The effect of sleep continuity on pain in adults with sickle cell disease

Knowledge and Experience of In-Home Virtual Reality for Chronic Pain in Sickle Cell Disease

Many adults with sickle cell disease experience chronic, nonvaso-occlusive pain that can benefit from nonpharmacological interventions available for use in the home setting. Virtual reality (VR) has been shown to be effective in decreasing pain in chronic pain conditions and may be useful for home-based self-management of chronic pain in sickle cell. However, the literature lacks studies examining this potential. Additionally, the knowledge and experiences of adults with sickle cell who have tried VR for home-based chronic pain management have not yet been reported. This qualitative, descriptive pilot study explored the knowledge and perceptions of VR among adults with sickle cell and their experience with using in-home VR for chronic pain. Nine participants completed demographic questionnaires and an individual interview that was recorded, transcribed verbatim, and analyzed using thematic analysis. Participants were 21 to 38 years of age, and most were female (88.9%) with a medium or high sickle cell disease severity (88.9%) and a chronic pain-grade classification of grade III (high disability-moderately limiting) or grade IV (high disability-severely limiting) (55.5%). Interview themes, which aligned with the technology acceptance model, were 1) pain beliefs and self-management, 2) VR as another world, and 3) experience of using in-home VR. Based on preliminary data, VR shows promise as a strategy for nonpharmacological management of chronic pain in adults with sickle cell. However, further investigations are warranted to mitigate the challenges and limitations associated with using VR in this capacity. PERSPECTIVE: Few evidence-based, nonpharmacological interventions exist for chronic pain in adults with sickle cell disease. This first qualitative, pilot study of in-home VR for chronic pain in adults with sickle cell disease suggests that VR interventions need further exploration as a nonpharmacological strategy for mitigating their pain in the home setting.

Exploring the role of viscosity-vaso-occlusion and haemolysis-endothelial dysfunction in pain sensitization among Jamaicans with sickle cell disease

Viscosity-vaso-occlusion (VVO) and haemolysis-endothelial dysfunction (HED) are pathophysiological mechanisms and clinical subphenotypes of sickle cell disease (SCD). Recurrent vaso-occlusive crises (VOC) may lead to neuroplastic changes and pain sensitization. Among 257 SCD participants, we assessed the relationship of subphenotypes with pain sensitivity using quantitative sensory testing to identify heat pain thresholds (HPT) and pressure pain thresholds (PPT). VOC history and sleep, social and emotional functioning were assessed using the Adult Sickle Cell Quality of Life Measurement Information System. The 'elbow method' determined the optimal number of clusters as three. Clustering was performed using K-prototypes. Among clusters 2 and 3, VOC frequency and severity were higher. Clusters 1 and 3 had lower haemoglobin, higher reticulocytes and lactate dehydrogenase and more leg ulcers. In multivariate regression, cluster 3 was associated with approximately 13.6% lower PPT compared to cluster 1, and female sex was associated with decreases in PPT and HPT at the hands and feet (p < 0.001). Hydroxyurea use and unit increases in sleep functioning and age were associated with approximately 20.1% higher foot-PPT, 6.8% higher hand-PPT and 2.5% higher hand-HPT and foot-HPT respectively. Findings suggest that a third subphenotype with mixed VVO and HED features and worse pain sensitization may exist.

Genetic contributions to pain modulation in sickle cell: A focus on single nucleotide polymorphisms

Background

Despite recent advances in our knowledge of genetic contributions to the highly variable sickle cell disease (SCD) phenotype, our understanding of genetic factors associated with pain sensitivity in SCD remains limited. Previous studies investigated specific variants in single candidate genes and their association with SCD pain variability. The primary aim of the current study was to expand the genes and polymorphisms tested to discover new risk genes (polymorphisms) associated with central sensitization for individuals with SCD.

Methods

Adults with sickle cell disease (n = 59, Mage = 36.8 ± 11.5, 65.8 % female) underwent quantitative sensory testing to examine central sensitization and general pain sensitivity. Participants reported average crisis and non-crisis pain intensities weekly using a 0-100 scale, and provided salivary samples for genotyping. The Hardy-Weinberg equilibrium was verified for controls, and allele distributions were tested with chi-square and odds ratio tests. The Benjamini-Hochberg procedure was used to control for false discovery rate. Regression analyses and Wilcoxon tests were used to test associations for normally distributed and skewed data, respectively.

Results

Central sensitization and general pain sensitivity were not associated with hemoglobin genotype (Ps > 0.05). Of 4145 SNPs tested, following false discovery rate adjustments, 11 SNPs (rs11575839, rs12185625, rs12289836, rs1493383, rs2233976, rs3131787, rs3739693, rs4292454, rs4364, rs4678, rs6773307) were significantly associated with central sensitization, and one SNP (rs7778077) was significantly associated with average weekly non-crisis pain. No SNPs were associated with general pain sensitivity.

Conclusions

These findings provide insights into genetic variants association with average non-crisis pain and central sensitization for individuals with SCD, and may provide support for genetic predictors of heightened pain experience within SCD.

An Examination of John Henryism in Adults Living with Sickle Cell Disease

BACKGROUND

John Henryism (JH) is a behavioral predisposition for high-effort coping with adversity. JH has been associated with hypertension in Black Americans with low socioeconomic status (SES) and is also found to be associated with psychological well-being. Sickle cell disease (SCD), a rare genetic disease largely affecting Black Americans in the United States, presents as a chronic condition that may benefit from a deeper understanding of the impact of JH on overall health.

PURPOSE

This study examined the association between high and low JH and diastolic blood pressure, systolic blood pressure, hypertension prevalence, and sleep function. We relied on the biopsychosocial transaction model to adjust for relevant clinical and sociodemographic variables.

METHODS

This was a cross-sectional secondary analysis of 274 adults with SCD living in the United States and recruited between 2014 and 2020. Study visits consisted of physical examinations, medical history, demographic, and psychosocial questionnaires. Adjusted linear regressions estimated associations between high and low JH and diastolic and systolic blood pressure as well as self-reported sleep function. Multivariable logistic regression was used to examine associations with hypertension prevalence.

RESULTS

High JH was significantly associated with lower diastolic blood pressure (β =  - 2.98; 95% confidence interval =  - 5.92, - 0.04) but higher sleep dysfunction (β = 2.76; 95% confidence interval = 1.45, 4.07).

CONCLUSIONS

Overall, we found positive psychological coping resources associated with high JH, with the exception of sleep.

TRIAL REGISTRATION

CLINICALTRIALS

gov Identifier: NCT02156102.

Sleep Disruption Moderates the Daily Dynamics of Affect and Pain in Sickle Cell Disease

Persons with sickle cell disease (SCD) often experience pain that can interfere with quality of life and daily activities. Pain can modulated by affect and sleep continuity; however, few studies have explored how these factors complementarily influence pain in adults with SCD. The study aims were to investigate 1) whether pain levels were heightened on days characterized by low positive affect and high negative affect, and 2) whether the relationship between affect and pain was intensified following nights of disrupted sleep. Adults with SCD (N = 25) completed ecological momentary assessments and daily sleep diaries. Mixed models were used to analyze the main and interactive effects of daily affect (positive affect and negative affect) and sleep disruption (wake after sleep onset and frequency of awakenings) on both daily average pain and daily maximum pain. Results suggested that daily average pain and maximum pain tended to be higher on days of low positive affect and high negative affect. Furthermore, the frequency of nocturnal awakenings moderated the relationship between positive affect and pain. On days where there were higher frequencies of nocturnal awakenings, low positive affect was associated with both average and maximum pain; however, this association was not observed with lower frequencies of nocturnal awakenings. The association between negative affect and maximum pain was also stronger at higher levels of awakenings. Results highlight the relevance of adjunctive interventions that target affect among populations with SCD and further suggest that sleep continuity may further facilitate these interventions, highlighting the importance of multimodal treatments. PERSPECTIVE: This study examined the effects of affect and sleep on pain among adults with sickle cell disease (SCD). Higher pain occurred on days of low positive affect and high negative affect, particularly following nights of more frequent awakenings. These findings emphasize the importance of addressing affect and sleep in SCD treatment.

Poor Sleep Quality in Jamaican Adults With Sickle Cell Disease: Prevalence, Risk Factors, and Association With Quality of Life

Poor sleep and chronic illnesses have a bidirectional relationship where presence of one can worsen the other. Sickle cell disease (SCD) is associated with significant morbidity and early mortality. In this study, we examine sleep quality, its predictors, and its association with quality of life in Jamaican adults with SCD. This cross-sectional study evaluated 177 well adult SCD patients for sleep quality using The Pittsburgh Sleep Quality Index (PSQI) and quality of life using the Adult Sickle Cell Quality of Life Measurement Information System (ASCQ-Me). Multiple linear regression models examined the predictors of poor sleep quality. The mean global PSQI score was 6.9 (SD 4.2) with 56.5% having poor sleep quality. Women had significantly worse scores for sleep efficiency (p 0.005), sleep latency (p 0.03) and higher use of sleeping medications (p 0.02). Those overweight/obese had significantly worse subjective sleep quality (p 0.001) and sleep efficiency (p 0.05). In multivariate regression analysis, overweight individuals had poorer sleep quality (OR: 2.9; 95% C.I.: 1.07, 7.88) than those with normal weight whereas those unemployed and looking for a job had lower prevalence of poor sleep quality (OR 0.2; 95% C.I.: 0.05, 0.77) compared to employed individuals. Participants with good sleep quality had significantly better functioning in all 5 domains of the ASCQ-Me. In conclusion, persons with SCD who are overweight or obese are at increased risk of poor sleep which can negatively affect quality of life. Patient populations and healthcare providers will need to manage the emerging burden of overweight/obesity.

Psychiatric comorbidities in adults with sickle cell disease: A narrative review

Although descriptions of quality of life and patient reports of mood in sickle cell disease (SCD) have become more common in the literature, less is known about psychiatric illness prevalence, presentation, and treatment, particularly for adults. We provide a narrative review of what is known about common and debilitating psychiatric conditions such as depression, anxiety, and cognitive impairment, specifically for adults with SCD. We discuss the limitations of the current evidence, make provisional recommendations, and identify opportunities for research and improved care.

Sleep-EEG in comorbid pain and insomnia: implications for the treatment of pain disorders

Introduction

Patients with chronic pain experience a high prevalence of comorbid insomnia, which is associated with functional impairment. Recent advances in sleep electroencephalography (sleep-EEG) may clarify the mechanisms that link sleep and chronic pain. In this clinical update, we outline current advancements in sleep-EEG assessments for pain and provide research recommendations.

Results

Promising preliminary work suggests that sleep-EEG spectral bands, particularly beta, gamma, alpha, and delta power, may create candidate neurophysiological signatures of pain, and macro-architectural parameters (e.g., total sleep time, arousals, and sleep continuity) may facilitate EEG-derived sleep phenotyping and may enable future stratification in the treatment of pain.

Conclusion

Integration of measures obtained through sleep-EEG represent feasible and scalable approaches that could be adopted in the future. We provide research recommendations to progress the field towards a deeper understanding of their utility and potential future applications in clinical practice.

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

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

Preliminary Evidence for the Sequentially Mediated Effect of Racism-Related Stress on Pain Sensitivity Through Sleep Disturbance and Corticolimbic Opioid Receptor Function

Sleep disturbance predicts worse pain outcomes. Because sleep disturbance inequitably impacts Black adults - with racism as the upstream cause - understanding how racism-related stress impacts pain through sleep might help minimize racialized pain inequities. This preliminary study examined sequential mediation of the effect of racism-related stress on experimental pain through sleep disturbance and corticolimbic μOR function in pain-free non-Hispanic Black (NHB) and White (NHW) adults. Participants completed questionnaires, actigraphy, positron emission tomography, and sensory testing. We reproduced findings showing greater sleep disturbance and pain sensitivity among NHB participants; greater sleep disturbance (r = .35) and lower pain tolerance (r=-.37) were significantly associated with greater racism-related stress. In a sequential mediation model, the total effect of racism-related stress on pain tolerance (β=-.38, P = .005) weakened after adding sleep disturbance and ventromedial prefrontal cortex (vmPFC) μOR binding potential (BPND) as mediators (β = -.18, P = .16). The indirect effect was statistically significant [point estimate = -.003, (-.007, -.0003). Findings showed a potential sequentially mediated effect of racism-related stress on pain sensitivity through sleep disturbance and vmPFC μOR BPND. As policy efforts are enacted to eliminate the upstream cause of systemic racism, these results cautiously suggest that sleep interventions within racism-based trauma informed therapy might help prevent downstream effects on pain. PERSPECTIVE: This preliminary study identified the effect of racism-related stress on pain through sleep disturbance and mu-opioid receptor binding potential in the ventromedial prefrontal cortex. Findings cautiously support the application of sleep interventions within racism-based trauma-informed therapy to prevent pain inequities as policy changes function to eliminate all levels of racism.

Sleep quality and pain in adolescents and young adults with sickle cell disease

STUDY OBJECTIVES

This study evaluated sleep quality in relation to pain and pain-related impairment in adolescents and young adults with sickle cell disease. The purpose was to examine whether increased age was associated with poorer sleep quality and pain and to examine the sleep quality-pain association in this age group.

METHODS

Eighty-nine adolescents and young adults with sickle cell disease between the ages of 13 and 25 completed ratings of sleep quality, overall pain, and 2 measures of pain-related impairment (pain impact and pain burden) as part of their clinical care. Retrospective chart reviews were completed to match ratings to demographic and medical characteristics. Correlations and multiple regression were used to examine associations between age, sleep quality, and pain variables, including an exploratory analysis of the sleep-pain association by age.

RESULTS

Increased age was associated with poorer sleep quality, worse overall pain, and higher pain burden. Poorer sleep quality was also associated with worse overall pain and pain burden. Using multiple regression, a small, but not statistically significant trend was observed for the interaction of increased age and strengthening of the sleep quality-pain burden association.

CONCLUSIONS

Sleep quality and pain are important challenges for adolescents and young adults with sickle cell disease that may persist or worsen with increased age. Early identification of these difficulties in pediatric populations as well as continued screening and intervention as adolescents transition into adult care is important. Additional longitudinal research is needed to better understand the progression of the sleep-pain relationship over time.

CITATION

Schlenz AM, Thomas SJ, Gloston G, Lebensburger J, Maxwell SL, Kanter J. Sleep quality and pain in adolescents and young adults with sickle cell disease. J Clin Sleep Med. 2022;18(12):2845-2853.

"Into the Lion's Den": COVID-19 Experiences of Black Adults with Sickle Cell Disease

Adults living with sickle cell disease are at risk for experiencing severe illness from coronavirus disease 2019 (COVID-19) due to the complexity of their disease. Additionally, self-management and navigating the healthcare system may be challenging during the COVID-19 pandemic. Therefore, we conducted telephone interviews with 25 participants to explore the experiences of Black adults living with sickle cell disease during the early months of the pandemic in the United States. Three overarching themes characterize their experiences: management of sickle cell disease was further complicated by the pandemic, fear of the virus contributed to physical and social isolation, and employment and financial challenges affected well-being. The pandemic contributed to changes in health care maintenance and had a disproportionate impact on this population. Addressing social and structural determinants of health and disruptions in health care accessibility is critical to advancing health and health care equity for individuals living with sickle cell disease.

A Needs Assessment of Persons With Sickle Cell Disease in a Major Medical Center in North Carolina

BACKGROUND Sickle cell disease (SCD) is a complex disease associated with many complications and a shortened lifespan. In 2016, the National Heart, Lung and Blood Institute funded 8 centers in the United States to form the Sickle Cell Disease Implementation Consortium, with the goal of improving SCD care. The aim of our study was to describe SCD self-efficacy, pain interference, and barriers to care from the perspective of persons with SCD in the North Carolina center.METHODS Persons with SCD, aged 15 and older were recruited from a large SCD center in North Carolina. Surveys, focus groups, and interviews were completed.RESULTS Fifty-one people completed a survey, and 14 people completed an interview or focus group. Barriers identified in the survey included self-care barriers, misconceptions related to hydroxyurea (an oral medication that reduces rates of pain crisis), limited provider knowledge, and stigma. Concerning self-efficacy, participants reported that they were able to manage their pain symptoms most of the time. Pain interfered most with the ability to participate in social and day-to-day activities.Common themes from the focus groups and interviews included misconceptions about hydroxyurea, pain, provider knowledge, stigma, co-management, transportation, and insurance. Recommendations to improve care included the use of case managers, utilization of treatment guidelines, individualized pain protocols, and effective co-management by providers.LIMITATIONS Participants were recruited from 1 SCD center and may not be representative of the entire SCD population in North Carolina.CONCLUSIONS Participants described many perceived barriers to care, and their responses suggest a need for improvements in patient hydroxyurea education, provider knowledge, and care coordination.

Pain in sickle cell disease: current and potential translational therapies

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

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

OBJECTIVES

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

MATERIALS AND METHODS

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

RESULTS

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

DISCUSSION

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

A Preliminary Investigation of the Underlying Mechanism Associating Daily Sleep Continuity Disturbance and Prescription Opioid Use Among Individuals With Sickle Cell Disease

BACKGROUND

There are emerging data indicating that sleep disturbance may be linked with an increase in opioid use. The majority of sickle cell disease (SCD) patients experience sleep disturbances, which can elevate pain severity and pain catastrophizing, both of which are important predictors of opioid consumption.

PURPOSE

We conducted a preliminary investigation on the association between previous night sleep disturbance and short-acting opioid use, as well as the potential mediating roles of pain severity and pain catastrophizing. Because sex is associated with sleep disturbance, pain-related experiences, and opioid use, we also explored the potential moderating role of sex.

METHODS

Participants were 45 SCD patients who were prescribed opioids. For 3 months, sleep diaries were collected immediately upon participants' awakening. Daily pain severity, pain catastrophizing, and prescription opioid use measures were collected before bedtime.

RESULTS

Multilevel structural equation modeling revealed that wake time after sleep onset (WASO) during the previous night (Time 1) predicted greater short-acting opioid use during the next day (Time 2). Pain severity and pain catastrophizing measured during the next day (Time 2) also mediated the association between the two. Sex moderation analysis showed that the positive association between WASO and pain severity was largely driven by women.

CONCLUSION

These findings provide some preliminary evidence as to the mechanism linking sleep continuity disturbance and opioid requirement in SCD patients. Future studies should replicate and extend these findings with clearer temporal information and employing more refined measures of sleep continuity and prescription opioid use in a larger sample.

Sleep disturbance in adults with sickle cell disease: relationships with executive and psychological functioning

Sleep disturbance is common among children with sickle cell disease (SCD) and is related to neurocognitive difficulties. However, research on sleep disturbances and related variables among adults with SCD is extremely limited. The present study examined the relationship between sleep, executive functioning, and emotional functioning among 62 adults (29 females; M age = 32 years, SD = 7.79) with SCD preparing to undergo a stem cell transplant. Participants were administered a neurocognitive evaluation that included objective and subjective measures of executive functioning, and they completed PROMIS self-report measures of anxiety, depression, and pain intensity. Results showed that about 17% of participants endorsed clinically significant sleep disruptions, while 16.1% and 8% endorsed clinically significant symptoms of anxiety and depression, respectively. Sleep disturbance in these adults was not significantly correlated with objective or subjective measures of executive functioning. Moreover, anxiety, but not depression, was a significant mediator between self-reported sleep difficulties and both objective and subjective measures of executive functioning while controlling for pain intensity. Future research on sleep interventions will be essential for ameliorating the effects of sleep disturbance on executive functioning and anxiety among adults with SCD.

Key Components of Pain Management for Children and Adults with Sickle Cell Disease

Sickle cell disease pain manifests as severe acute pain episodes and a debilitating chronic pain syndrome. Acute pain episodes are the most common reason for health care use; however, acute pain episodes are also frequently managed at home. Chronic pain syndrome develops in 30% to 40% of individuals with sickle cell disease, with an increasing incidence and severity with age. We review the critical aspects of pain management that are integral to the comprehensive approach to sickle cell disease pain and are rooted in the biopsychosocial model. The review focuses on opioid pharmacology and psychosocial comorbidities.

Predicting Responses to Pregabalin for Painful Diabetic Peripheral Neuropathy Based on Trajectory-Focused Patient Profiles Derived from the First 4 Weeks of Treatment

INTRODUCTION

Prediction of final clinical outcomes based on early weeks of treatment can enable more effective patient care for chronic pain. Our goal was to predict, with at least 90% accuracy, 12- to 13-week outcomes for pregabalin-treated painful diabetic peripheral neuropathy (pDPN) patients based on 4 weeks of pain and pain-related sleep interference data.

METHODS

We utilized active treatment data from six placebo-controlled randomized controlled trials (n = 939) designed to evaluate efficacy of pregabalin for reducing pain in patients with pDPN. We implemented a three-step, trajectory-focused analytics approach based upon patient responses collected during the first 4 weeks using monotonicity, path length, frequency domain (FD), and k-nearest neighbor (kNN) methods. The first two steps were based on combinations of baseline pain, pain at 4 weeks, weekly monotonicity and path length during the first 4 weeks, and assignment of patients to one of four responder groups (based on presence/absence of 50% or 30% reduction from baseline pain at 4 and at 12/13 weeks). The third step included agreement between prediction of logistic regression of daily FD amplitudes and assignment made from kNN analyses.

RESULTS

Step 1 correctly assigned 520/939 patients from the six studies to a responder group using a 3-metric combination approach based on unique assignment to a 50% responder group. Step 2 (applied to the remaining 419 patients) predicted an additional 121 patients, using a blend of 50% and 30% responder thresholds. Step 3 (using a combination of FD and kNN analyses) predicted 204 of the remaining 298 patients using the 50% responder threshold. Our approach correctly predicted 90.0% of all patients.

CONCLUSION

By correctly predicting 12- to 13-week responder outcomes with 90% accuracy based on responses from the first month of treatment, we demonstrated the value of trajectory measures in predicting pDPN patient response to pregabalin.

TRIAL REGISTRATION

www.clinicaltrials.gov identifiers, NCT00156078/NCT00159679/NCT00143156/NCT00553475.

FUNDING

Pfizer. Plain language summary available for this article.

Daily Opioid Use Fluctuates as a Function of Pain, Catastrophizing, and Affect in Patients With Sickle Cell Disease: An Electronic Daily Diary Analysis

Chronic opioid therapy is a common treatment regimen for patients with sickle cell disease (SCD), a chronically painful recessive hemoglobinopathy. The collective risk profile of chronic opioid therapy necessitates an understanding of which pain-related factors, such as affect and pain catastrophizing, are associated with the ebbs and flows of opioid use in daily life, a topic that has received very little attention among patients with any type of chronically painful condition, including SCD. We therefore investigated the variability of day-to-day patterns of short- and long-acting opioid use and their associations with pain and pain-related cognitive and affective processes in daily life among patients with SCD using a nightly electronic diary (N = 45). Opioid use was self-reported and converted into oral morphine equivalents for analysis, which was conducted with mixed effects modeling. Results indicated that greater pain and pain catastrophizing were associated with greater use of short-acting opioids, and negative affect was associated with greater use of long-acting opioids. Additionally, the association of pain and short-acting opioid use was moderated by pain catastrophizing, showing that opioid use was elevated when patients catastrophized about their pain, even if they reported low levels of pain. These findings suggest that monitoring pain-related cognitive and affective variables may be a useful approach to understanding risk for problematic opioid use in patients with daily pain.

PERSPECTIVE

The present study shows that pain and pain-related cognitive and affective variables are associated with daily variation in prescription opioid use in SCD. The findings may have broad implications for tracking and defining risk for prescription opioid misuse in patients with daily pain.

Mid-Treatment Sleep Duration Predicts Clinically Significant Knee Osteoarthritis Pain reduction at 6 months: Effects From a Behavioral Sleep Medicine Clinical Trial

Study Objectives

To determine the relative influence of sleep continuity (sleep efficiency, sleep onset latency, total sleep time [TST], and wake after sleep onset) on clinical pain outcomes within a trial of cognitive behavioral therapy for insomnia (CBT-I) for patients with comorbid knee osteoarthritis and insomnia.

Methods

Secondary analyses were performed on data from 74 patients with comorbid insomnia and knee osteoarthritis who completed a randomized clinical trial of 8-session multicomponent CBT-I versus an active behavioral desensitization control condition (BD), including a 6-month follow-up assessment. Data used herein include daily diaries of sleep parameters, actigraphy data, and self-report questionnaires administered at specific time points.

Results

Patients who reported at least 30% improvement in self-reported pain from baseline to 6-month follow-up were considered responders (N = 31). Pain responders and nonresponders did not differ significantly at baseline across any sleep continuity measures. At mid-treatment, only TST predicted pain response via t tests and logistic regression, whereas other measures of sleep continuity were nonsignificant. Recursive partitioning analyses identified a minimum cut-point of 382 min of TST achieved at mid-treatment in order to best predict pain improvements 6-month posttreatment. Actigraphy results followed the same pattern as daily diary-based results.

Conclusions

Clinically significant pain reductions in response to both CBT-I and BD were optimally predicted by achieving approximately 6.5 hr sleep duration by mid-treatment. Thus, tailoring interventions to increase TST early in treatment may be an effective strategy to promote long-term pain reductions. More comprehensive research on components of behavioral sleep medicine treatments that contribute to pain response is warranted.

Disease-Related, Nondisease-Related, and Situational Catastrophizing in Sickle Cell Disease and Its Relationship With Pain

Catastrophizing is a potent psychological modulator of pain across several chronic pain populations; yet despite evidence that patients with sickle cell disease (SCD) catastrophize more than patients with other chronic pain conditions, previous research indicates that catastrophizing is not related to sickle cell pain after controlling for relevant covariates such as depression. Recent research suggests that pain-related catastrophizing should be assessed across pain contexts (eg, dispositional and situational). In this study, we measured disease-specific, general non-disease-related, and situational catastrophizing and assessed the relationship between these contextual dimensions of catastrophizing and laboratory and clinical pain among patients with SCD. Results revealed differential catastrophizing across pain contexts, with patients reporting greater catastrophizing about SCD-specific pain compared with non-SCD pain and laboratory pain. SCD-specific and non-SCD catastrophizing were associated with clinical pain outcomes, and situational catastrophizing with markers of central sensitization and laboratory pain. Further examination of the time course of laboratory responses revealed that increases in situational catastrophizing were associated with subsequent increases in laboratory pain sensitivity. Taken together, results show the relevance of catastrophizing in understanding pain in SCD, and suggest that context-specific anchors may be beneficial in predicting different aspects of the pain experience (eg, chronic pain, pain sensitization).

PERSPECTIVE

Patients with SCD report greater catastrophizing about sickle cell-specific pain relative to other pains. Disease-specific and non-disease-related pain catastrophizing were associated with clinical pain, and situational catastrophizing predictive of subsequent laboratory pain. Evaluation of context-specific catastrophizing may more accurately predict different aspects of the pain experience.

An Evaluation of Central Sensitization in Patients With Sickle Cell Disease

Central sensitization (CS), nociceptive hyperexcitability known to amplify and maintain clinical pain, has been identified as a leading culprit responsible for maintaining pain in several chronic pain conditions. Recent evidence suggests that it may explain differences in the symptom experience of individuals with sickle cell disease (SCD). Quantitative sensory testing (QST) can be used to examine CS and identify individuals who may have a heightened CS profile. The present study categorized patients with SCD on the basis of QST responses into a high or low CS phenotype and compared these groups according to measures of clinical pain, vaso-occlusive crises, psychosocial factors, and sleep continuity. Eighty-three adult patients with SCD completed QST, questionnaires, and daily sleep and pain diaries over a 3-month period, weekly phone calls for 3 months, and monthly phone calls for 12 months. Patients were divided into CS groups (ie, no/low CS [n = 17] vs high CS [n = 21]), on the basis of thermal and mechanical temporal summation and aftersensations, which were norm-referenced to 47 healthy control subjects. High CS subjects reported more clinical pain, vaso-occlusive crises, catastrophizing, and negative mood, and poorer sleep continuity (Ps < .05) over the 18-month follow-up period. Future analyses should investigate whether psychosocial disturbances and sleep mediate the relationship between CS and pain outcomes.

PERSPECTIVE

In general, SCD patients with greater CS had more clinical pain, more crises, worse sleep, and more psychosocial disturbances compared with the low CS group.