Sickle cell pain: a critical reappraisal

Preemptive Genotyping of CYP2C8 and CYP2C9 Allelic Variants Involved in NSAIDs Metabolism for Sickle Cell Disease Pain Management

Interindividual variability in analgesic effects of nonsteroidal anti-inflammatory drugs prescribed for sickle cell disease (SCD) pain is attributed to polymorphisms in the CYP2C8 and CYP2C9 enzymes. We described CYP2C8 and CYP2C9 genotype/phenotype profiles and frequency of emergency department (ED) visits for pain management in an African American SCD patient cohort. DNA from 165 unrelated patients was genotyped for seven CYP2C8 and 15 CYP2C9 alleles using the iPLEX ADME PGx multiplexed panel. CYP2C8*1 (0.806),*2 (0.164), *3 (0.018), and *4 (0.012) alleles were identified. Genotype frequencies were distributed as homozygous wild type (66.7%), heterozygous (27.8%), and homozygous variant/compound heterozygous (5.4%), respectively. CYP2C9*1 (0.824), *2 (0.027), *3 (0.012), *5 (0.009), *6 (0.009), *8 (0.042), *9 (0.061), and *11(0.015) were observed with extensive (68.5%), intermediate (18.1%) and poor predicted metabolizers (0.6%), respectively. Fifty-two and 55 subjects, respectively had at least one variant CYP2C8 or CYP2C9 allele. Although the distribution of the CYP2C9 (p = 0.0515) phenotypes was marginally significantly in high and low ED users; some CYP2C8 and CYP2C9 allelic combinations observed in 15.2% (25) of the cohort are associated with higher risks for analgesic failure. CYP2C8 and CYP2C9 preemptive genotyping could potentially enable clinicians to identify patients with impaired metabolic phenotypes.

Dexmedetomidine as an Adjuvant to Analgesic Strategy During Vaso-Occlusive Episodes in Adolescents with Sickle-Cell Disease

Patients with sickle-cell disease (SCD) can experience recurrent vaso-occlusive episodes (VOEs), which are associated with severe pain. While opioids are the mainstay of analgesic therapy, in some patients with SCD, increasing opioid use is associated with continued and increasing pain. Dexmedetomidine, an α2 -adrenoreceptor agonist with sedative and analgesic properties, has been increasingly used in the perioperative and intensive care settings and has been shown to reduce opioid requirement and to facilitate opioid weaning. Therefore, there might be a role for dexmedetomidine in pain management during VOEs in patients with SCD. Here, we present the hospital course of 3 patients who during the course of VOEs had severe pain unresponsive to opioids and ketamine and were treated with dexmedetomidine. Dexmedetomidine infusions that lasted for 3 to 6 days were associated with marked reduction in daily oral morphine-equivalent intake and decreases in pain scores (numeric rating scale). There were no hemodynamic changes that required treatment with vasoactive or anticholinergic agents. These preliminary findings of possible beneficial effects of dexmedetomidine in decreasing opioid requirements support the hypothesis that dexmedetomidine may have a role as a possible analgesic adjuvant to mitigate VOE-associated pain in patients with SCD.

Dopamine D3 receptor Ser9Gly and catechol-o-methyltransferase Val158Met polymorphisms and acute pain in sickle cell disease

BACKGROUND

Pain in sickle cell disease (SCD) is characterized by episodes of acute pain, primarily responsible for acute health care utilization, and persistent chronic pain. Pain severity and frequency vary significantly among patients with SCD. In this study, we investigated the possible contribution of monoamine gene polymorphisms to pain variation.

METHODS

Adult subjects with SCD completed PAINReportIt, a computerized McGill Pain Questionnaire, from which we calculated the Composite Pain Index. Utilization data were obtained from the medical record and biweekly telephone calls for 12 months. Utilization is defined as admissions to the emergency department and/or the acute care center resulting from a sickle cell pain crisis. We performed genotyping for catechol-O-methyltransferase (COMT) Val158Met (rs4680) and dopamine D3 receptor (DRD3) Ser9Gly (rs6280) polymorphisms, which were analyzed for associations with pain phenotypes.

RESULTS

Binary logistic models revealed that DRD3 Ser9Gly heterozygote patients were more likely not to have an acute pain crisis (odds ratio [OR] [95% confidence interval {CI}], 4.37 [1.39-22.89]; P = 0.020), which remained so when demographic variables were considered (OR [95% CI], 4.53 [1.41-28.58]; P = 0.016). COMT Val158Met Met allele showed lower probability for zero utilization (OR [95% CI], 0.32 [0.12-0.83]; P = 0.020) than the Val allele. In the negative binomial regression analysis, subjects with COMT Met/Met genotype had utilization incident rate ratio (95% CI) of 2.20 (1.21-3.99) over those with Val/Val (P = 0.010).

CONCLUSIONS

These exploratory findings suggest that DRD3 Ser9Gly and COMT Val158Met may contribute to pain heterogeneity in SCD, as suggested by the different rates of acute pain crisis. Specifically, SCD patients with the DRD3 homozygote genotypes, COMT 158 Met allele or Met/Met genotype, are more likely to have acute care utilization, an indicator of acute pain. These results, however, will need to be further examined in future large prospective studies.

A Mixed-Methods Study of Pain-related Quality of Life in Sickle Cell Vaso-Occlusive Crises

The quality of care for sickle cell disease patients hospitalized with a vaso-occlusive crisis (VOC) is poor, resulting in staggeringly high healthcare resource utilization. To evaluate in-patient care for VOC, we conducted a mixed-methods study of all adult sickle cell disease patients admitted with a VOC from 2010-2012. We quantitatively assessed the quality of care for all patients, and qualitatively studied a subset of frequently admitted patients. In total, there were 182 admissions from 57 unique patients. The median length of stay was 6 days and the 30-day readmission rate was 34.0%. We identified red blood cell transfusion and patient controlled analgesia use as predictors of increased length of stay. Interestingly, unlike prior findings, younger patients (18-30 years old) did not have increased healthcare resource utilization. Moreover, older age appeared to increase readmission rate and enhance the effect of patient controlled analgesia use on length of stay. Interviews of high healthcare resource utilizers revealed significant deficiencies in pain management and a strong desire for individualized care. This is the first study to examine in-patient predictors of acute healthcare resource utilization in sickle cell disease patients and to correlate them with qualitative perspectives of high healthcare resource utilizers.

Family caregiving for adults with sickle cell disease and extremely high hospital use

This study investigated coping with chronic illness in the adult patient-caregiver relationship for sickle cell disease, marked by debilitating acute and chronic pain. One-on-one interviews (N = 16) were conducted with eight primary caregivers of eight adults with extremely high hospital use, severe sickle cell disease with hospital admissions several times monthly over successive years. Caregivers were predominantly parents; two were romantic partners. Caregivers attributed disruptions to the disease's variability, tensions in how much support to give, and adults' inability to fulfill parental obligations. Both groups expressed fears of patients' increasing age, declining health, and early death. Targeted counseling and resilience training is recommended.

Fentanyl Buccal Tablet: A New Breakthrough Pain Medication in Early Management of Severe Vaso-Occlusive Crisis in Sickle Cell Disease

BACKGROUND

Sickle cell disease (SCD) is a worldwide distributed hereditary red cell disorder. The principal clinical manifestations of SCD are the chronic hemolytic anemia and the acute vaso-occlusive crisis (VOCs), which are mainly characterized by ischemic/reperfusion tissue injury. Pain is the main symptom of VOCs, and its management is still a challenge for hematologists, requiring a multidisciplinary approach.

METHODS

We carried out a crossover study on adult SCD patients, who received two different types of multimodal analgesia during two separate severe VOCs with time interval between VOCs of at least 6 months. The first VOC episode was treated with ketorolac (0.86 mg/kg/day) and tramadol (7.2 mg/kg/day) (TK treatment). In the second VOC episode, fentanyl buccal tablet (FBT; 100 μg) was introduced in a single dose after three hours from the beginning of TK analgesia (TKF treatment). We focused on the first 24 hours of acute pain management. The primary efficacy measure was the time-weighted-sum of pain intensity differences (SPID24). The secondary efficacy measures included the pain intensity difference (PID), the total pain relief (TOTPAR), and the time-wighted sum of anxiety (SAID24).

RESULTS

SPID24 was significantly higher in TKF than in TK treatment. All the secondary measures were significantly ameliorated in TKF compared to TK treatment, without major opioid side effects. Patients satisfaction was higher with TKF treatment than with TK one.

CONCLUSIONS

We propose that VOCs might require breakthrough pain drug strategy as vaso-occlusive phenomena and enhanced vasoconstriction promoting acute ischemic pain component exacerbate the continuous pain of VOCs. FBT might be a powerful and feasible tool in early management of acute pain during VOCs in emergency departments.

Psychological therapies for sickle cell disease and pain

BACKGROUND

Sickle cell disease comprises a group of genetic blood disorders. It occurs when the sickle haemoglobin gene is inherited from both parents. The effects of the condition are: varying degrees of anaemia which, if severe, can reduce mobility; a tendency for small blood capillaries to become blocked causing pain in muscle and bone commonly known as 'crises'; damage to major organs such as the spleen, liver, kidneys, and lungs; and increased vulnerability to severe infections. There are both medical and non-medical complications, and treatment is usually symptomatic and palliative in nature. Psychological interventions for individuals with sickle cell disease might complement current medical treatment, and studies of their efficacy have yielded encouraging results. This is an update of a previously published Cochrane Review.

OBJECTIVES

To examine the evidence that psychological interventions improve the ability of people with sickle cell disease to cope with their condition.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Haemoglobinopathies Trials Register, which comprises references identified from comprehensive electronic database searches and the Internet, handsearches of relevant journals and abstract books of conference proceedings.Date of the most recent search of the Group's Haemoglobinopathies Trials Register: 17 February 2015.

SELECTION CRITERIA

All randomised or quasi-randomised controlled trials comparing psychological interventions with no (psychological) intervention in people with sickle cell disease.

DATA COLLECTION AND ANALYSIS

Both authors independently extracted data and assessed the risk of bias of the included studies.

MAIN RESULTS

Twelve studies were identified in the searches and seven of these were eligible for inclusion in the review. Five studies, involving 260 participants, provided data for analysis. One study showed that cognitive behaviour therapy significantly reduced the affective component of pain (feelings about pain), mean difference -0.99 (95% confidence interval -1.62 to -0.36), but not the sensory component (pain intensity), mean difference 0.00 (95% confidence interval -9.39 to 9.39). One study of family psycho-education was not associated with a reduction in depression. Another study evaluating cognitive behavioural therapy had inconclusive results for the assessment of coping strategies, and showed no difference between groups assessed on health service utilisation. In addition, family home-based cognitive behavioural therapy did not show any difference compared to disease education. One study of patient education on health beliefs showed a significant improvement in attitudes towards health workers, mean difference -4.39 (95% CI -6.45 to -2.33) and medication, mean difference -1.74 (95% CI -2.98 to -0.50). Nonetheless, these results may not apply across all ages, severity of sickle cell disease, types of pain (acute or chronic), or setting.

AUTHORS' CONCLUSIONS

Evidence for the efficacy of psychological therapies in sickle cell disease is currently limited. This systematic review has clearly identified the need for well-designed, adequately-powered, multicentre randomised controlled trials assessing the effectiveness of specific interventions in sickle cell disease.

Sensory and Thermal Quantitative Testing in Children With Sickle Cell Disease

Very little is known about pain processing in sickle cell disease (SCD). We examined the mechanical and thermal sensory patterns in children with SCD. Children ages 10 to 17 years (n = 48; mean 13.7 ± 2.0 y; 22 females) participated in quantitative sensory testing (QST) procedures and completed a quality of life (PedsQL) and anxiety and depression scale (RCADS). Thirteen children showed evidence of abnormal pain processing, indicated by decreased sensitivity to heat or cold sensations (hypoesthesia), and pain experienced with nonpainful stimuli (allodynia). Pain ratings associated with cold and warm sensations were significantly higher in the subgroup with abnormal QST compared with the 35 SCD children with normal QST (P = 0.01 and P < 0.0001, respectively). The presence of hypoesthesia and allodynia in children with SCD may represent abnormal changes in the peripheral and central nervous system. Clinicians need to be aware that sickle cell pain may not only be inflammatory or ischemic secondary to vasoocclusion and hypoxia, but may also be neuropathic secondary to nerve injury or nerve dysfunction. Neuropathic pain in SCD may be the result of tissue damage after vaso-occlusion in neural tissues, whether peripherally or centrally. Future studies are needed to determine the presence of neuropathic pain in children with SCD.

Sickle cell disease patients with and without extremely high hospital use: pain, opioids, and coping

CONTEXT

Patients with sickle cell disease (SCD) and extremely high hospital use (EHHU) encounter significant challenges in pain management because of opioid medication use for pain and providers' concerns about addiction.

OBJECTIVES

To characterize engagement with the health care system surrounding opioid pain management among SCD patients with EHHU by comparing their experiences with low-hospital-using (LHU) patients and their medical providers' perspectives.

METHODS

One-on-one, semistructured qualitative interviews with patients and medical providers were audiotaped and transcribed. Participants were eight SCD patients with EHHU; matched by age, gender, and hemoglobinopathy type with eight SCD patients with low hospital use; and five providers identified by patients with EHHU as important to their care. A multidisciplinary team conducted chart review, created narrative summaries from the interviews, and used qualitative software to code transcripts based on themes.

RESULTS

High-hospital-using patients and LHU patients had similar descriptions of their experience of pain and pain management with opioids. Patients and medical providers shared concerns about addiction. LHU patients described themselves as allies using specific interpersonal and symptom-related strategies, whereas high-hospital-using patients took a defensive and reactive stance toward their providers, who were similarly defensive about their care.

CONCLUSION

The prescription of opioid medications for SCD pain management exacerbates issues of distrust in the patient-provider relationship. Such issues dominate patient care in patients with EHHU. Patients with EHHU and providers may learn from the proactive nature of LHU patients' engagement with the health care system as further research and interventions are designed for EHHU.

Multicenter COMPACT study of COMplications in patients with sickle cell disease and utilization of iron chelation therapy

BACKGROUND

Over the past few decades, lifespans of sickle cell disease (SCD) patients have increased; hence, they encounter multiple complications. Early detection, appropriate comprehensive care, and treatment may prevent or delay onset of complications.

OBJECTIVE

We collected longitudinal data on sickle cell disease (SCD) complication rates and associated resource utilization relative to blood transfusion patterns and iron chelation therapy (ICT) use in patients aged ≥16 years to address a gap in the literature.

RESEARCH DESIGN AND METHODS

Medical records of 254 SCD patients ≥16 years were retrospectively reviewed at three US tertiary care centers.

MAIN OUTCOME MEASURES

We classified patients into cohorts based on cumulative units of blood transfused and ICT history: <15 units, no ICT (Cohort 1 [C1]), ≥15 units, no ICT (Cohort 2 [C2]), and ≥15 units with ICT (Cohort 3 [C3]). We report SCD complication rates per patient per year; cohort comparisons use rate ratios (RRs).

RESULTS

Cohorts had 69 (C1), 91 (C2), and 94 (C3) patients. Pain led to most hospitalizations (76%) and emergency department (ED) (82%) visits. Among transfused patients (C2+C3), those receiving ICT were less likely to experience SCD complications than those who did not (RR [95% CI] C2 vs. C3: 1.33 [1.25-1.42]). Similar trends (RR [95% CI]) were observed in ED visits and hospitalizations associated with SCD complications (C2 vs. C3, ED: 1.94 [1.70-2.21]; hospitalizations: 1.61 [1.45-1.78]), but not in outpatient visits.

CONCLUSIONS

Although the most commonly reported SCD complication among all patients was pain, patients who received ICT were less likely to experience pain and other complications than those who did not. These results highlight the need for increased patient and provider education on the importance of comprehensive disease management.

Peripheral nerve injury induces persistent vascular dysfunction and endoneurial hypoxia, contributing to the genesis of neuropathic pain

Nerve injury is associated with microvascular disturbance; however, the role of the vascular system has not been well characterized in the context of neuropathic pain. Furthermore, ischemia is thought to play a role in a number of neuropathic pain conditions, and yet the role of hypoxia has also not been characterized in neuropathic pain conditions. In this study, we observed the presence of persistent endoneurial hypoxia in a mouse model of traumatic peripheral nerve injury, causing painful mononeuropathy. We attribute the ongoing hypoxia to microvascular dysfunction, endoneurial fibrosis, and increased metabolic requirements within the injured nerve. Increased lactate levels were observed in injured nerves, as well as increased oxygen consumption and extracellular acidification rates, suggesting that anaerobic glycolysis is required to maintain cellular ATP levels. Hypoxia causes a reduction in levels of the Na(+)/K(+) ATPase ion transporter in both cultured primary dorsal root ganglion neurons and injured peripheral nerve. A reduction of Na(+)/K(+) ATPase ion transporter levels likely contributes to the hyperexcitability of injured nerves. Physiological antagonism of hypoxia with hyperbaric oxygen alleviated mechanical allodynia in nerve-injured animals. These results suggest that hypoxia and the Na(+)/K(+) ATPase ion transporter may be a novel mechanistic target for the treatment of neuropathic pain. In addition, the findings support the possibility of using hypoxia activated pro-drugs to localize treatments for neuropathic pain and nerve injury to injured nerves.

Dexmedetomidine ameliorates nocifensive behavior in humanized sickle cell mice

Patients with sickle cell disease (SCD) can have recurrent episodes of vaso-occlusive crises, which are associated with severe pain. While opioids are the mainstay of analgesic therapy, in some patients, increasing opioid use results in continued and increasing pain. Many believe that this phenomenon results from opioid-induced tolerance or hyperalgesia or that SCD pain involves non-opioid-responsive mechanisms. Dexmedetomidine, a specific α2-adrenoreceptor agonist, which has sedative and analgesic properties, reduces opioid requirements, and can facilitate opioid withdrawal in clinical settings. We hypothesized that dexmedetomidine would ameliorate the nociception phenotype of SCD mice. Townes and BERK SCD mice, strains known to have altered nociception phenotypes, were used in a crossover preclinical trial that measured nocifensive behavior before and after treatment with dexmedetomidine or vehicle. In a linear dose-effect relationship, over 60-min, dexmedetomidine, compared with vehicle, significantly increased hot plate latency in Townes and BERK mice (P≤0.006). In sickle, but not control mice, dexmedetomidine improved grip force, an indicator of muscle pain (P=0.002). As expected, dexmedetomidine had a sedative effect in sickle and control mice as it decreased wakefulness scores compared with vehicle (all P<0.001). Interestingly, the effects of dexmedetomidine on hot plate latency and wakefulness scores were different in sickle and control mice, i.e., dexmedetomidine-related increases in hotplate latency and decreases in wakefulness scores were significantly smaller in Townes sickle compared to control mice. In conclusion, these findings of beneficial effects of dexmedetomidine on the nociception phenotype in SCD mice might support the conduct of studies of dexmedetomidine in SCD patients.

Low-molecular-weight heparins for managing vasoocclusive crises in people with sickle cell disease: a summary of a cochrane systematic review

We summarize a Cochrane systematic review that was conducted to assess the effects of low-molecular-weight heparins (LMWH) for managing vasoocclusive crises (VOC) in people with sickle cell disease. Sickle cell disease is one of the most common and severe genetic disorders in the world. It can be divided into three broadly distinct clinical phenotypes characterized by either hemolysis, pain syndromes or organ damage. Pain is the most prominent symptom of vasoocclusion, and hypercoagulability is a well-established pathogenic phenomenon in people with sickle cell disease. Searches included the Cochrane Cystic Fibrosis and Genetic Disorders Group Haemoglobinopathies Trials Register, abstract books of conference proceedings and several online trials registries (December 2012). One study (with an overall unclear to high risk of bias) comprising 253 participants was included. This study provided limited data, but concluded that tinzaparin resulted in a more rapid resolution of pain, and in a statistically significant lower number of hospitalization days compared to a placebo. Two minor bleeding events were reported as adverse events in the tinzaparin group. Based on the results from this single study, there is incomplete evidence to either support or refute the effectiveness of LMWH in people with sickle cell disease.

Platelet-neutrophil interactions under thromboinflammatory conditions

Platelets primarily mediate hemostasis and thrombosis, whereas leukocytes are responsible for immune responses. Since platelets interact with leukocytes at the site of vascular injury, thrombosis and vascular inflammation are closely intertwined and occur consecutively. Recent studies using real-time imaging technology demonstrated that platelet-neutrophil interactions on the activated endothelium are an important determinant of microvascular occlusion during thromboinflammatory disease in which inflammation is coupled to thrombosis. Although the major receptors and counter receptors have been identified, it remains poorly understood how heterotypic platelet-neutrophil interactions are regulated under disease conditions. This review discusses our current understanding of the regulatory mechanisms of platelet-neutrophil interactions in thromboinflammatory disease.

Kinetics of sickle cell biorheology and implications for painful vasoocclusive crisis

We developed a microfluidics-based model to quantify cell-level processes modulating the pathophysiology of sickle cell disease (SCD). This in vitro model enabled quantitative investigations of the kinetics of cell sickling, unsickling, and cell rheology. We created short-term and long-term hypoxic conditions to simulate normal and retarded transit scenarios in microvasculature. Using blood samples from 25 SCD patients with sickle hemoglobin (HbS) levels varying from 64 to 90.1%, we investigated how cell biophysical alterations during blood flow correlated with hematological parameters, HbS level, and hydroxyurea (HU) therapy. From these measurements, we identified two severe cases of SCD that were also independently validated as severe from a genotype-based disease severity classification. These results point to the potential of this method as a diagnostic indicator of disease severity. In addition, we investigated the role of cell density in the kinetics of cell sickling. We observed an effect of HU therapy mainly in relatively dense cell populations, and that the sickled fraction increased with cell density. These results lend support to the possibility that the microfluidic platform developed here offers a unique and quantitative approach to assess the kinetic, rheological, and hematological factors involved in vasoocclusive events associated with SCD and to develop alternative diagnostic tools for disease severity to supplement other methods. Such insights may also lead to a better understanding of the pathogenic basis and mechanism of drug response in SCD.

Iron, inflammation, and early death in adults with sickle cell disease

RATIONALE

Patients with sickle cell disease (SCD) have markers of chronic inflammation, but the mechanism of inflammation and its relevance to patient survival are unknown.

OBJECTIVE

To assess the relationship between iron, inflammation, and early death in SCD.

METHODS AND RESULTS

Using peripheral blood mononuclear cell transcriptome profile hierarchical clustering, we classified 24 patients and 10 controls in clusters with significantly different expression of genes known to be regulated by iron. Subsequent gene set enrichment analysis showed that many genes associated with the high iron cluster were involved in the toll-like receptor system (TLR4, TLR7, and TLR8) and inflammasome complex pathway (NLRP3, NLRC4, and CASP1). Quantitative PCR confirmed this classification and showed that ferritin light chain, TLR4, and interleukin-6 expression were >100-fold higher in patients than in controls (P<0.001). Further linking intracellular iron and inflammation, 14 SCD patients with a ferroportin Q248H variant that causes intracellular iron accumulation had significantly higher levels of interleukin-6 and C-reactive protein compared with 14 matched SCD patients with the wild-type allele (P<0.05). Finally, in a cohort of 412 patients followed for a median period of 47 months (interquartile range, 24-82), C-reactive protein was strongly and independently associated with early death (hazard ratio, 3.0; 95% confidence interval, 1.7-5.2; P<0.001).

CONCLUSIONS

Gene expression markers of high intracellular iron in patients with SCD are associated with markers of inflammation and mortality. The results support a model in which intracellular iron promotes inflammatory pathways, such as the TLR system and the inflammasome, identifying important new pathways for additional investigation.

Safety and Utility of Quantitative Sensory Testing among Adults with Sickle Cell Disease: Indicators of Neuropathic Pain?

OBJECTIVES

Pain is the hallmark symptom of sickle cell disease (SCD), yet the types of pain that these patients experience, and the underlying mechanisms, have not been well characterized. The study purpose was to determine the safety and utility of a mechanical and thermal quantitative sensory testing (QST) protocol and the feasibility of utilizing neuropathic pain questionnaires among adults with SCD.

METHODS

A convenience sample (N = 25, 18 women, mean age 38.5 ± 12.5 [20-58 years]) completed self-report pain and quality-of-life tools. Subjects also underwent testing with the TSA-II NeuroSensory Analyzer and calibrated von Frey microfilaments.

RESULTS

We found that the QST protocol was safe and did not stimulate a SCD pain crisis. There was evidence of central sensitization (n = 15), peripheral sensitization (n = 1), a mix of central and peripheral sensitization (n = 8), or no sensitization (n = 1). The neuropathic pain self-report tools were feasible with evidence of construct validity; 40% of the subjects reported S-LANSS scores that were indicative of neuropathic pain and had evidence of central, peripheral or mixed sensitization.

DISCUSSION

The QST protocol can be safely conducted in adults with SCD and provides evidence of central or peripheral sensitization, which is consistent with a neuropathic component to SCD pain. These findings are novel, warrant a larger confirmatory study, and indicate the need for normative QST data from African American adults and older adults.

Morphine for the treatment of pain in sickle cell disease

Pain is a hallmark of sickle cell disease (SCD) and its treatment remains challenging. Opioids are the major family of analgesics that are commonly used for treating severe pain. However, these are not always effective and are associated with the liabilities of their own. The pharmacology and multiorgan side effects of opioids are rapidly emerging areas of investigation, but there remains a scarcity of clinical studies. Due to opioid-induced endothelial-, mast cell-, renal mesangial-, and epithelial-cell-specific effects and proinflammatory as well as growth influencing signaling, it is likely that when used for analgesia, opioids may have organ specific pathological effects. Experimental and clinical studies, even though extremely few, suggest that opioids may exacerbate existent organ damage and also stimulate pathologies of their own. Because of the recurrent and/or chronic use of large doses of opioids in SCD, it is critical to evaluate the role and contribution of opioids in many complications of SCD. The aim of this review is to initiate inquiry to develop strategies that may prevent the inadvertent effect of opioids on organ function in SCD, should it occur, without compromising analgesia.

Sickle cell disease: a neglected chronic disease of increasing global health importance

Sickle cell disease (SCD) is a single gene disorder causing a debilitating systemic syndrome characterised by chronic anaemia, acute painful episodes, organ infarction and chronic organ damage and by a significant reduction in life expectancy. The origin of SCD lies in the malarial regions of the tropics where carriers are protected against death from malaria and hence enjoy an evolutionary advantage. More recently, population migration has meant that SCD now has a worldwide distribution and that a substantial number of children are born with the condition in higher-income areas, including large parts of Europe and North and South America. Newborn screening, systematic clinical follow-up and prevention of sepsis and organ damage have led to an increased life expectancy among people with SCD in many such countries; however, in resource-limited settings where the majority continue to be born, most affected children continue to die in early childhood, usually undiagnosed, due to the lack of effective programmes for its early detection and treatment. As new therapies emerge, potentially leading to disease amelioration or cure, it is of paramount importance that the significant burden of SCD in resource-poor countries is properly recognised.

Perception of pain among pediatric patients with sickle cell pain crisis

Pain related to vasoocclusion is the most common reason for emergency department visits and hospital stays among pediatric patients with sickle cell disease. Using a prospective descriptive design, patients hospitalized with sickle cell pain were asked to complete the Adolescent Pediatric Pain Tool on each day of their hospital stay, providing data on the location, intensity, and quality of their pain. Data for 82 hospital stays were collected from 40 African American study participants. Mean age was 14.8 years, and mean length of stay (LOS) was 5.1 days. Mean LOS for 8 to 12 year olds (3.23 days; n = 22) was shorter than mean LOS for 13 to 19 year olds (5.85 days; n = 60). This LOS difference was significant (P = .004). Difference in LOS by gender was not significant. Higher initial number of body sites with pain was significantly associated with longer LOS (r = .39; P < .001). Higher initial pain intensity scores were significantly associated with longer LOS (r = .37; P = .001). Higher initial number of word descriptors was only weakly associated with longer LOS. Neither gender nor age differences were significant for Adolescent Pediatric Pain Tool data.

Ischemia-reperfusion injury in sickle cell anemia: relationship to acute chest syndrome, endothelial dysfunction, arterial vasculopathy, and inflammatory pain

Ischemia-reperfusion (I/R) physiology, also called reperfusion injury, instigates vascular and tissue injury in human disease states. This review describes why sickle cell anemia should be conceptualized in this fashion and how I/R physiology explains the genesis of characteristic aspects of vascular pathobiology and clinical disease in sickle cell anemia. The nature of I/R and its relevance to sickle cell anemia are discussed, with an emphasis on the acute chest syndrome, endothelial dysfunction with aberrant vasoregulation, circle of Willis vasculopathy, and inflammatory pain. Viewing sickle disease from this perspective elucidates defining pathophysiology and identifies a host of novel potential therapeutic targets.

Challenges and resilience in the lives of adults with sickle cell disease

This qualitative study focused on the experiences of adults living with sickle cell disease (SCD) in the New York City area. Twenty-three individuals participated in one of three focus groups. The purpose of this study was to learn if appropriate health care for individuals with sickle cell disease, based on years of research, has been implemented. The findings indicate that best practices in the treatment of SCD are often not followed by medical personnel. Critical race theory provides a framework to understand the 10 emergent themes. The participants' responses illustrate resilience in facing adversity. Implications for social work practice are presented.

Pathophysiology and principles of management of the many faces of the acute vaso-occlusive crisis in patients with sickle cell disease

Effective management of sickle cell pain entails a thorough understanding of its pathophysiology and the pharmacogenomics of the opioids used to manage it. In recent years, there has been significant progress along these two lines. At the pathophysiologic level, there is evidence that the severity and frequency of painful stimuli modulate their transmission at the level of the dorsal horn of the spinal cord. This modulation is achieved via two channels: the α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and NMDA receptors. Initially, the AMPA channel controls the transmission of stimuli of mild-moderate severity. Once the AMPA channel reaches its limit of membrane depolarization, the NMDA channel is activated and facilitates the transmission of painful stimuli in a progressive fashion leading to central sensitization and glial activation. At the level of pharmacogenomics, the metabolism of each opioid is patient-specific. Glucuronidation is unique for the metabolism of morphine, hydromorphone, and oxymorphone. The metabolism of all other opioids requires specific Cytochrome P450 (CYP) isoenzymes. The activity of each isoenzyme and the activity of the metabolites of each opioid vary among patients depending on their genetic makeup and coexistent environmental factors such as the use of other medications that may enhance or inhibit the CYP isoenzyme activity.

MEK inhibitors, novel anti-adhesive molecules, reduce sickle red blood cell adhesion in vitro and in vivo, and vasoocclusion in vivo

In sickle cell disease, sickle erythrocyte (SSRBC) interacts with endothelial cells, leukocytes, and platelets, and activates coagulation and inflammation, promoting vessel obstruction, which leads to serious life-threatening complications, including acute painful crises and irreversible damage to multiple organs. The mitogen-activated protein kinase, ERK1/2, is abnormally activated in SSRBCs. However, the therapeutic potential of SSRBC ERK1/2 inactivation has never been investigated. I tested four different inhibitors of MEK1/2 (MEK), the kinase that activates ERK1/2, in a model of human SSRBC adhesion to TNFα-activated endothelial cells (ECs). SSRBC MEK inhibition abrogated adhesion to non-activated and TNFα-activated ECs to levels below baseline SSRBC adhesion to non-activated ECs in vitro. SSRBC MEK inhibition also prevented SSRBCs from activating naïve neutrophils to adhere to endothelium. To determine the effect of MEK inhibitors on SSRBC adherence in vivo, sham-treated or MEK inhibitor-treated SSRBCs were infused to nude mice previously treated with TNFα. Sham-treated SSRBCs displayed marked adhesion and occlusion of enflamed vessels, both small and large. However, SSRBC treatment with MEK inhibitors ex vivo showed poor SSRBC adhesion to enflamed vessels with no visible vasoocclusion in vivo. In addition, MEK inhibitor treatment of SSRBCs reduced SSRBC organ trapping and increased the number of SSRBCs circulating in bloodstream. Thus, these data suggest that SSRBC ERK1/2 plays potentially a critical role in sickle pathogenesis, and that MEK inhibitors may represent a valuable intervention for acute sickle cell crises.

Improving outcomes in children with sickle cell disease: treatment considerations and strategies

Over the past decades there has been a significant improvement in the care of patients with sickle cell disease (SCD) in high-income countries. However, more needs to be learned about the complex pathophysiology and the factors that contribute to the development of end organ damage from the disease. While antibiotic prophylaxis and appropriate treatment of infections have resulted in a significant reduction of early mortality, management of the painful episodes and prevention of organ damage remain a challenge. Hydroxyurea is the only medication approved as disease-modifying therapy, and bone marrow transplant as curative treatment is not available to most patients. In low-income countries with the highest disease burden, early mortality is high due to limited resources for systematic screening, early diagnosis, and disease management. In order to improve outcomes in patients with SCD in high-income countries, better and widespread implementation of known disease-modifying therapies and the development of newer therapies targeting key pathophysiologic pathways are required. In low-income countries with high disease burden, innovative approaches to develop low-cost diagnostic devices and treatments that can be implemented to scale are needed to combat early mortality from the disease. Sustainable solutions in low-resource settings require evidence-based affordable interventions that can be integrated into primary and secondary healthcare systems.

Sickle cell disease in mice is associated with sensitization of sensory nerve fibers

The pain phenotype in sickle cell disease (SCD) patients is highly variable. A small percentage of SCD patients experience many vaso-occlusive crises/year, 5% of patients account for over 30% of pain episodes, while 39% report few episodes of severe pain. Clearly, a better understanding of the pathobiology of SCD is needed to improve its therapy. Humanized sickle cell mice recapitulate several phenotypes of SCD patients and provide a model for the study of SCD pain. Researchers have shown that one strain of humanized SCD mice, the BERK strain, has abnormal pain phenotype. However, the nociception phenotype of another humanized SCD mouse strain, the Townes strain, has not been described. In a large cross-sectional study of BERK and Townes SCD mice, we examined thermosensory response and sensory nerve fiber function using sine-wave electrical stimulation at 2000, 250, and 5 Hz to stimulate preferentially Aβ, Aδ, and C sensory nerve fibers, respectively. We found that BERK and Townes mice, compared to respective controls, had decreases in 2000, 250, and 5 Hz current vocalization thresholds in patterns that suggest sensitization of a broad spectrum of sensory nerve fibers. In addition, the pattern of sensitization of sensory fibers varied according to strain, sex, age, and mouse genotype. In a similarly variable pattern, Townes and BERKs also had significantly altered sensitivity to noxious thermal stimuli in agreement with what has been shown by others. In summary, the analysis of somatosensory function using sine-wave electrical stimulation in humanized sickle cell mice suggests that in SCD, both myelinated and unmyelinated, fibers are sensitized. The pattern of sensory fiber sensitization is distinct from that observed in pain models of neuropathic and inflammatory pain. These findings raise the possibility that sensitization of a broad spectrum of sensory fibers might contribute to the altered and variable nociception phenotype in SCD.

Quantitative intravital two-photon excitation microscopy reveals absence of pulmonary vaso-occlusion in unchallenged Sickle Cell Disease mice

Sickle cell disease (SCD) is a genetic disorder that leads to red blood cell (RBC) sickling, hemolysis and the upregulation of adhesion molecules on sickle RBCs. Chronic hemolysis in SCD results in a hyper-inflammatory state characterized by activation of circulating leukocytes, platelets and endothelial cells even in the absence of a crisis. A crisis in SCD is often triggered by an inflammatory stimulus and can lead to the acute chest syndrome (ACS), which is a type of lung injury and a leading cause of mortality among SCD patients. Although it is believed that pulmonary vaso-occlusion could be the phenomenon contributing to the development of ACS, the role of vaso-occlusion in ACS remains elusive. Intravital imaging of the cremaster microcirculation in SCD mice has been instrumental in establishing the role of neutrophil-RBC-endothelium interactions in systemic vaso-occlusion; however, such studies, although warranted, have never been done in the pulmonary microcirculation of SCD mice. Here, we show that two-photon excitation fluorescence microscopy can be used to perform quantitative analysis of neutrophil and RBC trafficking in the pulmonary microcirculation of SCD mice. We provide the experimental approach that enables microscopic observations under physiological conditions and use it to show that RBC and neutrophil trafficking is comparable in SCD and control mice in the absence of an inflammatory stimulus. The intravital imaging scheme proposed in this study can be useful in elucidating the cellular and molecular mechanism of pulmonary vaso-occlusion in SCD mice following an inflammatory stimulus.

Development of interactive algorithm for clinical management of acute events related to sickle cell disease in emergency department

Sickle cell disease (SCD ORPHA232; OMIM 603903) is a rare hereditary red cell disorder, which global distribution is changed in the last decade due to immigration-fluxes from endemic areas to Western-countries. One of the main clinical manifestations of SCD are the acute painful vaso-occlusive crisis, which cause frequent accesses of SCD patients to the emergency departments (EDs). This has generated the requirement of feasible tools for emergency givers. In the context of the scientific-Italian-Society for the study of Thalassemias and Hemoglobinopathies (SITE), we developed an algorithm with interactive windows to guide physicians in managing SCD patients in EDs.

Management of the acute painful crisis in sickle cell disease- a re-evaluation of the use of opioids in adult patients

Management of the acute painful crisis (APC) of sickle cell disease (SCD) remains unsatisfactory despite advances in the understanding and management of acute pain in other clinical settings. One reason for this is an unsophisticated approach to the use of opioid analgesics for pain management. This applies to haematologists who are responsible for developing acute sickle pain management protocols for their patients, and to health care staff in the acute care setting. The objective of this article is to evaluate the evidence for use of opioids in APC management. We have highlighted the possibilities for improving management by using alternatives to morphine, and intranasal (IN) or transmucosal routes of administration for rapid onset of analgesia in the emergency department (ED). We suggest how experience gained in managing acute sickle pain in children could be extrapolated to adolescents and young adults. We have also questioned whether patients given strong opioids in the acute setting are being safely monitored and what resources are required to ensure efficacy, safety and patient satisfaction. We also identify aspects of care where there are significant differences of opinion, which require further study by randomized controlled trial.

Hospitalist management of vaso-occlusive pain crisis in patients with sickle cell disease using a pathway of care

BACKGROUND

Patients with sickle cell disease (SCD) suffer from intermittent vaso-occlusive pain crises (VOCs). These crises lead to frequent hospitalizations, significant morbidity, and increased mortality risk. Care pathways can enhance efficiency and quality of care. Our study sought to evaluate the development and implementation of a care pathway for patients with SCD experiencing VOCs.

METHODS

The University of North Carolina (UNC) Comprehensive Sickle Cell Program provides all levels of care for a large population of patients with sickle cell anemia. All patients admitted to UNC Hospitals with SCD VOCs from January 2009 through June 2011 were evaluated. During this time period, we also assessed sequential prospective cohorts during progressive phases of developing and implementing a quality improvement and pathway of care program for this patient population in our study. The developed pathway entailed geographic localization for VOC patients, a single group of faculty physicians caring for these patients, and early use of patient-controlled analgesia (PCA) to achieve pain control. Physicians from the UNC Hospital Medicine Program were responsible for the initiatives. Cohorts were compared to a baseline historical control. Outcomes of interest included patient length of stay (LOS) in the hospital, 30-day readmission rate, need for transfusion, incidence of acute chest syndrome, use of naloxone, and use of PCA.

RESULTS

Compared with an historical baseline cohort, the development and implementation of a VOC care pathway for patients with SCD led to reduction in average hospital LOS by 1.44 days (P < 0.05) and an increase in use of PCAs (P < 0.05). Patient readmission rates, number of transfusions, incidence of acute chest syndrome, and use of naloxone did not significantly change.

CONCLUSIONS

Hospitalist-led management of patients with SCD VOCs using a care pathway that emphasizes early, aggressive PCA-based pain control is associated with reduced hospital LOS. The LOS reduction seen in our study is clinically meaningful. Notably, other measures of patient outcomes and quality of care metrics did not change significantly, and some trended towards improvement.

Treatment of the acute sickle cell vaso-occlusive crisis in the Emergency Department: a Brazilian method of switching from intravenous to oral morphine

OBJECTIVES

Describe the treatment of patients with vaso-occlusive crises (VOC) in a Brazilian emergency department (ED) and the successful switch from intravenous to oral morphine.

PATIENTS AND METHODS

We analyzed records of 315 patients with sickle cell disease using two different protocols for pain: one in March 2010 prescribing intravenous morphine every 4 h throughout their stay, and another in March 2011 and 2012 prescribing one initial dose of intravenous morphine followed by equianalgesic doses of oral morphine every 4 h. Patients were triaged into three groups: mild, moderate, and severe VOC. The mild group was treated within 1 h after triage, the moderate within 30 min and the severe was treated immediately. Patients whose pain was not relieved within 6 h after the first dose of morphine were transferred into a different holding area of the ED where they continued to receive the same treatment for 48 h after which they were hospitalized if still in pain.

RESULTS

The number of patients who stayed <24 h in the ED increased significantly from 63 in 2010 to 87 in 2012, and the number of admissions decreased from 26 in 2010 to 10 in 2012. The incidence of acute chest syndrome decreased from 8.5% in 2010 to 1.9% in 2012.

CONCLUSION

Patients treated with oral morphine stayed a shorter time in the ED, had more pain relief, were admitted less frequently, and had less acute chest syndrome. These differences may be due to environmental, cultural, psychological, and pharmacogenetic factors.

The neurobiology of skeletal pain

Disorders of the skeleton are one of the most common causes of chronic pain and long-term physical disability in the world. Chronic skeletal pain is caused by a remarkably diverse group of conditions including trauma-induced fracture, osteoarthritis, osteoporosis, low back pain, orthopedic procedures, celiac disease, sickle cell disease and bone cancer. While these disorders are diverse, what they share in common is that when chronic skeletal pain occurs in these disorders, there are currently few therapies that can fully control the pain without significant unwanted side effects. In this review we focus on recent advances in our knowledge concerning the unique population of primary afferent sensory nerve fibers that innervate the skeleton, the nociceptive and neuropathic mechanisms that are involved in driving skeletal pain, and the neurochemical and structural changes that can occur in sensory and sympathetic nerve fibers and the CNS in chronic skeletal pain. We also discuss therapies targeting nerve growth factor or sclerostin for treating skeletal pain. These therapies have provided unique insight into the factors that drive skeletal pain and the structural decline that occurs in the aging skeleton. We conclude by discussing how these advances have changed our understanding and potentially the therapeutic options for treating and/or preventing chronic pain in the injured, diseased and aged skeleton.

Treating pain in sickle cell disease with opioids: clinical advances, ethical pitfalls

This article explores the ethical principles of prescribing in Sickle Cell Disease. The first two sections of the article provide detailed scientific justification for the last section of the manuscript, which explores and discusses the ethical principles.

Pain measurement as part of primary healthcare of adult patients with sickle cell disease

Objective

The aim of this exploratory, cross-sectional study was to evaluate pain in sickle cell disease patients and aspects related to primary healthcare.

Methods

Data were obtained through home interviews. The assessment instruments (body diagram, Numerical Pain Scale, McGill Pain Questionnaire) collected information on the underlying disease and on pain. Data were analyzed using the Statistical Package for Social Sciences program for Windows. Associations between the subgroups of sickle cell disease patients (hemoglobin SS, hemoglobin SC, sickle β-thalassemia and others) and pain were analyzed using contingency tables and non-parametric tests of association (classic chi-square, Fisher's and Kruskal-Wallis) with a level of 5% (p-value < 0.05) being set for the rejection of the null hypothesis.

Results

Forty-seven over 18-year-old patients with sickle cell disease were evaluated. Most were black (78.7%) and female (59.6%) and the mean age was 30.1 years. The average number of bouts of pain annually was 7.02; pain was predominantly reported by individuals with sickle cell anemia (hemoglobin SS). The intensity of pain (Numeric Pain Scale) was 5.5 and the quantitative index (McGill) was 35.9. This study also shows that patients presented a high frequency of moderately painful crises in their own homes.

Conclusion

According to these facts, it is essential that pain related to sickle cell disease is properly identified, quantified, characterized and treated at the three levels of healthcare. In primary healthcare, accurate measurement of pain combined with better care may decrease acute painful episodes and consequently minimize tissue damage, thus improving the patient's overall health.

Sickle cell disease related mortality in the United States (1999-2009)

BACKGROUND

Little is known about the national outcome of children and adults with sickle cell disease (SCD) given contemporary care.

PROCEDURE

We investigated the number of deaths, standardized crude and age-adjusted mortality rates, and causes of death among individuals with SCD across the United States during 1999-2009 according to death certificates by using a publicly available website (http://wonder.cdc.gov/). Data were compared to mortality during 1979-1998.

RESULTS

When compared to 1979-1998, mortality significantly decreased by 61% in infants <1 year of age, by 67% in children aged 1-4 years, and by 22-35% in children aged 5-19 years. After 19 years of age, mortality rates increased from 0.6 in the 15-19 year group to 1.4/100,000 in the 20-24 year group, corresponding to the transition period from pediatric to adult medical care, and this increase was similar during 1979-1998. Although the age groups with the highest mortality were 35-44 years for males and 45-54 years for females, there was a tendency for longer survival because there were more deaths among those individuals 55-74 years of age compared to previous years. For all individuals, the causes of deaths were cardiac disease (31.6%), respiratory (28.1%), renal (16.4%), infectious (14.4%), neurologic (11.9%), and gastrointestinal and hepatobiliary (9.2%) in nature. Cancer was the cause of death in <1%.

CONCLUSION

Mortality during childhood has decreased significantly. However, the transition period from pediatric to adult care is critical. Risk-reduction, monitoring, and early treatment intervention of cardiovascular disease in adults is warranted.

Morphine stimulates platelet-derived growth factor receptor-β signalling in mesangial cells in vitro and transgenic sickle mouse kidney in vivo

BACKGROUND

Pain and renal dysfunction occur in sickle cell disease. Morphine used to treat pain also co-activates platelet-derived growth factor receptor-β (PDGFR-β), which can adversely affect renal disease. We examined the influence of morphine in mesangial cells in vitro and in mouse kidneys in vivo.

METHODS

> Mouse mesangial cells treated with 1 μM morphine in vitro or kidneys of transgenic homozygous or hemizygous sickle or control mice (n=3 for each), treated with morphine (0.75, 1.4, 2.14, 2.8, 3.6, and 4.3 mg kg(-1) day(-1) in two divided doses during the first, second, third, fourth, fifth, and sixth weeks, respectively), were used. Western blotting, bromylated deoxy uridine incorporation-based cell proliferation assay, reverse transcriptase-polymerase chain reaction, immunofluorescent microscopy, and blood/urine chemistry were used to analyse signalling, cell proliferation, opioid receptor (OP) expression, and renal function.

RESULTS

Morphine stimulated phosphorylation of PDGFR-β and mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) to the same extent as induced by platelet-derived growth factor-BB (PDGF-BB) and promoted a two-fold increase in mesangial cell proliferation. The PDGFR-β inhibitor, AG1296, OP antagonists, and silencing of μ- and κ-OP abrogated morphine-induced MAPK/ERK phosphorylation and proliferation by ~100%. Morphine treatment of transgenic mice resulted in phosphorylation of PDGFR-β, MAPK/ERK, and signal transducer and activator of transcription 3 (Stat3) in the kidneys. Morphine inhibited micturition and blood urea nitrogen (BUN) clearance and increased BUN and urinary protein in sickle mice.

CONCLUSION

Morphine stimulates mitogenic signalling leading to mesangial cell proliferation and promotes renal dysfunction in sickle mice.

Mast cell activation contributes to sickle cell pathobiology and pain in mice

Sickle cell anemia (SCA) is an inherited disorder associated with severe lifelong pain and significant morbidity. The mechanisms of pain in SCA remain poorly understood. We show that mast cell activation/degranulation contributes to sickle pain pathophysiology by promoting neurogenic inflammation and nociceptor activation via the release of substance P in the skin and dorsal root ganglion. Mast cell inhibition with imatinib ameliorated cytokine release from skin biopsies and led to a correlative decrease in granulocyte-macrophage colony-stimulating factor and white blood cells in transgenic sickle mice. Targeting mast cells by genetic mutation or pharmacologic inhibition with imatinib ameliorates tonic hyperalgesia and prevents hypoxia/reoxygenation-induced hyperalgesia in sickle mice. Pretreatment with the mast cell stabilizer cromolyn sodium improved analgesia following low doses of morphine that were otherwise ineffective. Mast cell activation therefore underlies sickle pathophysiology leading to inflammation, vascular dysfunction, pain, and requirement for high doses of morphine. Pharmacological targeting of mast cells with imatinib may be a suitable approach to address pain and perhaps treat SCA.

Male gender, increased blood viscosity, body mass index and triglyceride levels are independently associated with systemic relative hypertension in sickle cell anemia

Patients with sickle cell anemia (SCA) have usually lower diastolic, systolic and mean blood pressure (BP) than the general population. However, BP values ≥120/70 mmHg considerably increase the risk for acute and chronic complications in SCA. The aim of this study was to identify biological factors associated with relative hypertension in adults with SCA. We compared the hematological, lipid and hemolytic profiles, as well as blood viscosity, between SCA patients with normal BP (<120/70 mmHg, n = 54) and those with relative hypertension (BP≥120/70 mmHg, n = 43). Our results demonstrated that male gender (OR: 3.49; 95%CI 1.20 to 10.16, p<0.05), triglycerides (OR: 9.19; 95% CI 2.29 to 36.95, p<0.01), blood viscosity (OR: 1.35; 95% CI 1.01 to 1.81, p<0.05) and body mass index (OR: 1.37; 95% CI 1.14 to 1.64, p<0.01) were independent risks factors for relative hypertension in SCA. No association was found between the BP status and the positive history of painful vaso-occlusive crisis or acute chest syndrome. An association between triglycerides level and the occurrence of these two major acute complications was detected. Our study suggests that male gender, increased triglycerides level, BMI and blood viscosity could increase the risk for developing relative hypertension in SCA. In addition, our results support a role of moderately elevated triglycerides in the pathophysiology of vaso-occlusive events.

Oral ketamine for sickle cell crisis pain refractory to opioids

There is literature demonstrating that the N-methyl-d-aspartate (NMDA) receptor antagonist ketamine has analgesic properties that can be used as an adjuvant to opiates for pain relief in multiple various conditions and pain states. However, there is a lack of published information on ketamine used in persons with sickle cell disease in acute pain crises. The Virginia Commonwealth University Palliative Care team was consulted on a 38-year-old African American female with sickle cell thalassemia in severe acute pain crisis overlying chronic pain related to her disease. Pain control was unable to be achieved with escalating doses of opiates and other adjuvant medications. The patient responded well to an intravenous test dose of ketamine and was subsequently placed on an oral regimen of ketamine in addition to opiates. In the 24-hour period following ketamine initiation, the patient's pain was able to be controlled on decreased amounts of opiates. She was eventually transitioned to an oral opiate and ketamine regimen, which allowed her to be discharged home with pain levels close to her baseline and the ability to function and perform all activities of daily living.

Nature and nurture of human pain

Humans are very different when it comes to pain. Some get painful piercings and tattoos; others can not stand even a flu shot. Interindividual variability is one of the main characteristics of human pain on every level including the processing of nociceptive impulses at the periphery, modification of pain signal in the central nervous system, perception of pain, and response to analgesic strategies. As for many other complex behaviors, the sources of this variability come from both nurture (environment) and nature (genes). Here, I will discuss how these factors contribute to human pain separately and via interplay and how epigenetic mechanisms add to the complexity of their effects.