Pain
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Randomized Controlled Trial Multicenter Study
A multicenter, randomized, triple-masked, placebo-controlled trial of the effect of ambulatory continuous femoral nerve blocks on discharge-readiness following total knee arthroplasty in patients on general orthopaedic wards.
A continuous femoral nerve block (cFNB) involves the percutaneous insertion of a catheter adjacent to the femoral nerve, followed by a local anesthetic infusion, improving analgesia following total knee arthroplasty (TKA). Portable infusion pumps allow infusion continuation following hospital discharge, raising the possibility of decreasing hospitalization duration. We therefore used a multicenter, randomized, triple-masked, placebo-controlled study design to test the primary hypothesis that a 4-day ambulatory cFNB decreases the time until each of three predefined readiness-for-discharge criteria (adequate analgesia, independence from intravenous opioids, and ambulation 30m) are met following TKA compared with an overnight inpatient-only cFNB. ⋯ Patients who were given 4 days of perineural ropivacaine attained all three criteria in a median (25th-75th percentiles) of 47 (29-69)h, compared with 62 (45-79)h for those of the control group (Estimated ratio=0.80, 95% confidence interval: 0.66-1.00; p=0.028). Compared with controls, patients randomized to ropivacaine met the discharge criterion for analgesia in 20 (0-38) versus 38 (15-64)h (p=0.009), and intravenous opioid independence in 21 (0-37) versus 33 (11-50)h (p=0.061). We conclude that a 4-day ambulatory cFNB decreases the time to reach three important discharge criteria by an estimated 20% following TKA compared with an overnight cFNB, primarily by improving analgesia.
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Randomized Controlled Trial Comparative Study
A comparison of the effect of attention training and relaxation on responses to pain.
This study aimed to investigate the efficacy of an attention training technique (ATT) on pain ratings, threshold and tolerance during the cold pressor task. One hundred and three undergraduate students were randomly assigned to receive either threat-alleviating or threat-inducing information about the task. Participants were then re-randomized to receive either ATT or progressive muscle relaxation (PMR). ⋯ These results show that ATT changes the cognitive processes of internal/external focus and hypervigilance towards sensory pain words, but not difficulty disengaging or mindfulness. Although ATT changed threshold, the fact that neither pain ratings nor tolerance was affected suggests that a single, brief session of ATT may not be sufficient to affect broader change. Nonetheless, this study shows that ATT can change cognitive processes thought to be associated with heightened perception of pain and that this changes how quickly pain is registered and is therefore worthy of further investigation.
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Randomized Controlled Trial
Increased basal mechanical pain sensitivity but decreased perceptual wind-up in a human model of relative hypocortisolism.
Clinical data have accumulated showing that relative hypocortisolism, which may be regarded as a neuroendocrinological correlate of chronic stress, may be a characteristic of some functional pain syndromes. However, it has not been clarified yet whether deregulations of the hypothalamus-pituitary-adrenal (HPA) axis may directly alter pain perception and thus be causally involved in the pathophysiology of these disorders. To test this hypothesis, we performed a randomized placebo-controlled crossover trial in N=20 healthy drug-free volunteers (median age 24yrs) and analyzed the effects of metyrapone-induced hypocortisolism on quantitatively assessed basal mechanical pain sensitivity (1.5-13m/s impact stimuli), perceptual wind-up (9m/s impact stimuli at 1Hz) and temporal summation of pain elicited by inter-digital web pinching (IWP; 10N pressure stimuli for 2min). ⋯ Perceptual wind-up by contrast was reduced when cortisol synthesis was blocked (p<.05). This result is reminiscent of findings from animal studies showing a reversal of NMDA receptor activation by glucocorticoid receptor antagonists in neuropathic pain models. Our results speak in favor of a potential causal role of HPA axis alterations in pain chronicity.
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Randomized Controlled Trial
Fibromyalgia: Moderate and substantial pain intensity reduction predicts improvement in other outcomes and substantial quality of life gain.
Chronic pain is associated with a range of other problems, including disturbed sleep, depression, anxiety, fatigue, reduced quality of life, and an inability to work or socialise. We investigated whether good symptom control of pain (using definitions of moderate and substantial benefit) is associated with improvement in other symptoms. Individual patient data from four randomised trials in fibromyalgia (2575 patients) lasting 8-14weeks were used to calculate percentage pain reduction for each completing patient (1858), divided into one of five groups according to pain reduction, irrespective of treatment: substantial benefit - 50% pain reduction; moderate - 30% to <50%; minimal - 15% to <30%; marginal - 0% to <15%; worse - <0% (increased pain intensity). ⋯ Substantial pain intensity reduction resulted in 0.11 QALYs gained, and moderate pain intensity reduction in 0.07 QALYs gained over a 12-month period. Substantial and moderate pain intensity reduction predicts broad beneficial outcomes and improved quality of life that do not occur without pain relief. Pain intensity reduction is a simple and effective predictor of which patients should continue treatment, and which should discontinue and try an alternative therapy.
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Randomized Controlled Trial Multicenter Study
How do changes in pain severity levels correspond to changes in health status and function in patients with painful diabetic peripheral neuropathy?
The current analysis compares changes in pain with changes in function and health status in individuals with painful diabetic peripheral neuropathy (DPN). The post hoc analysis is based on a 12week, multinational, placebo-controlled trial of pregabalin in which 401 patients were randomized to treatment. Study measures included the Brief Pain Inventory short-form (BPI-sf), EQ-5D and other patient-reported outcomes. ⋯ Similarly, a reduction in the NRS of 30% and 50% corresponded to a 3-point and a 5-point improvement in the PII, respectively. Changes in pain were also associated with changes in health status. Results suggest that patients whose pain is not reduced to a mild level of severity can still experience clinically important changes in function and health status.