Changes in perceived pain severity following interdisciplinary treatment for chronic pain.

BACKGROUND: There is good support for the effectiveness of interdisciplinary chronic pain management programs in improving functional outcomes; however, relatively little is known about patients who report deterioration following participation in such programs. OBJECTIVES: The present retrospective study investigated patients' reports of increased pain severity during participation in a cognitive-behaviourally oriented, outpatient treatment for chronic pain. METHODS: Participants (n=280) completed a four-week, group-based, interdisciplinary chronic pain self-management program at a rehabilitation hospital. They completed pre- and post-treatment questionnaires, which included global change ratings of pain severity and clinically-relevant measures, including pain intensity ratings, functional limitations, pain catastrophizing and self-efficacy. RESULTS: Statistically significant pre-post improvements were observed for all study variables. Almost all patients reported global improvement overall. Nevertheless, a subset of patients (n=99) reported increased pain severity on global ratings. These individuals were characterized by lower self-efficacy at baseline. CONCLUSIONS: Participants endorsed significant pre- and post-treatment improvements in all domains. Nevertheless, some participants reported deterioration. The findings shed light on variables associated with negative treatment outcomes and have practical applications for interdisciplinary chronic pain management programs.

Psychometric properties of the Beck Depression Inventory--second edition (BDI-II) in individuals with chronic pain.

Given the high prevalence of depression in individuals with chronic pain and the negative outcomes associated with such comorbidity, the importance of assessing depressive symptoms is widely acknowledged by chronic pain specialists. The BDI-II is a commonly employed measure of depressive symptomatology at pain centres; however, little is known about its psychometric properties in this population. This study evaluated factorial validity, internal consistency, and gender invariance of the BDI-II in 481 patients with chronic pain. Four competing models of the BDI-II factor structure were examined and confirmatory factor analysis supported the conceptualization of depression as a singular latent construct, within a hierarchical factor structure consisting of three first-order factors--Negative Attitude, Performance Difficulty, and Somatic Elements. Factor structure, item-total correlations, and correlations between subscale means and subjective pain experience support the inclusion of somatic items despite concerns regarding their overlap with pain symptoms. Internal consistency was good. Mean total scores were in the moderately severe range. Given the evidence of partial measurement invariance, an examination of mean gender differences was warranted. In contrast to the general population, the average scores of women and men were similar. Overall, results support the construct validity and internal consistency of the BDI-II for assessing depressive symptoms in both women and men with chronic pain. Results support the appropriateness of computing a total score and/or subscale scores. These results impact chronic pain researchers and clinicians, particularly given current trends toward empirically supported assessment.

Testing factorial validity and gender invariance of the pain catastrophizing scale.

Recent research has indicated that the Pain Catastrophizing Scale (PCS) is a reliable measure that taps three dimensions of a singular construct. Gender differences have been found consistently in catastrophizing, with women reporting significantly higher scores than men on the PCS. This study was designed to cross-validate the factor structure of the PCS, independently for men and women, through second-order confirmatory factor analysis. Results indicate that the second-order models provide a good fit to the data. The conceptualization of catastrophizing as a singular latent construct, within a hierarchical factorial structure that consists of three first-order factors--rumination, magnification, and helplessness, was supported for both men and women. The second research objective was to test the two models for gender equivalence. Results indicate that all constraints held across gender. Together, these findings support the psychometric soundness of the PCS and indicate that the gender differences found are not due to an inadequate fit of the measurement or structural model.

Sleep in depressed and nondepressed participants with chronic low back pain: electroencephalographic and behaviour findings.

STUDY OBJECTIVES: To study the nature of sleep disturbance in depressed and nondepressed patients with chronic low back pain (CLBP). DESIGN: A controlled, consecutive 4-night polysomnographic study. PATIENTS: Participants were screened (psychologic, psychiatric, and physical) to determine their study group, and 21 participants (CLBP: 4 depressed, 6 nondepressed and 11 controls) were studied. MEASUREMENTS AND RESULTS: On all nights, standard polysomnographic sleep measures as well as midline occipital and frontal electroencephalography and respiration were recorded on a Grass Model 7 polygraph. Pain, sleep quality, and depression were also measured. Participants with CLBP reported significant levels of pain and sleep disturbance as compared to controls, but all groups had equivalent amounts of sleep and comparable sleep architecture. The electroencephalographic power spectral analyses revealed significant differences, with controls having more sigma across sites, more low beta activity occipitally and frontally than nondepressed patients with CLBP, and more occipital sigma and less high beta activity than depressed participants. Between pain subgroups, the depressed participants showed more occipital delta, more occipital and central alpha, and more high beta activity across all sites than did the nondepressed participants. CONCLUSIONS: Lower sigma power in participants with CLBP suggests less-effective sensorimotor gating that may contribute to poor sleep quality. Pain subgroup differences underscore the need to consider the influence of depression in the evaluation of sleep in clinical populations. This study controlled for many factors other than pain that may contribute to the sleep complaints in this population. Consequently, the absence of signs of major sleep disturbance must not be interpreted as evidence of a lack of a true sleep problem in CLBP but more likely reflects control of these factors as well as the difficulty in measuring sleep quality.

Major depression and insomnia in chronic pain.

OBJECTIVES: Insomnia and depression are common problems for people with chronic pain, and previous research has found that each is correlated with measures of pain and disability. The goal of this study was to examine the combined impact of major depression and insomnia on individuals with chronic pain. METHODS: The participants were patients with chronic musculoskeletal pain who underwent evaluation at an interdisciplinary treatment center. On the basis of semistructured interviews, participants were classified in three groups depending on whether they: (1) met criteria for major depression with insomnia (n = 38); (2) had insomnia without major depression (n = 58); or (3) had neither insomnia nor major depression (n = 47). The groups were then compared on self-report measures that included the McGill Pain Questionnaire, the Beck Depression Inventory, and the Multidimensional Pain Inventory. RESULTS: Participants with major depression and insomnia reported the most difficulty on measures of affective distress, life control, interference, and pain severity, although the insomniac patients without major depression also had elevated scores on some measures. In regression analyses, insomnia severity ratings did not contribute uniquely to the prediction of psychosocial problems when depression was controlled, but they did contribute to the prediction of pain severity. CONCLUSIONS: These results suggest that patients with chronic pain and concurrent major depression and insomnia report the highest levels of pain-related impairment, but insomnia in the absence of major depression is also associated with increased pain and distress.

Alternative diagnostic criteria for major depressive disorder in patients with chronic pain.

Chronic pain is associated with high rates of major depressive disorder (MDD), but somatic symptoms caused by pain may complicate the diagnosis of MDD. Different methods to address this issue include the adoption of an inclusive approach to diagnosis (i.e. including all symptoms when assessing MDD, regardless of their presumed cause), an etiologic approach (i.e. disregarding symptoms that are caused by medical problems), and a substitutive approach (i.e. replacing somatic symptoms with non-somatic alternatives). In this study, 129 patients with chronic pain (56 men and 73 women) underwent semi-structured interviews addressing 23 individual symptoms of MDD. Detailed probing was undertaken into patients' perceptions of the causes of those symptoms that could potentially be brought on by pain. We found that the prevalence of MDD was highest with the inclusive diagnostic method (35.7%), lowest with an etiologic approach that discounted symptoms based on patient attributions (19.4%), and intermediate with the substitutive method (30.3%). Although some symptoms, such as insomnia, fatigue, and difficulty concentrating, were reported by 34--53% of the patients who did not meet criteria for MDD, they were still more common among those who did (85--94%, P<0.001). Patients who met criteria for MDD with the inclusive method, but who did not meet criteria using the etiologic method, had Beck Depression Inventory scores (M=24.5) that were comparable to those of patients who were consistently classified with MDD across methods (M=25.6). These scores were much higher than those of patients who were consistently classified without MDD (M=13.8, P<0.001). In conclusion, excluding criterion symptoms that patients attribute to pain can reduce the observed prevalence of MDD by about 45%. However, this method introduces a problem of false-negative diagnoses that appears to be more significant than the problem of false positives associated with the inappropriate inclusion of somatic symptoms.

Confirmatory factor analysis of a 4-factor model of chronic pain evaluation.

Extending the earlier work of Mikail et al. (1993), a confirmatory factor analysis (CFA; LISREL VII) of a 4-factor model of pain assessment was tested. This model, comprised of the Beck Depression Inventory (BDI) and 13 subscales of the McGill Pain Questionnaire (MPQ) and the West Haven-Yale Multidimensional Pain Inventory (WHYMPI), adequately accounted for the pain experience with minimal overlap. Subjects were 306 outpatient chronic pain patients seen at a multidisciplinary chronic pain clinic. Subscale scores were subjected to CFA procedures that yielded a well-fitting final model that explained 91% of the covariance in the observed data. This final model was derived through an exploratory post-hoc procedure that allowed for correlated errors among subscales of the same instrument. The 4 factors were identified as Affective Distress, Support, Pain Description, and Functional Capacity. Results supported the hypothesis that the MPQ, WHYMPI and BDI are representative of the multidimensionality of the pain experience with minimal overlap among measures. Theoretical and clinical implications of reducing the overlap among existing measures in the assessment of pain patients are discussed.