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Purpose: Women have a higher dry eye disease prevalence compared with men, although only relatively minor differences in the ocular surface have been observed. Interestingly, a sex difference in pain sensitivity is known, and recent research suggests that pain sensitivity is associated with dry eye symptoms. This study attempts to discern whether the association between pain sensitivity and dry eye symptoms varies between women and men., Methods: In this prospective cross-sectional study, subjects were seen for one visit where they were asked to fill out a set of questionnaires consisting of the Pain Sensitivity Questionnaire, Ocular Surface Disease Index (OSDI), and other dry eye questionnaires. This was followed by an ocular surface assessment on both eyes., Results: Two hundred eighty-seven subjects (194 women, 93 men) completed the study. Intersex differences in the ocular surface were noted. Even after accounting for these differences, an interaction effect between sex and Pain Sensitivity Questionnaire-minor score on dry eye symptoms was observed, with only women noting increased symptoms on the OSDI (P < 0.005) and other dry eye questionnaires (P values ranging from 0.01 to <0.005) with greater pain sensitivity. After controlling for other variables, women with the highest pain sensitivity had a 17-point higher OSDI score and greater symptoms, as reported by all the other dry questionnaires compared with their male counterparts., Conclusions: The role of pain sensitivity on dry eye symptoms appears to vary between women and men. This difference provides insight into why women have a significantly higher dry eye disease prevalence than men.

Objective: To examine the feasibility, acceptability, and effects of a home-based morning bright light treatment on pain, mood, sleep, and circadian timing in US veterans with chronic low back pain., Design: An open treatment trial with a seven-day baseline, followed by 13 days of a one-hour morning bright light treatment self-administered at home. Pain, pain sensitivity, mood, sleep, and circadian timing were assessed before, during, and after treatment., Setting: Participants slept at home, with weekly study visits and home saliva collections., Participants: Thirty-seven US veterans with medically verified chronic low back pain., Methods: Pain, mood, and sleep quality were assessed with questionnaires. Pain sensitivity was assessed using two laboratory tasks: a heat stimulus and an ischemia stimulus that gave measures of threshold and tolerance. Sleep was objectively assessed with wrist actigraphy. Circadian timing was assessed with the dim light melatonin onset., Results: Morning bright light treatment led to reduced pain intensity, pain behavior, thermal pain threshold sensitivity, post-traumatic stress disorder symptoms, and improved sleep quality (P < 0.05). Phase advances in circadian timing were associated with reductions in pain interference (r = 0.55, P < 0.05)., Conclusions: Morning bright light treatment is a feasible and acceptable treatment for US veterans with chronic low back pain. Those who undergo morning bright light treatment may show improvements in pain, pain sensitivity, and sleep. Advances in circadian timing may be one mechanism by which morning bright light reduces pain. Morning bright light treatment should be further explored as an innovative treatment for chronic pain conditions., (© 2018 American Academy of Pain Medicine. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Context: Vulvodynia is a chronic pain condition defined as vulvar pain lasting at least 3 months in the absence of gross anatomic or neurologic findings. Provoked, localized vulvodynia (PLV), a subtype of vulvodynia, is characterized by vestibular pain in response to light touch. The cause of PLV remains largely unknown, and triggering events have yet to be determined., Objective: To evaluate vestibular and peripheral experimental pain thresholds in patients with PLV to further define the somatosensory profile of these patients., Methods: After informed consent was provided, eligible participants completed a questionnaire and underwent quantitative sensory testing at the forearm and posterior vestibule. Detection and pain thresholds to thermal (cold and heat) and mechanical (pressure) stimuli were measured., Results: Seventeen participants with PLV and 16 control participants were included. Participants in the PLV group scored lower on the patient health questionnaire 9 (PHQ-9) compared with those in the control group (P<.05) and had higher ratings of self-reported genital pain with sex (P<.001) and daily activity (P<.05). Forearm pain thresholds to cold (P<.01) and heat (P<.01) stimuli were also lower in the PLV group compared with those in the control group. Vestibular pain thresholds to cold (P<.05) and pressure (P<.01) stimuli were also lower in the PLV group., Conclusion: Lower scores on the PHQ-9 and higher self-reported genital pain ratings of patients with PLV highlight the significant impact of this poorly understood condition on quality of life. Quantitative sensory testing results demonstrated that vestibular cold allodynia may be a somatosensory feature of PLV. Reduced forearm pain thresholds in these patients suggest altered sensory processing at extrapelvic sites, although it is unclear whether these measurements are related to central sensitization.

Multiple studies in healthy populations and clinical samples have shown that ethnic minorities have greater pain sensitivity than their majority counterparts. Acculturation is speculated to be one of the sociocultural factors contributing to pain sensitivity since cultural beliefs and practices can influence the way patients perceive and respond to pain. However, the relationship of acculturation to pain sensitivity in minority populations remains poorly understood. Therefore, in this cross-sectional study, we examined the relationship between acculturation and experimental pain sensitivity in 50 Asian Americans residing in North Central Florida with knee osteoarthritis pain. The Suinn-Lew Asian Self Identity Acculturation Scale was used to assess acculturation, and multimodal quantitative sensory testing was performed to measure experimental sensitivity, including heat pain tolerance, pressure pain threshold, and punctate mechanical pain. Descriptive and regression analyses were performed. Participants' mean age was 55.7 years, and about half of this sample were Korean American (56%). The participants had lived in the United States for 21 years on average. Regression analyses indicated that lower acculturation to American culture may contribute to greater experimental pain sensitivity. Asian Americans who were more acculturated to the American culture had higher heat pain tolerance (beta = 0.61, P =0.01), higher pressure pain threshold (beta = 0.59, P =0.02), and lower ratings of punctate mechanical pain (beta = -0.70, P < 0.01). These findings add to the literature regarding sociocultural factors associated with pain in Asian Americans; additional research with a larger and more diverse sample of Asian Americans is warranted for cross-validation.

Background: Studies on relationships between sex, ethnicity, and pain have largely emanated from the United States and Europe. We compared cold (CPT) and pressure pain tolerance (PPT) in male and female South Africans of African and European ancestry and assessed whether psychosocial factors (including pain beliefs) predicted differences in pain tolerance., Methods: We recruited 106 (62 female) students of African ancestry and 106 (55 female) of European ancestry and subjected them to a cold-pressor test and pressure algometry. Socioeconomic status (SES), pain catastrophizing, depression, anxiety, and pain beliefs were assessed as predictors of pain tolerance., Results: CPT was lower in students of African compared with European ancestry (for both sexes), and PPT was lower in female than male students (for both ethnicities). Females were very accepting of men expressing pain and males less so. Males of African ancestry were least accepting but still tolerant. Multivariate analysis identified African ancestry, and particularly being a female of African ancestry, as strong predictors of lower CPT. Anxiety was a weak predict or of CPT. Sex was the only strong predictor of PPT on multivariate analysis (PPT females < males), and catastrophizing was a weak predictor. Female sex and African ancestry were strong predictors of acceptance of expression of pain in males. SES was a weak predictor of the Appropriate Pain Behavior Questionnaire-Malescore., Conclusions: Despite different cultural and social backgrounds from US and European cohorts, we saw similar patterns of sex and ethnic differences in CPT and PPT in an African cohort. Traditional psychosocial predictors of pain sensitivity predicted variation in the outcome variables but were not strong predictors., (© 2017 American Academy of Pain Medicine. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com)

Objectives: To quantify the influence of abuse, particularly in childhood, with pain sensitivity and other adverse symptoms experienced by women with fibromyalgia (FM)., Methods: Subjects with FM completed a detailed abuse interview, dolorimetry, and questionnaire-based assessments of fatigue, cognitive self-appraisal, and depression. Student's t- and chi-square tests were used to analyse differences in FM symptoms between those with and without a history of childhood abuse. Linear regression was used to evaluate the relationship between abuse and symptom severity, adjusting for possible confounders., Results: In 111 women with FM, physical abuse during childhood demonstrated a clinically modest, yet statistically significant, association with increased tenderness as measured by pain pressure thresholds (β=-0.25, p=0.011) and tender points (β=0.23, p=.022). Physical child abuse was also associated with cognitive language impairment after adjusting for depression (β=0.27, p=0.001). While emotional child abuse was associated with fatigue, the association did not persist after adjustment for depressive symptoms., Conclusions: Group differences are of small magnitude and might not directly impact clinical practice, however, the experience of child abuse is associated with FM symptom severity and may shape the biological development of interoception in ways that predispose to pain and polysymptomatic distress.

Objective: A self-reported history of childhood physical and/or sexual abuse is frequently reported among chronic pain populations and has been associated with poorer adjustment to pain. In addition, self-reported abuse history has been related to increased pain complaints in population-based studies. One possible explanation for the association between abuse and clinical pain is that abuse victims may display enhanced sensitivity to painful stimuli, which increases the risk of developing clinical pain. However, the limited evidence addressing this issue has been mixed. The purpose of this study was to examine the association between self-reported history of childhood sexual or physical abuse and experimental pain responses in a nonclinical sample of generally healthy young adults., Design: Participants were 110 (56 female, 54 male) college students who completed a series of questionnaires assessing abuse history, recent pain, health care utilization, perceived health, and psychologic variables. Also, measures of thermal and ischemic pain threshold and tolerance were obtained in all participants. In addition, a procedure assessing temporal summation of heat pain was conducted in which intensity and unpleasantness ratings of repetitive thermal stimuli were obtained. Systolic and diastolic blood pressure and heart rate were assessed at resting and during the ischemic pain task., Results: Participants with a positive childhood abuse history were oversampled, yielding 21 out of 56 (37.5%) women with a positive history of abuse and 13 out of 54 (24.1%) PHA men. No abuse group differences emerged for thermal or ischemic pain thresholds or tolerances (P values>0.05). However, compared to women with no childhood abuse history, women with a positive history of abuse provided significantly lower average pain unpleasantness and peak pain unpleasantness ratings and lower unpleasantness ratings of the first trial during the temporal summation procedure, whereas no abuse group differences emerged for men. Also, compared to participants with no childhood abuse history, participants of both genders with a positive history of abuse demonstrated smaller increases (ie, less temporal summation) in pain unpleasantness ratings across trials of thermal stimulation, and participants with a positive history of abuse showed greater decreases in pain intensity and unpleasantness after reaching their peak pain level (ie, greater wind-down) compared to participants with no childhood abuse history. In addition, participants with a positive history of abuse reported more sites of recent pain, poorer perceived health, greater somatization, and more negative affect. No group differences in resting cardiovascular measures or cardiovascular reactivity were observed., Conclusion: These findings indicate that a self-reported history of childhood abuse is associated with decreased sensitivity to experimentally induced pain, especially among women. However, abuse history was associated with increased pain complaints, poorer self-reported health, and greater negative affect. These data highlight the complexity of the relationship between abuse history and pain and illustrate the need for further investigation of potential pain-related correlates of abuse.

Objective: Although numerous studies have reported ethnic differences in the prevalence and severity of clinical pain, little is known about how these differences affect the perception of experimental pain. The present experiment examined the effects of ethnicity (African American vs. white) on thermal pain responses in a healthy undergraduate population., Methods: Thirty white subjects (16 women and 14 men) and 18 African Americans (10 women and 8 men) participated in the study. Thermal testing included evaluation of the following: warmth thresholds, thermal pain thresholds, thermal pain tolerances, and magnitude estimates of both the intensity and unpleasantness of thermal pain (at 46 degrees, 47 degrees, 48 degrees, and 49 degrees C)., Results: Although no group differences emerged for warmth thresholds, thermal pain thresholds, or pain intensity ratings, African Americans demonstrated lower thermal pain tolerances than whites. In addition, African Americans had smaller slopes and larger intercepts than whites for ratings of pain unpleasantness. Additional analyses suggested that these findings were a consequence of group differences in thermal pain unpleasantness ratings at the lowest temperatures assessed (46 degrees and 47 degrees C); at these temperatures, African Americans rated the stimuli as more unpleasant than whites. Finally, group differences in thermal pain tolerance and thermal pain unpleasantness ratings seemed to partially account for greater self-reported daily pain symptoms among African Americans., Conclusions: Collectively, these findings seem to suggest ethnic differences in the perception of the affective-motivational dimension of thermal pain.