Edwin F. Kremer

Measurement of pain: patient preference does not confound pain measurement.

Abstract Chronic pain patients reported pain intensity on each of 3 pain intensity scales, the visual analog, numerical and adjectival scales, and then ranked the scales in order of perceived best communication of pain intensity. All patients were able to complete an adjectival scale but 11% were unable to complete a visual analog scale and 2% failed at a numeric scale. The intensity of the pain ratings on the 3 scales were significantly correlated and there were no reliable differences in reported intensity as a function of preference. Pain intensity was reliably higher on each scale for depressed‐anxious patients as compared to non‐depressed/non‐anxious patients. Patients completing all 3 scales indicated a significant preference for the adjectival scale but the basis for this preference did not appear related to sex, etiology of pain, affective variables nor selected psychological variables. These data indicate that pain scale preference does not influence pain intensity report. Nevertheless, there are some clinical situations in which a numeric scale is likely to yield a better measure of pain intensity.

Pain measurement: construct validity of the affective dimension of the McGill Pain Questionnaire with chronic benign pain patients.

Abstract The research reported here used a population of chronic benign pain patients and examined the relationship between scores in the affective dimension of the McGill Pain Questionnaire and independent measures of affect and infirmity. The data indicated that patients who reported high affective dimensional scores were significantly more depressed and anxious and somatized more than patients who reported low affective scores. Similarly, these high affective patients reported significantly greater perceived infirmity secondary to their pain. These results suggest that the affective dimension score of the McGill Pain Questionnaire can serve as a useful index of the overall affective status of pain patients and given this interpretation the dimension has good construct validity.

Pain measurement: The affective dimensional measure of the McGill pain questionnaire with a cancer pain population☆

Abstract Two experiments used the McGill Pain Questionnaire (MPQ) to examine the affective dimension of pain in patients whose pain was secondary to malignancy. In experiment I, segregating groups of cancer patients on the basis of extreme scores (high versus low) on the MPQ failed to produce segregation on independent measures of affect and infirmity. This outcome contrasts with earlier work with chronic benign pain patients. Experiment II compared cancer pain patients matched with benign pain patients on intensity of pain report on the affective dimension of the MPQ. Cancer pain patients reported a reliably higher affective loading to their pain. These data suggest that cancer pain patients employ different criteria than benign pain patients in selecting affective pain descriptors. Possible explanations for this difference are discussed.

Plasma measures of beta-endorphin/beta-lipotropin-like immunoreactivity in chronic pain syndrome and psychiatric subjects

This study compared basal concentrations of plasma beta-endorphin/beta-lipotropin-like immunoreactivity and dexamethasone suppression of cortisol in seven chronic pain patients, seven psychiatric disorder patients, and seven normal volunteers. Pain patients and psychiatric patients showed significantly higher basal concentrations of beta-endorphin/beta-lipotropin-like immunoreactivity compared to normal volunteers. Pain patients also had significantly higher beta-endorphin/beta-lipotropin-like immunoreactivity than psychiatric patients, even though there was no significant difference in severity of depressive symptomatology as assessed by Beck and Hamilton scores. Resistance to dexamethasone occurred in 57% of pain patients. These results may indicate that biological markers for depression occur in populations of chronic pain patients, or may reflect levels of central nervous system arousal in response to stress, pain, or nonaffective phenomena.

The language of pain: Affective descriptors of pain are a better predictor of psychological disturbance than pattern of sensory and affective descriptors

Abstract The language used by chronic benign pain patients to characterize their pain complaint was analyzed to determine the best predictor of psychiatric disturbance. Using the 78 adjectives provided by the McGill Pain Questionnaire, the number of affective descriptors used was the best predictor of psychiatric disturbance. Addition of sensory descriptors either to augment the total number of descriptors used (magnitude) or as a pattern of sensory > affective or sensory < affective failed to increase predictive strength.

MMPI subgroups and affective disorder in chronic pain patients.

Patients with chronic pain syndromes are commonly depressed. Chronic pain populations also contain distinct subgroups of personality profiles as defined by the MMPI. To assess the relevance of personality subtype to affective disorder we determined the relationship of psychiatric diagnoses defined by Research Diagnostic Criteria (RDC) to MMPI subgroups in a sample of hospitalized patients with predominantly chronic low back pain. RDC psychiatric diagnoses for the sample were major depression (44.2%), minor depression (19.2%), other psychiatric disorder (13.5%), and no mental disorder (21.6%). Patients satisfying RDC criteria for major depression were significantly associated with discrete MMPI personality subtypes. No other psychiatric diagnoses were significantly associated with distinct personality subgroups. No relationship was observed between personality profile and presence of demonstrable organic etiology for pain. These findings indicate that behavioral and pharmacological interventions directed at depression as well as pain are important in the treatment of chronic pain populations, especially in selected subgroups.

Basal and post-dexamethasone cortisol and prolactin concentrations in depressed and non-depressed patients with chronic pain syndromes

&NA; To assess the behavior of two putative neuroendocrine markers of depression in chronic pain, the authors determined plasma cortisol and prolactin concentrations before and after dexamethasone in 52 hospitalized male chronic pain patients. Their psychiatric diagnoses by Research Diagnostic Criteria (RDC) were: major depression (N = 24; 44.2%), minor depression (N = 10; 19.2%), another RDC diagnosis (N = 7; 13.5%) and not mentally ill (N = 12; 21.6%). Failure to suppress cortisol after dexamethasone (a positive DST) occurred in 43.5% of those with major depression, 20% of those with minor depression, 42.8% of those with other psychiatric diagnoses and in 8.3% of patients without a psychiatric disorder. The frequency of non‐suppression was significantly different only for patients with major depression compared to those without diagnosable psychiatric disorder. Mean basal cortisol concentrations at 08.00, 16.00 and 23.00 h did not differ among psychiatric diagnostic groups of pain patients, or between these groups and healthy volunteers. Levels of prolactin, but not cortisol, were significantly correlated with the severity of mood disturbances. These findings suggest strategies using multiple endocrine markers to distinguish pain from depression should be explored.

Spousal perpetuation of chronic pain behavior

The literature reviewed here demonstrates that spousal response to pain display can reinforce and thereby perpetuate the patients pain behavior. Relationships characterized as “sick-role homeostatis” reflect a nexus of behavioral contingencies which are highly resistant to treatment. Though such relationships could developde novo subsequent to accident or injury, modeling and familial effects in chronic pain suggest a rich personal and family history of chronic pain learning experiences. Spousal reinforcement of pain behavior is greater in satisfied relationships and tends to involve contingent attention and caring rather than assistance or taking over tasks and chores. As the vast majority of pain patients and spouses report being satisfied with their marriages, spousal involvement in chronic pain treatment is critical.

Neuroendocrine responses in psychiatric and pain patients with major depression

Basal and postdexamethasone concentrations of cortisol and prolactin were studied in three groups of male patients: chronic pain patients with no psychiatric diagnosis (n = 12), chronic pain patients with coexisting major depression by Research Diagnostic Criteria (RDC) (n = 24), and pain-free psychiatric patients meeting RDC criteria for major depression (n = 28). Basal cortisol concentrations were significantly higher in pain-major depression and psychiatric-major depression patients compared to pain patients without psychiatric illness. The frequency of cortisol nonsuppression after dexamethasone was significantly greater in pain patients with major depression (41.7%) compared to pain patients without psychiatric disorder (8.3%), and was comparable to that of psychiatric patients (21.4%). Prolactin concentrations, but not cortisol levels, were significantly correlated with observer-rated severity of depression in pain patients. These findings suggest that cortisol and prolactin abnormalities in chronic pain may be related to psychiatric disorder rather than to pain per se, at least in male patients, and may indicate a role for cholinergic mechanisms in the interface of pain and depression.

Pain language: Affect

Pain language was examined by performing a principal components factor analysis on pain descriptors selected from the McGill Pain Questionnaire by 126 chronic pain patients. Six factors emerged with the greatest variance accounted for by an affective dimension (Factor I). Location of patients in space defined by these factors failed to differentiate medical diagnostic categories or pain intensity but revealed good differentiation on affective distress secondary to pain. Results demonstrate that affective distress is a potent variable in pain language and likely confounds efforts to relate language to medical diagnostic categories.