS

One year of transfusion therapy significantly reduced the number of total emergency department visits for pain (6 vs 2.5 pain visits/year, P = 0.005), mean hospitalizations for pain (3.4 vs 0.9 pain admissions/year), and mean hospital days per year for pain crisis (23.5 vs 4.5, P = 0.0001), as compared with the one year prior to transfusion therapy. We identified no significant difference in opioid prescriptions filled during the year of transfusion therapy.

CONCLUSION

Patients with frequent pain episodes may benefit from one year of transfusion therapy.

Does sickle cell disease have a psychosomatic component? A particular focus on anxiety and depression

Sickle cell disease, an early-age genetic condition, encompasses a range of blood disorders with severe complications. This disease is characterized by the synthesis of abnormal hemoglobin molecules, which tend to polymerize due to their low solubility upon deoxygenation in the peripheral capillary beds, resulting in sickle-like red blood cells. Sickled cells lose their normal functioning and hemodynamic properties, leading to chronic fatigue as well as to episodes of painful crises. Over the last two decades, a growing body of clinical evidence has pointed out that these somatic complaints can give rise to neuropsychiatric disorders, among which anxiety and depression are the most common, that worsen the health-related quality of life in patients. At first glance, this somatic influence may be unsurprising, as both anxiety and depressive signs are prevalent in almost all chronic diseases. However, in the case of a genetic condition such as sickle cell disease whose somatic disturbances are predetermined, the fact that mood disorders can increase fatigue and pain through a psychosomatic component has attracted increasing attention. In this review, we address the hypothesis of a psychosomatic component in patients with sickle cell disease by underlining the most relevant clinical studies that have highlighted the existence of a bidirectional link between physical and psychological sequelae, which are reported to be relieved not only by pharmacological cotreatments but also by the concomitant application of cognitive behavioral therapy.

Interventions for treating neuropathic pain in people with sickle cell disease

This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:

To determine the effectiveness and safety of any pharmacological or non‐pharmacological therapies for treating neuropathic pain in people with SCD.

Pain-measurement tools in sickle cell disease: where are we now?

Pain is a complex multidimensional experience and the most common morbidity in patients with sickle cell disease (SCD). Tools to assess pain can be of use not only to guide pain treatment but also to provide insight into underlying pain neurobiology. Mechanisms of pain in SCD are multifactorial and are not completely elucidated. Although vaso-occlusion of microcirculation by sickled red cells is believed to be the underlying mechanism of acute vaso-occlusive pain, mechanisms for chronic pain and the transition from acute to chronic pain are under investigation. A number of modalities can be used in clinical practice and/or research to capture various dimensions of pain. Selection of a pain-assessment tool should be directed by the purpose of the assessment. Pain-assessment tools, many of which are currently in the early stages of validation, are discussed here. Development and validation of these multimodal tools is crucial for developing improved understanding of SCD pain and its management.