KLAUS KUCH, M.D.I, BRIAN Cox, M.A.2, RAMON 1. EVANS, M.D.3, PETER C. WATSON, M.D.4 AND CONSTANTINE BUBELA, M.D.5. In 61 patients with ...
To What Extent Do Anxiety and Depression Interact with Chronic Pain?* KLAUS KUCH, M.D. I, BRIAN Cox, M.A. 2, RAMON 1. EVANS, M.D. 3, PETER C. WATSON, M.D.4 AND CONSTANTINE BUBELA, M.D. 5
In 61 patients with generalized musculoskeletal pain, severity ofanxiety and depression correlated significantly with self-reported impact ofillness and physician-rated disability. Depression was significantly associated with pain-frequency, whereas anxiety was unrelated. Depressed mood was more closely tied to patients' ability to function than to their experience ofpain.
T
he management of chronic pain without definitive organic pathology is of growing interest in psychiatry. Complaints about chronic pain appear to be fairly common in patients with panic disorder (1). Conversely, anxiety disorder (2,3) and depression (4-6) are fairly common in patients with chronic pain. Observations of concurrent psychiatric and chronic pain disorders may raise expectations from psychiatric treatment, not only in regard to psychiatric symptoms but also in regard to pain. Relief from psychiatric symptoms does not predict relief from pain, and the nature of the association between anxiety-depression and pain remains unclear. The presence of dual diagnoses may indicate no more than comorbidity in the sense that patients suffer from two largely independent disorders; pain and mood disturbance. Alternatively, there may be some interdependence between severity of mood disturbance and severity of pain. Any interdependence between mood and pain is of interest to those involved in rehabilitation and prescribing psychiatric and analgesic medications (7). Equally interesting would be any correlation between mood and disability, because mood could be a predictor of a patient's ability to cope with chronic pain. To date, the correlation between mood and pain has not been studied in detail. We investigated the correlations between mood using two measures of self-reported pain, the
*Manuscript received July 1991, revised December 1991. IAssistant Professor, Department of Psychiatry and Anaesthesia, University of Toronto, Toronto, Ontario. 2Doctoral Fellow, Department of Psychology, York University, Toronto, Ontario. 3Associate Professor, Department of Surgery, Medicine and Anaesthesia, University of Toronto, Toronto, Ontario. 4Assistant Professor, Department of Neurology, University of Toronto, Toronto, Ontario. 5Lecturer, Department of Anaesthesia, University of Toronto, Toronto, Ontario. Address reprintrequeststo: Dr. Klaus Kuch, Smyth Pain Clinic, 3 Bell Wing, Toronto Genereal Hospital, 200 Elizabeth Street, Toronto, Ontario M5G 2C4
Can. J. Psychiatry Vol. 38, February 1993
self-reported impact of the illness and physician-rated disability. We chose a convenience sample with generalized myofascial pain that met IASP diagnostic criteria for fibromyalgia (8).
Method Sixty-one subjects were enroled sequentially from referrals by medical practitioners to a multidisciplinary pain clinic. They were 26 males and 35 females with a mean age of 44 years (SD = 10.56, range = 20 to 76). In 33 patients, the onset of pain was preceded by a motor vehicle accident. All had been in pain for more than one year (mean = 62.23 months, SD = 51.32) and had not experienced a remission. All subjects underwent a physical examination by an experienced physician of the clinic to rule out contributory anatomical abnormalities and to establish the diagnosis of fibromyalgia (8). A pain drawing from the McGill Pain Questionnaire (9) was used to confirm generalization of pain. Generalization of pain was considered relevant to the homogeneity of the sample because generalization is associated with somatization and depression (10). A history of traffic accidents was not considered to be a factor causing heterogeneity in regard to sleep pathology (11). Self-reported pain was rated for the preceding week; pain intensity was rated on a zero to eight Likert scale, and pain frequency on a zero to 100% sliding scale to reflect the percentage of waking hours spent in pain. Self-rated impact of illness (insomnia, activity change at home, work, recreation and global) was assessed by the Sickness Impact Profile (SIP), a behavioural questionnaire with demonstrated reliability and validity for global and subscales (12-15). Measures of psychopathology were rated by one psychiatrist. Disability was rated on the Sheehan Scale (zero to eight) and severity of anxiety and depression on the Hamilton scales (16). DSM-III-R diagnoses were determined using the Structured Clinical Interview (SCID) (17).
Results Sample Characteristics Complete pain ratings were obtained from 56 patients (91.8%), completed Hamilton scales from 55 patients (90.2%) and complete SIP questionnaires from 52 patients (85.2%). In the 61 patients with pain, the most common diagnoses were major affective disorder (26.4%) and accident-related phobia (27.9%). Phobias were three times more 36
February, 1993
- - -Variable -----
37
ANXIETY AND DEPRESSION INTERACfING WITH CHRONIC PAIN
Table I Correlations Between Pain, Anxiety, Depression and Disability Sickness Impact Sickness Hamilton Rating Profile Impact Profile Pain Scale for Anxiety Frequency (sleep/rest) (global score) 0.73* 0.35t 0.32+ 0.54*
Hamilton Rating Scale for Depression Hamilton Rating Scale for Anxiety Sickness Impact Profile (sleep/rest) Sickness Impact profile (global score) Pain frequency Pain intensity 'p < 0.001; tp < 0.01; tp < 0.05
0.06
common in patients with a history of traffic accidents than in the remaining sample. Psychiatric diagnoses and their relationship to psychological trauma are discussed elsewhere (18). The mean pain intensity was 5.45 (SD = 0.88) on a scale of zero to eight and the mean percentage of pain frequency was 79.0%. Mean physician-rated disability was 4.74 (SD = 1.62) on a scale of zero to eight. On the SIP, the mean global dysfunction score was 44.81 (SD = 20.17) and the mean of the SIP subscale sleep/rest was 41.21, SD = 27.2. The mean score on the Hamilton Rating Scale for Depression (HRSD) was 17.68 (SD = 6.83) and the mean score on the Hamilton Rating Scale for Anxiety was 18.67 (SD = 6.96). There were no significant gender differences on any of the variables. There were no significant differences between the survivors of motor vehicle accidents and the other subjects on the frequency and the severity of pain. Table I presents the correlations between the main variables and corresponding levels of significance (two-tailed). The largest correlations were between physician-rated depression, physician-rated disability and patient-rated impact of illness. Pain was correlated significantly with physician-rated disability but not with patient-rated impact of illness. A median split procedure showed that the group who scored highest on the depression scale tended to score higher on pain frequency (t = 1.93, df =50, p < 0.06), SIP-sleep/rest (t = 1.99, df =44, P < 0.06) and SIP-recreation (t = 1.75, df = 44, P < 0.09) than those who scored lower on the depression scale.
Discussion The severity of depression correlated significantly with patient-rated global sickness impact and with physician-rated disability. The correlations accounted for approximately 25% of the variance in these measures. Severity of anxiety also correlated significantly with patient-rated sickness impact and physician-rated disability. However, the relationship be-
Pain Intensity 0.22
Physician Rated Disability 0.49*
0.50*
0.25
0.14
0.3M
0.60*
0.01
0.03
0.11
0.14
0.08
0.38t
0.31+
0.33t 0.30+
tween degree of mood disturbance and pain was weak. Depression was related to pain frequency and unrelated to pain intensity. Anxiety was unrelated to both measures of pain. Mood was therefore more closely tied to patients' ability to cope with pain than to pain itself. This finding is consistent with the findings of a study that observed more catastrophic cognitions in depressed than in non depressed subjects with chronic low back pain (19). One previous longitudinal study examined the correlation between self-rated pain/anxiety, pain/depression, pain/downtime and depression/downtime in a sample of patients with unspecified chronic pain disorder. Most patients in this study reported significant correlations among their visual analogue scores, but considerable variations occurred among patients (20). This heterogeneity cautions against generalizing from one chronic pain sample to others. It may be useful to replicate the relationships observed in samples with other types of chronic pain disorder. Fordyce (21) distinguishes pain and noxiception from suffering. He emphasizes the affective or emotional nature of suffering as part of the chronic pain experience. In keeping with his construct, we propose that measures of anxiety and depression capture some aspects of suffering and that they are clinically useful in the management of patients suffering from chronic pain.
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Resume Sur 61 patients souffrant de douleur myofasciale generalisee, les indices Hamilton de l'anxiete et de la depression correspondent significativement avec les raports de l'impact de la maladie et les indices de tinfirmite. Les indices Hamilton de l'anxieteldepression et l'infirmite est plus proche que l' association entre l'anxieteldepression et la douleur.
