Mark A. Slater

Prevalence, onset, and risk of psychiatric disorders in men with chronic low back pain: a controlled study

&NA; This study used structured diagnostic interviews and DSM‐III criteria to assess lifetime prevalence and pre‐morbid risk of psychiatric disorder in a sample of men with long‐standing chronic back pain (CLPB) attending a primary care clinic. A control group of age and demographically matched men without history of back pain was also studied. Compared to controls, men with CLBP had significantly higher lifetime rates of major depression (32% vs. 16%), alcohol use disorder (64.9% vs. 38.8%), and a major anxiety disorder (30.9% vs. 14.3%). Almost all CLBP men ever experiencing a mood disorder reported recurrent, not single, episodes. The 6 month point prevalence of major depression, but not other disorders, was also significantly elevated for men with CLBP. In CLBP, the first episode of major depression generally (58.1%) followed pain onset. While the initial major depressive episode usually commenced within the first 2 years of established pain, late onset mood disorder was also common. By comparison in most cases (81%) onset of alcohol use disorders considerably preceded pain. When an age‐matching procedure was used to gauge relative vulnerability to psychiatric illness in patients and controls, CLBP patients had significantly higher pre‐pain rates of alcohol use disorder but not depression. After age of pain onset, CLBP subjects had over 9 times the risk of developing major depression, but had similar rates of developing alcoholism. We conclude that (1) alcohol use disorders rather than depression may increase risk of developing CLBP, and (2) risk of new onset and recurrent major depression remains high for men throughout their pain career. This suggests that psychological adaptation to long‐standing pain may be less successful than previously thought, especially with regard to recurrent mood disorder.

A placebo-controlled randomized clinical trial of nortriptyline for chronic low back pain

&NA; To assess the efficacy of nortriptyline, a tricyclic antidepressant, as an analgesic in chronic back pain without depression, we conducted a randomized, double‐blind, placebo‐controlled, 8‐week trial in 78 men recruited from primary care and general orthopedic settings, who had chronic low back pain (pain at T‐6 or below on a daily basis for 6 months or longer). Of these 57 completed the trial; of the 21 who did not complete, four were withdrawn because of adverse effects. The intervention consisted of inert placebo or nortriptyline titrated to within the therapeutic range for treating major depression (50–150 ng/ml). The main outcome endpoints were pain (Descriptor Differential Scale), disability (Sickness Impact Profile), health‐related quality of life (Quality of Well‐Being Scale), mood (Beck Depression Inventory, Spielberger State Anxiety Inventory, Hamilton Anxiety/Depression Rating Scales), and physician rated outcome (Clinical Global Impression). Reduction in pain intensity scores was significantly greater for participants randomized to nortriptyline (difference in mean change 1.68, 95% −0.001, CI −3.36, P=0.050), with a reduction of pain by 22% compared to 9% on placebo. Reduction in disability marginally favored nortriptyline (P=0.055), but health‐related quality of life, mood, and physician ratings of overall outcome did not differ significantly between treatments. Subgroup analyses of study completers supported the intent‐to‐treat analysis. Also, completers with radicular pain on nortriptyline (n=5) had significantly (P<0.05) better analgesia and overall outcome than did those on placebo (n=6). The results suggest noradrenergic mechanisms are relevant to analgesia in back pain. This modest reduction in pain intensity suggests that physicians should carefully weigh the risks and benefits of nortriptyline in chronic back pain without depression.

Subjective sleep disturbance in chronic back pain

Although disturbed sleep is thought to be common in patients with chronic low back pain, little data systematically address this issue. We administered a self-report inventory of sleep performance to an unselected sample of chronic low back pain patients (n= 51) attending a general orthopedic clinic. Approximately 50% (n= 26) of the group experienced poor sleep. Self-reported dissatisfaction with sleep was more strongly associated with more depressed mood and with shorter pain chronicity than with medical evidence of orthopedic disease. Patients with high pain intensity reported significantly less sleep time, more delayed sleep onset, and more nighttime awakenings than did patients with low pain intensity. Overnight polysomnography in a subsample of seven depressed and nondepressed patients with poor sleep revealed abnormalities in a proportion of these subjects, including reduced total sleep time, decreased or absent Stage 3 and 4 sleep, shortened time to onset of rapid eye movement sleep, and periodic leg movements in sleep. Sleep complaints appear to be common in back pain patients and may reflect diverse sleep anomalies. The pathophysiology of these disturbances may be related to pain complaint, affective distress, or independent sleep disorders.

Effects of noradrenergic and serotonergic antidepressants on chronic low back pain intensity.

To understand the relative efficacy of noradrenergic and serotonergic antidepressants as analgesics in chronic back pain without depression, we conducted a randomized, double-blind, placebo-control head-to-head comparison of maprotiline (a norepinephrine reuptake blocker) and paroxetine (a serotonin reuptake blocker) in 103 patients with chronic low back pain. Of these 74 completed the trial; of the 29 who did not complete, 19 were withdrawn because of adverse effects. The intervention consisted of an 8-week course of maprotiline (up to 150 mg daily) or paroxetine (up to 30 mg daily) or an active placebo, diphenhydramine hydrochloride (up to 37.5 mg daily). Patients were excluded for current major depression. Reduction in pain intensity (Descriptor Differential Scale scores) was significantly greater for study completers randomized to maprotiline compared to placebo (P=0.023), and to paroxetine (P=0.013), with a reduction of pain by 45% compared to 27% on placebo and 26% on paroxetine. These results suggest that at standard dosages noradrenergic agents may provide more effective analgesia in back pain than do selective serotonergic reuptake inhibitors.

The contribution of job satisfaction to the transition from acute to chronic low back pain

OBJECTIVE To determine the extent to which job satisfaction predicts pain, psychological distress, and disability 6 months after an initial episode of low back pain (LBP). DESIGN A longitudinal design was used to follow an inception cohort experiencing first-episode low back pain with assessment at 2 and 6 months after pain onset. SETTING Urban medical center outpatient orthopedic clinic. PATIENTS The consecutive sample was comprised of 82 men with initial-onset acute LBP (T6 or below, daily pain for 6 to 10 weeks). INTERVENTION Usual orthopedic care. MAIN OUTCOME MEASURES The primary study outcomes were pain (Descriptor Differential Scale, Visual Analog Scales); disability (Sickness Impact Profile, Quality of Well-Being); and psychological distress (Beck Depression Inventory, Hamilton Rating Scale for Depression, Automatic Thoughts Questionnaire); predictor variables were orthopedic impairment (Waddell Physical Impairment Index) and job satisfaction (Job Descriptive Index, Work APGAR). RESULTS Measures of job satisfaction, pain, disability, and psychological distress at baseline and 6 months after pain onset were separately reduced into factors using principle components factor analysis. In hierarchical multiple regression analyses, baseline job satisfaction significantly predicted variance in outcome scores at 6 months after pain onset, beyond the variance explained by control factors (demographics; baseline pain, mood, and disability; orthopedic impairment). Zero-order correlations between job satisfaction and orthopedic impairment were small and nonsignificant, suggesting that these two variables act independently in predicting outcome. Although type of work performed (desk work or work requiring light, moderate, or heavy lifting) and social position were correlated with job satisfaction at baseline, neither contributed to the prediction of outcome at 6 months. CONCLUSIONS Satisfaction with ones job may protect against development of chronic pain and disability after acute onset back pain and, alternatively, dissatisfaction may heighten risk of chronicity. Vocational factors should be considered in the rehabilitation of acute back injury.

One-year follow-up of first onset low back pain

&NA; Efforts to examine the process and risk of developing chronic back pain have relied generally upon retrospective study of individuals with already established pain. In an alternative approach to understanding the clinical course and evolution of low back disorders, a cohort of 76 men experiencing their first episode of back pain was assessed prospectively at 2, 6 and 12 months following pain onset. Standard measures of pain (Descriptor Differential Scale: DDS), disability (Sickness Impact Profile: SIP), and distress (Beck Depression Inventory: BDI) were employed to classify the sample into five groups: Resolved, Pain Only, Disability/Distress Only, Pain and Mild Disability/Distress, and Clinical Range. At both 6 and 12 months post pain onset, most (78%, 72% respectively) of the sample continued to experience pain. Many also experienced marked disability at 6 months (26%) and 12 months (14%). At 12 months, no participants had worsened relative to the 2‐month baseline. Doubly multivariate analyses of variance (MANOVAs) were employed to compare baseline groups (Pain Only, Pain and Mild Disability/Distress, Clinical Range) on the DDS, SIP, and BDI across time. The group by time interaction from 2 through 12 months was reliable, with greatest change occurring in the Clinical Range group in disability and distress; interestingly, the decrease in pain was comparable among all groups. Follow‐up tests across measures demonstrated greater change in the early (2–6‐month) interval and relative stability in the later (6–12‐month) interval. Comparison of those classified as ‘improvers’ with those who did not improve from 2 to 12 months showed similar findings. The clinical course of first onset back pain may be prolonged for many patients, and involves a continuum of related disability and distress. Individuals at risk for marked symptoms 1 year after an initial episode of back pain can be identified early, and prompt treatment might reduce the risk of pain chronicity.

Depression in spouses of chronic pain patients : the role of patient pain and anger, and marital satisfaction

&NA; Although several studies have shown that spouses of chronic pain patients may experience clinically significant depressive symptoms few studies have comprehensively examined the role of both patient and spouse‐related factors in the development and maintenance of this emotional distress. Twenty‐nine married male chronic benign low back pain patients and their spouses were recruited in order to examine the role of patient, spouse, and marital factors in spouse depressive symptomatology. The results indicated that 28% percent of the spouses in the sample reported significantly depressed mood. A 2‐stage regression analysis was employed that revealed 3 significant predictors of spouses depressed mood, namely patients average pain, patients reported levels of anger and hostility, and the spouses level of marital satisfaction. These findings are discussed in terms of their implications for clinical interventions for pain patients and their families.

Coping activities in chronic low back pain: relationship with depression

&NA; To help clarify the nature of coping activities in chronic pain, this study compared how depressed (n = 37) and non‐depressed (n = 40) chronic low back pain (CLBP) patients attempted to cope with pain‐specific and general non‐pain life Stressors, relative to matched healthy control subjects (n = 40). We hypothesized that depressed mood, rather than pain alone, would account for differences in coping activities between groups. Specifically, we expected that depressed CLBP patients would report a greater proportion of passive and avoidant coping responses and less active problem solving coping attempts than non‐depressed patients and controls. Results indicated that depressed CLBP patients reported more passive‐avoidant coping activities than did non‐depressed CLBP patients and controls, whereas coping responses were similar for non‐depressed CLBP patients and controls. Additionally, subjects across groups tended to report more passive‐avoidant coping in response to the specific back pain Stressor (i.e., exacerbation of back pain during activity) than to other life Stressors. Finally, the magnitude of reported differences in coping attempts across groups varied as a function of the type of Stressor (i.e., specific back pain Stressor vs. general stressful life events), particularly with regard to a disinclination to seek social support in response to the back pain exacerbation. We conclude that: (1) chronic back pain patients may employ different coping activities when attempting to manage pain exacerbations than when confronting more general life Stressors, and (2) an increased rate of passive‐avoidant coping responses (relative to matched healthy controls) is associated with the combination of CLBP and concurrent depressed mood, rather than with CLBP alone. These results suggest that although some patients may selectively employ passive‐avoidant coping activities in response to pain exacerbations, an over‐reliance on passive‐avoidant coping activities is not characteristic of all CLBP patients but is more likely a function of depressed mood.

An empirical evaluation of multidimensional clinical outcome in chronic low back pain patients.

&NA; Individuals with persisting pain often present a constellation of symptoms that includes pain, health‐related impairment and dysphoric mood. It is now widely accepted that comprehensive assessment must address each of these dimensions. Despite recognition of the value of multidimensional assessment, no empirical efforts have validated the construct of a multidimensional clinical outcome presentation based on the dimensions of pain, impairment and dysphoric mood. We employed cluster analytic procedures on standard measures of pain, impairment and depression in chronic low back pain (CLBP) patients (n = 96) attending a general orthopedic clinic in order to empirically characterize multidimensional clinical outcomes. Results indicated that 3 groups could be identified reliably:‘Chronic Pain Syndrome’ (n = 25; high levels of pain, impairment and depression),‘Positive Adaptation to Pain’ (n = 24; high levels of pain with low levels of impairment and depression)‘Good Pain Control’ (n = 47; low levels of pain, impairment and depression). The reliability of this cluster solution was supported by several tests of internal consistency. Discriminability of the clusters was examined across both the outcome measures themselves and several additional independent variables. The cluster solution was then crossvalidated in an independent sample of pain clinic CLBP patients (n = 180) to test its generalizability. Finally the stability of the cluster dimensions over time was tested by re‐assessing 36 CLBP patients 6 months after they initially were characterized into 1 of the 3 outcome groups on the same measures. MANOVA results indicated that the outcome groups were differentiated statistically across assessments. The multiple outcome measures did not change significantly across time, nor did the outcome groups change differentially across time on these measures. We conclude that the outcome dimensions of pain, impairment and depression are relatively stable phenomena that differentially describe CLBP patients.

Psychosocial factors discriminate multidimensional clinical groups of chronic low back pain patients

&NA; Previous studies have empirically defined clinical subgroups of chronic low back pain (CLBP) patients, based on differing patterns of pain, disability and emotional distress. Because these identified groups generally are comparable in terms of physical and demographic variables, variation in functional status cannot be adequately explained by medical or social factors. In the present study we evaluated whether other psychosocial factors (stress, coping attempts, and satisfaction with social supports) might differentiate the observed groups. A discriminant function analysis indicated that ratings of life adversity, coping, and social support statistically differentiate clinical groups of CLBP patients. Patients categorized as chronic pain syndrome (i.e., high levels of pain, disability and depression) reported greater life adversity, more reliance on passive/avoidant coping strategies, and less satisfaction with social support networks. Patients categorized as having good pain control (i.e., low levels of pain, disability and depression) reported less life adversity, less reliance on passive/avoidant coping strategies, and more satisfaction with social support networks. Finally, a mixed picture of less life adversity, but more reliance on passive/avoidant coping strategies and more satisfactory social support networks was reported by patients categorized in the positive adaptation to pain group (i.e., high levels of pain, but relatively low levels of disability and depression). These findings suggest that psychosocial factors may be important and complex correlates of multidimensional clinical presentations of CLBP. Psychosocial factors may also offer an avenue for intervention across 3 key dimensions of CLBP.