Descriptor Differential Scale Research Articles

Efficacy of Low-Dose Amitriptyline for Chronic Low Back Pain

Antidepressants at low dose are commonly prescribed for the management of chronic low back pain and their use is recommended in international clinical guidelines. However, there is no evidence for their efficacy. To examine the efficacy of a low-dose antidepressant compared with an active comparator in reducing pain, disability, and work absence and hindrance in individuals with chronic low back pain. A double-blind, randomized clinical trial with a 6-month follow-up of adults with chronic, nonspecific, low back pain who were recruited through hospital/medical clinics and advertising was carried out. Low-dose amitriptyline (25 mg/d) or an active comparator (benztropine mesylate, 1 mg/d) for 6 months. The primary outcome was pain intensity measured at 3 and 6 months using the visual analog scale and Descriptor Differential Scale. Secondary outcomes included disability assessed using the Roland Morris Disability Questionnaire and work absence and hindrance assessed using the Short Form Health and Labour Questionnaire. Of the 146 randomized participants (90 [61.6%] male; mean [SD] age, 54.8 [13.7] years), 118 (81%) completed 6-month follow-up. Treatment with low-dose amitriptyline did not result in greater pain reduction than the comparator at 6 (adjusted difference, -7.81; 95% CI, -15.7 to 0.10) or 3 months (adjusted difference, -1.05; 95% CI, -7.87 to 5.78), independent of baseline pain. There was no statistically significant difference in disability between the groups at 6 months (adjusted difference, -0.98; 95% CI, -2.42 to 0.46); however, there was a statistically significant improvement in disability for the low-dose amitriptyline group at 3 months (adjusted difference, -1.62; 95% CI, -2.88 to -0.36). There were no differences between the groups in work outcomes at 6 months (adjusted difference, absence: 1.51; 95% CI, 0.43-5.38; hindrance: 0.53; 95% CI, 0.19-1.51), or 3 months (adjusted difference, absence: 0.86; 95% CI, 0.32-2.31; hindrance: 0.78; 95% CI, 0.29-2.08), or in the number of participants who withdrew owing to adverse events (9 [12%] in each group; χ2 = 0.004; P = .95). This trial suggests that amitriptyline may be an effective treatment for chronic low back pain. There were no significant improvements in outcomes at 6 months, but there was a reduction in disability at 3 months, an improvement in pain intensity that was nonsignificant at 6 months, and minimal adverse events reported with a low-dose, modest sample size and active comparator. Although large-scale clinical trials that include dose escalation are needed, it may be worth considering low-dose amitriptyline if the only alternative is an opioid. anzctr.org.au Identifier: ACTRN12612000131853.

A randomized controlled trial of gabapentin for chronic low back pain with and without a radiating component.

Gabapentin is prescribed for analgesia in chronic low back pain, yet there are no controlled trials supporting this practice. This randomized, 2-arm, 12-week, parallel group study compared gabapentin (forced titration up to 3600 mg daily) with inert placebo. The primary efficacy measure was change in pain intensity from baseline to the last week on treatment measured by the Descriptor Differential Scale; the secondary outcome was disability (Oswestry Disability Index). The intention-to-treat analysis comprised 108 randomized patients with chronic back pain (daily pain for ≥6 months) whose pain did (43%) or did not radiate into the lower extremity. Random effects regression models which did not impute missing scores were used to analyze outcome data. Pain intensity decreased significantly over time (P < 0.0001) with subjects on gabapentin or placebo, reporting reductions of about 30% from baseline, but did not differ significantly between groups (P = 0.423). The same results pertained for disability scores. In responder analyses of those who completed 12 weeks (N = 72), the proportion reporting at least 30% or 50% reduction in pain intensity, or at least "Minimal Improvement" on the Physician Clinical Global Impression of Change did not differ significantly between groups. There were no significant differences in analgesia between participants with radiating (n = 46) and nonradiating (n = 62) pain either within or between treatment arms. There was no significant correlation between gabapentin plasma concentration and pain intensity. Gabapentin appears to be ineffective for analgesia in chronic low back pain with or without a radiating component.

Moderate Heat Pain is Less Unpleasant After Brief Intense Eccentric Exercise

Acute exercise can reduce sensitivity to painful stimuli, but the role of eccentric actions in this response is unknown. Research has focused on post-exercise changes in pain intensity and less is known about affective aspects of pain. PURPOSE: The aim was to explore the effects of brief, intense non-dominant arm eccentric exercise on affective and sensory aspects of heat pain sensitivity elicited both in dermatomes of the exercised limb (forearm) and those of a non-exercised limb (lower leg). METHODS: Maximal voluntary concentric contraction strength (MVCCS) of the non-dominant elbow flexors was obtained from ten untrained women who then lowered a dumbbell 18 times with their non-dominant arm. The weight lowering involved three sets of 6 reps at intensities equal to MVCCS. The mean (± SD) absolute weight in each set was18.5 (± 5 lbs), 18.5 (± 5 lbs) and 18.3 (± 5 lbs), respectively. Pain ratings using the intensity and unpleasantness forms of the Descriptor Differential Scale (DDS) were made in response to thermal stimuli applied before and immediately after eccentric exercise. A 30 × 30 mm thermode (TSA-II NeuroSensory Analyzer, Medoc) was used to present heat stimuli to the skin for 2 seconds. Thermal stimuli were applied to a total of 12 unique non-dominant limb sites - six volar forearm (3 medial, 3 lateral) and six posterior lower leg sites. Three randomly ordered temperatures (45, 47, & 49 °C) were applied twice to both leg and arm sites. The criterion used for analysis was the mean of two total DDS intensity and DDS affect scores at each temperature. Six women controls were pre- and post-tested under conditions identical to the treatment group except that no eccentric exercise was performed. RESULTS: Treatment [Eccentric Exercise versus Control] × Time [Pre versus Post] ANOVAs, controlling for arm pain intensity during the MVCCS (0-100 visual analog scale), were not significant for the pain intensity responses at the arm or the leg sites. Significant interactions were found for arm (F1,13=4.714, p=.049) and leg (F1,13=7.066, p=.02) affect ratings at 49 °C. Post-hocs showed lower post-test ratings for exercisers (p <.02). CONCLUSION: Intense, short duration arm eccentric exercise can reduce the unpleasantness of moderate intensity heat stimuli applied to the skin of both an exercised arm and a non-exercised leg.

Delayed Effects Of Mildly Injurious Eccentric Exercise On Thermal Pain Perception

Reduced sensitivity to painful stimuli can occur immediately after exercise, but little is known about whether eccentric exercise resulting in muscle damage and delayed onset inflammation and pain alters perceptions of concomitant noxious stimuli. PURPOSE: To explore the delayed effects of eccentric exercise on affective and sensory aspects of heat pain sensitivity. METHODS: Six women controls were pre- and post-tested under conditions identical to the exercise group except that no eccentric exercise was performed. Maximal voluntary concentric contraction strength (MVCCS) of the non-dominant elbow flexors was obtained from 10 untrained women who then lowered a dumbbell 18 times with their non-dominant arm. The weight lowering involved three sets of 6 reps at intensities equal to MVCCS. The eccentric exercise caused a minor arm muscle injury that was apparent 24 to 48 hours post-exercise as inferred from statistically significant reductions in both maximal isometric force at 90 degrees (-32.7%) and elbow range of motion (-7.9%) as well as increases in arm volume (2.5%) and arm pain intensity ratings (0 to 100 scale) from 0 to 21 (< 40 = mild) in response to performing a dumbbell arm curl with 50% of MVCCS. Pain ratings, using the intensity and unpleasantness forms of the Descriptor Differential Scale (DDS), were made in response to thermal stimuli applied before eccentric exercise and 24- and 48-hours later. A 30 × 30 mm thermode (TSA-II NeuroSensory Analyzer, Medoc) was used to present heat stimuli to the skin for 2 seconds. Thermal stimuli were applied to a total of 12 unique non-dominant limb sites - six volar forearm (3 medial, 3 lateral) and six posterior lower leg sites. Three randomly ordered temperatures (45, 47, & 49 degrees C) were applied twice to both leg and arm sites. RESULTS: Treatment (Eccentric Exercise versus Control) × Time (Pre versus Post [mean of 24- & 48-hour data]) ANOVA showed a significant interaction for arm pain intensity ratings at 49 degrees C (F1,14=5.613, p=.033). One-to-two days after exercise, pain intensity was reduced by 11% and differed from the controls at the post-test by 0.47 standard deviations. CONCLUSION: One to two days after injurious eccentric exercise the perceived intensity of moderately painful heat stimuli applied to the skin in the same dermatome of the exercised muscle is reduced.

Smoked Medicinal Cannabis for Neuropathic Pain in HIV: A Randomized, Crossover Clinical Trial

Despite management with opioids and other pain modifying therapies, neuropathic pain continues to reduce the quality of life and daily functioning in HIV-infected individuals. Cannabinoid receptors in the central and peripheral nervous systems have been shown to modulate pain perception. We conducted a clinical trial to assess the impact of smoked cannabis on neuropathic pain in HIV. This was a phase II, double-blind, placebo-controlled, crossover trial of analgesia with smoked cannabis in HIV-associated distal sensory predominant polyneuropathy (DSPN). Eligible subjects had neuropathic pain refractory to at least two previous analgesic classes; they continued on their prestudy analgesic regimens throughout the trial. Regulatory considerations dictated that subjects smoke under direct observation in a hospital setting. Treatments were placebo and active cannabis ranging in potency between 1 and 8% Delta-9-tetrahydrocannabinol, four times daily for 5 consecutive days during each of 2 treatment weeks, separated by a 2-week washout. The primary outcome was change in pain intensity as measured by the Descriptor Differential Scale (DDS) from a pretreatment baseline to the end of each treatment week. Secondary measures included assessments of mood and daily functioning. Of 127 volunteers screened, 34 eligible subjects enrolled and 28 completed both cannabis and placebo treatments. Among the completers, pain relief was greater with cannabis than placebo (median difference in DDS pain intensity change, 3.3 points, effect size=0.60; p=0.016). The proportions of subjects achieving at least 30% pain relief with cannabis versus placebo were 0.46 (95%CI 0.28, 0.65) and 0.18 (0.03, 0.32). Mood and daily functioning improved to a similar extent during both treatment periods. Although most side effects were mild and self-limited, two subjects experienced treatment-limiting toxicities. Smoked cannabis was generally well tolerated and effective when added to concomitant analgesic therapy in patients with medically refractory pain due to HIV DSPN.

Efficacy of Noradrenergic and Serotonergic Antidepressants in Chronic Back Pain

Although antidepressants are widely prescribed as analgesics in chronic back pain, their clinical pharmacology is not well established. Norepinephrine transporter blockade seems to be essential for analgesia, but optimal concentrations are unknown. Fixed-dose studies of serotonin reuptake inhibitors are generally negative, but such studies cannot be interpreted clearly because efficacy might be detected if concentration-response relationships were known. We evaluated (1) the feasibility of conducting a controlled-concentration study of a norepinephrine (desipramine) and a serotonin reuptake (fluoxetine) inhibitor and (2) the relationship between achieved concentrations and analgesic response. This single-center, 12-week, double-blind, prospective, controlled-concentration study randomized 121 chronic back pain patients without major depression to active placebo (benztropine mesylate) or to predetermined low, medium, or high concentrations of desipramine (targets were 50, 110, and 150 ng/mL, respectively) or fluoxetine (targets were 100, 200, and 400 ng/mL, respectively). Of these, 83 completed the trial: 38 withdrew primarily due to side effects. Manipulation check revealed significant overlap of assigned and achieved concentrations related to drug intolerability. Completers' analysis of achieved concentrations revealed reduction in pain intensity was significantly greater for low-concentration desipramine (<60 ng/mL, mean Descriptor Differential Scale [DDS], 4.5) compared with placebo (DDS 6.2), higher concentrations of desipramine (>60 ng/mL, DDS 7.9), and all concentrations of fluoxetine (P < 0.05, DDS 7.1). Significant improvement in everyday function mirrored findings for pain intensity. Preliminary evidence for a low-concentration "therapeutic window" for noradrenergic analgesia may warrant additional study.

Effects of Hyperbaric Oxygen on Recovery From Exercise-Induced Muscle Damage in Humans

To determine whether hyperbaric oxygen (HBO) therapy could accelerate recovery from exercise-induced muscle damage in humans. Pretest-posttest design with random assignment to either a treatment (HBO) or placebo control (sham) group. University of Alberta and Misericordia Hospital, Edmonton. 12 healthy male students (24.2 +/- 3.2 years) who were unaccustomed to strenuous eccentric exercise of the calf muscles. All subjects performed a strenuous eccentric exercise protocol designed to elicit muscle damage within the right gastrocnemius muscle. Subjects subsequently received either HBO (100% oxygen at 253 kPa [2.5 ATA] for 60 min; n = 6) or sham (atmospheric air at 132 kPa [1.3 ATA] for 60 min; n = 6) treatment conditions. The first treatment was administered 3-4 hours after damage, with a second and third at 24 and 48 hours after the first, respectively. Dependent variables included peak torque at 0.52 radians/s, peak isometric torque, and muscular endurance using isokinetic dynamometry; muscle cross-sectional area using magnetic resonance imaging; inorganic phosphate levels and T2 relaxation time using 31P and 1H magnetic resonance spectroscopy; pain sensation and unpleasantness using the Descriptor Differential Scale. These variables were assessed at baseline and until day 5 postdamage. There was little evidence of a difference in recovery rate between the HBO and sham groups. Faster recovery was observed in the HBO group only for isometric peak torque and pain sensation and unpleasantness. HBO cannot be recommended as an effective method of treatment of this form of muscle injury.

Different effects of strenuous eccentric exercise on the accumulation of neutrophils in muscle in women and men.

The purpose of this study was to evaluate the sex differences in delayed onset muscle soreness (DOMS), torque, and accumulation of technetium-99m (Tc-99m) neutrophils in eccentric-exercised muscle. A group of 10 female and 12 male subjects took part in this study. The subjects completed a pre-test using the descriptor differential scale (DDS) to describe DOMS, and tests of concentric and eccentric torque of the right quadriceps. A volume of 100 ml of blood was taken by venipuncture for neutrophil labelling in the early morning of the exercise day. The Tc-99m neutrophils were re-infused intravenously before the eccentric exercise. The exercise stimulus consisted of 300 eccentric repetitions of the right quadriceps muscles. Radionuclide images of both quadriceps muscles (lateral views) were taken at 2 and 4 h. The DDS, and concentric and eccentric torques of the quadriceps were subsequently evaluated at 0 h, 2, 4, 20 and 24 h post-exercise. The presence of Tc-99m neutrophils was greater in the exercised leg than the non-exercised leg at 2 and 4 h post-exercise (P </= 0.013) and greater in the exercised leg of the women compared to the men at 2 h (P = 0.03). The DOMS had increased post-exercise (P < 0.001) and torque had decreased post-exercise (P </= 0.002) but the patterns were different between the sexes. We concluded that the sex influences the presence of Tc-99m neutrophils in the exercised muscle following eccentric exercise. In addition, different patterns of DOMS and torque were observed between the sexes after eccentric exercise, and require further investigation.

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.

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

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.

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 one's 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

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.

The descriptor differential scale of pain intensity: an evaluation of item and scale properties

Improved methods for pain measurement have both theoretical and clinical importance. This study evaluated the Descriptor Differential Scale (DDS) of Pain Intensity, a recent methodology designed for assessing pain reports in clinical samples. Experiment 1 evaluated the sensitivity of the measure to small changes in electrocutaneous stimulation relative to a traditional visual analogue scale (VAS) of pain intensity. Additionally, direct psychophysical scaling methods were employed to determine ratio-scale values for the DDS sensory items in relation to the electrocutaneous stimuli. This ratio scale was cross-validated by comparison with previously published ratio-scaled data from cross-modality matching pain intensity judgement studies. Experiment 2 evaluated the performance of the measure in both experimental and clinical pain samples, as well as the similarity of item-response patterns in each of these samples. Results indicate that the DDS of Pain Intensity is sensitive to small changes in electrocutaneous stimulation, has consistent ratio-scale properties across two different psychophysical methods, and demonstrates similar item-response patterns across divergent experimental and clinical samples. The results support the validity of the sensory DDS as a measure of pain intensity.

The Descriptor Differential Scale: applying psychophysical principles to clinical pain assessment

The Descriptor Differential Scale (DDS) applies psychophysical principles to clinical pain assessment. It contains 12 descriptor items for each pain dimension assessed. For each item, subjects indicate if their pain either is equal in magnitude to that implied by the anchoring descriptor, or how much greater or lesser on a 10-point graphic scale. The method permits collection of multiple responses, reducing scaling error, and assesses both pain magnitude and scaling consistency. Ninety-one patients completed the sensory intensity and unpleasantness forms of the DDS at both 1 and 2 h after surgical extraction of a lower third molar. Results show that the DDS satisfies standard psychometric criteria for reliability, objectivity and item homogeneity. The coefficients found satisfy standard psychometric criteria and improve after elimination of inconsistent profiles.