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

Estradiol is Pro-Nociceptive and Associated with a Small-Fiber Neuropathy Among Premenopausal Women with Sickle Cell Disease

Vaso-occlusive crisis (VOC) pain episodes often occur with menses and concurrent hormonal contraceptive use may reduce their frequency. This study tested the hypothesis that among women with sickle cell disease (SCD), sex hormones are associated with pain detection thresholds. Women with SCD aged minimum 18 years with regular menses, and without acute illnesses, pregnancy, oophorectomy, or hormonal contraceptive use within three months prior were included. Pain detection thresholds for heat (HPT) and pressure (PPT), and serum estradiol, progesterone and testosterone were measured at follicular and luteal phases. The Adult Sickle Cell Quality-of-Life Measurement Information System assessed quality-of-life and VOC frequency and severity scores. Generalized linear mixed models were performed, including the day of the cycle standardized by cycle length. Among 125 participants, neither the day nor phase of the menstrual cycle was associated with PPT or HPT. In multivariate analyses, worse VOC scores (β = 1.7) and severe genotype (β = -46.0) were associated with higher and lower trapezius PPT, respectively. Older age was associated with lower forearm HPT (β = -0.1). Among leg measurements, ovulatory cycles (β = -1.1) and hydroxyurea use (β = -1.2) were associated with lower HPT, while worse VOC scores (β = 0.1) were associated with higher HPT. Higher estradiol was associated with lower HPT at the leg (β = -0.02), with an interaction with the cycle day (β = 0.001) predicting lower thresholds earlier in the cycle for the same estradiol level. Estradiol is associated with a time-varying, length-dependent small-fiber neuropathy among SCD women; and may be a potential therapeutic target and biomarker for SCD pain.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSION

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

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.

Severe Pain Profiles and Associated Sociodemographic and Clinical Characteristics in Individuals With Sickle Cell Disease

OBJECTIVE

The aim of this study was to identify classes of individuals with sickle cell disease (SCD) who share distinct severe pain profiles and evaluate differences in demographic, clinical, and psychosocial characteristics between classes.

METHODS

This exploratory, cross-sectional study used data collected for the SCD Implementation Consortium Research Registry at Duke University. Using Adult Sickle Cell Quality of Life-Measurement System pain-item data from 291 adults with SCD, latent class analysis was used to determine classes of individuals sharing distinct severe pain profiles. Bivariate analyses and logistic regression models were used to assess the relationships between pain profile classes and demographic, clinical, and psychosocial characteristics.

RESULTS

Three classes sharing distinct severe pain profiles were identified: Low Frequency and Impact class (n=73), Moderate Frequency and Impact class (n=94), and High Frequency and Impact class (n=124). When compared with the Low Frequency and Impact class and controlling for age and sex, individuals in the Moderate Frequency and Impact class were more likely to: be female (P=0.031) and unemployed (P=0.013); report worse sleep (P=0.005) and social functioning (P=0.005); have less emotional distress (P=0.004); describe pain as "sore" (P=0.002); and have previous SCD-related lung complications (P=0.016). When compared with the Low Frequency and Impact class, individuals in the High Frequency and Impact class: had worse social functioning (P<0.001) and previous SCD-related lung complications (P=0.006); described pain as "sore" (P<0.001); and were taking pain medication daily for SCD (P=0.001).

DISCUSSION

Severe pain experiences in SCD are complex; however, there are subgroups of people who report similar experiences of severe pain.