Cynthia D. Myers

Sex differences in the perception of noxious experimental stimuli: a meta-analysis

&NA; Fillingim and Maixner (Fillingim, R.B. and Maixner, W., Pain Forum, 4(4) (1995) 209–221) recently reviewed the body of literature examining possible sex differences in responses to experimentally induced noxious stimulation. Using a ‘box score’ methodology, they concluded the literature supports sex differences in response to noxious stimuli, with females displaying greater sensitivity. However, Berkley (Berkley, K.J., Pain Forum, 4(4) (1995) 225–227) suggested the failure of a number of studies to reach statistical significance suggests the effect may be small and of little practical significance. This study used meta‐analytic methodology to provide quantitative evidence to address the question of the magnitude of these sex differences in response to experimentally induced pain. We found the effect size to range from large to moderate, depending on whether threshold or tolerance were measured and which method of stimulus administration was used. The values for pressure pain and electrical stimulation, for both threshold and tolerance measures, were the largest. For studies employing a threshold measure, the effect for thermal pain was smaller and more variable. The failures to reject the null hypothesis in a number of these studies appear to have been a function of lack of power from an insufficient number of subjects. Given the estimated effect size of 0.55 threshold or 0.57 for tolerance, 41 subjects per group are necessary to provide adequate power (0.70) to test for this difference. Of the 34 studies reviewed by Fillingim and Maixner, only seven were conducted with groups of this magnitude. The results of this study compels to caution authors to obtain adequate sample sizes and hope that this meta‐analytic review can aid in the determination of sample size for future studies.

Gender role expectations of pain: relationship to experimental pain perception.

&NA; The primary purpose of this study was to investigate the influence of an individuals Gender Role Expectations of Pain (GREP) on experimental pain report. One hundred and forty‐eight subjects (87 females and 61 males) subjects underwent thermal testing and were asked to report pain threshold, pain tolerance, VAS ratings of pain intensity and unpleasantness, and a computerized visual analogue scales (VAS) rating of pain intensity during the procedure. Subjects completed the GREP questionnaire to assess sex‐related stereotypic attributions of pain sensitivity, pain endurance, and willingness to report pain. Consistent with previous research, significant sex differences emerged for measures of pain threshold, pain tolerance, and pain unpleasantness. After statistically controlling for age, GREP scores were significant predictors of threshold, tolerance, and pain unpleasantness, accounting for an additional 7, 11, and 21% of the variance, respectively. Sex remained a significant predictor of pain tolerance in hierarchical regression analyses after controlling for GREP scores. Results provide support for two competing but not mutually exclusive hypotheses related to the sex differences in experimental pain. Both psychosocial factors and first‐order, biological sex differences remain as viable explanations for differences in experimental pain report between the sexes. It appears that GREP do play a part in determining an individuals pain report and may be contributing to the sex differences in the laboratory setting.

The Coping Strategies questionnaire : A large sample, item level factor analysis

OBJECTIVE The Coping Strategies Questionnaire (CSQ), a measure of coping in chronic pain patients, was subjected to item-level exploratory factor analysis. SUBJECTS A sample of 965 chronic pain patients were used in the analysis. RESULTS Principal components analysis using a varimax rotation procedure identified nine factors that accounted for 54.5% of the variance. Of these nine factors, the first five represent subscales of the original CSQ subscales. The catastrophizing subscale replicated with significant loadings for all six original items, and ignoring sensations replicated with five of six items. Factors representing reinterpreting pain sensations, coping self-statements, and diverting attention subscales also appeared. The items from the praying and hoping subscale split into separate praying and hoping factors (factors 6 and 8). When reliability coefficients were calculated, factors 7 through 9 had unacceptably low internal consistency and thus were not considered stable factors. Correlations between factors 1 through 6 and other measures of psychological and physical functioning were calculated in the construct validation portion of this study. Previously found relationships were replicated in that the correlations between CSQ factor scores and measures of pain, depression, and disability were in the same direction in this data set as those previously reported.

Racial/ethnic differences in the experience of chronic pain.

&NA; The purpose of this study was to examine racial/ethnic‐related differences in a four‐stage model of the processing of chronic pain. The subjects were 1557 chronic pain patients (White=1084, African American=473) evaluated at a pain management clinic at a large southeastern university medical center. Using an analysis of covariance controlling for pain duration and education, African American patients reported significantly higher levels of pain unpleasantness, emotional response to pain, and pain behavior, but not pain intensity than Whites. Differences were largest for the unpleasantness and emotion measures, particularly depression and fear. The groups differed by approximately 1.0 visual analogue scale unit, a magnitude that may be clinically significant. Racial/ethnic differences in the linear relationship between stages were also tested using structural equation modeling and LISREL‐8. The results indicate differences in linear associations between pain measures with African Americans showing a stronger link between emotions and pain behavior than Whites.

Psychosocial contributions to sex-correlated differences in pain.

Abstract: Sex‐correlated differences in pain perception and behavior have been reported in several studies. Where such differences are found, they are most often in the direction of girls and women reporting more pain than is reported by boys and men. Although biologic, psychologic, and sociocultural factors act interdependently to influence pain responding, most efforts to explain sex‐correlated differences in pain have focused on first‐order biologic differences between the sexes. The current paper discusses empirical and theoretical literature addressing gender role socialization, cognitive factors, and affective factors associated with sex‐correlated differences in pain. We affirm that there is convincing evidence that such psychosocial factors must be taken into account in research on sex‐correlated differences in pain. We contend that the use of the dichotomous variable sex as a proxy for presumed biologic aspects of being female or male may obscure the contribution to sex‐correlated differences that could be ascribed to the ways in which women and men are socialized with respect to pain perception and pain reporting.

Sex, Gender, and Blood Pressure: Contributions to Experimental Pain Report

Objective The current study investigated whether the relationship between sex and experimental pain report was explained by systolic blood pressure (SBP) at rest or during pain task, by gender-role socialization as assessed by the Bem Sex Role Inventory, or both. The influence of gender-role socialization on pain report is often inferred but rarely studied. Methods Fifty female and 54 male healthy, young adults completed the Bem Sex Role Inventory and then underwent a cold pressor task. Blood pressure was assessed before and during pain testing. Results Univariate analyses indicated significant sex-related differences in pain threshold and pain tolerance. Baseline SBP was positively related to pain tolerance but did not explain sex differences, in accord with previous research. The Bem Sex Role Inventory demonstrated a relationship with pain, but did not explain sex differences. Conclusions We suggest that context-specific measures of gender are needed to assess gender-related pain behaviors in specific situations. Results from the current study support our contention that gender is part of sex as commonly measured. Also, blood pressure does not appear to fully account for sex-related differences in pain.

Massage for mechanical neck disorders: A systematic review

Study Design. Systematic review. Objective. To assess the effects of massage on pain, function, patient satisfaction, cost of care, and adverse events in adults with neck pain. Summary of Background Data. Neck pain is common, disabling, and costly. Massage is a commonly used modality for the treatment of neck pain. Methods. We searched several databases without language restriction from their inception to September 2004. We included randomized and quasirandomized trials. Two reviewers independently identified studies, abstracted data, and assessed quality. We calculated the relative risks and standardized mean differences on primary outcomes. Trials could not be statistically pooled because of heterogeneity in treatment and control groups. Therefore, a levels-of-evidence approach was used to synthesize results. Results. Overall, 19 trials were included, with 12/19 receiving low-quality scores. Descriptions of the massage intervention, massage professional’s credentials, or experience were frequently missing. Six trials examined massage as a stand-alone treatment. The results were inconclusive. Results were also inconclusive in 14 trials that used massage as part of a multimodal intervention because none were designed such that the relative contribution of massage could be ascertained. Conclusions. No recommendations for practice can be made at this time because the effectiveness of massage for neck pain remains uncertain. Pilot studies are needed to characterize massage treatment (frequency, duration, number of sessions, and massage technique) and establish the optimal treatment to be used in subsequent larger trials that examine the effect of massage as either a stand-alone treatment or part of a multimodal intervention. For multimodal interventions, factorial designs are needed to determine the relative contribution of massage. Future reports of trials should improve reporting of the concealment of allocation, blinding of outcome assessor, adverse events, and massage characteristics. Standards of reporting for massage interventions, similar to Consolidated Standards of Reporting Trials, are needed. Both short and long-term follow-up are needed.

Sleep Disturbance in Orofacial Pain Patients: Pain-Related or Emotional Distress?

ABSTRACT Associations between pain, depression, and sleep disturbance have been documented in several chronic pain patient samples. The current study assessed the prevalence and magnitude of sleep disturbance in a sample of 128 orofacial pain patients referred for clinical evaluation and tested linkages between sleep, depression, anxiety, and pain using cross-sectional and longitudinal data. Seventy-seven percent of the patients reported reduced sleep quantity since pain onset. In cross-sectional analyses, reduced sleep quantity was associated with depression and pain. Reduced sleep quality was associated with negative affect. Longitudinally, initial depression and pain predicted sleep at time two and initial pain predicted negative affect. Sleep did not predict pain. Results support the hypothesis that pain, rather than sleep disturbance, increases negative affect across time, whereas negative affect is more a cause of concurrent reduced sleep quality than is pain. The results highlight the importance of assessing for sleep disturbance in orofacial pain patients.

Anxiety sensitivity and catastrophizing: associations with pain and somatization in non-clinical children.

This study examined the relationships among anxiety sensitivity (AS), catastrophizing, somatization and pain in 240 non-clinical children (121 girls; mean age = 12.7 years). Children with pain problems (n = 81; 33.8%) reported greater AS and catastrophizing (ps < .01) relative to children without pain problems. AS but not catastrophizing was significantly associated with current pain. However, both AS and catastrophizing were significantly associated with somatization. AS and catastrophizing represent related but partially distinct cognitive constructs that may be targeted by interventions aimed at alleviating pain and somatization in children.

Complementary Therapies and Childhood Cancer

BACKGROUND The use of complementary and alternative therapies by children with cancer is common. Up to 84% of children have used complementary therapies along with conventional medical treatment for cancer. METHODS We reviewed the PubMed and CINAHL databases for studies published between 1994 and 2004 on the use of complementary and alternative therapies by children with cancer and reports from any publication year through 2004 of clinical trials involving complementary and alternative therapies for children with cancer. RESULTS Fourteen studies were retrieved reporting the results of survey or interview data collected from parents on childrens use of complementary and alternative therapies during or after childhood cancer. Across studies, the use of such therapies ranged from 31% to 84%. Common reasons for using complementary and alternative therapies were to do everything possible for their child, to help with symptom management, and to boost the immune system. Many parents indicated they also hoped to treat or cure the cancer. In most cases, the childs treating physician had not been informed of the childs use of complementary and alternative therapies. CONCLUSIONS Use of complementary therapies by children with cancer is common, although methodological variations limit the ability to compare results across studies. Treating physicians often do not know the child is using complementary therapies in addition to medical treatments. The scientific evidence is limited regarding the effects and mechanisms of action of complementary or alternative therapies, but research is being conducted on these topics.