Pain
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Meta Analysis
Seeking a simple measure of analgesia for mega-trials: is a single global assessment good enough?
We sought to investigate the potential of using a simple global estimation ('How effective do you think the treatment was?') as a measure of efficacy by comparing it with at least 50%maxTOTPAR (at least 50% of the maximum possible pain relief) in acute pain studies. One hundred and fifty randomized, double-blind trials included in 11 systematic reviews of single dose, oral analgesics for postoperative pain were used as a source of data. The relationship between the proportion of patients reporting the top two or three values on a five-point global scale and the proportion with at least 50%maxTOTPAR was investigated. ⋯ Individual patient data were also used from four randomized, placebo-controlled, double-blind trials in postoperative pain. The frequency distribution for %maxTOTPAR was plotted for patients reporting each of the five categories on the global scale. A global assessment provides similar measures of analgesic efficacy as TOTPAR derived from hourly measurements, but the effects of adverse effects have yet to be understood.
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Randomized Controlled Trial Clinical Trial
A cognitive-behavioral return-to-work program: effects on pain patients with a history of long-term versus short-term sick leave.
A cognitive-behavioral return-to-work focused program was evaluated in a randomized controlled design, and the effects were compared between two groups of women with musculoskeletal pain. One group of patients (n=36) had a history of long-term sick leave (>12 months) at the start of the program and the other (n=36) had a history of short-term sick leave (2-6 months). The outpatient treatment program, conducted by a psychologist, included 12 sessions with the primary aim to help the patients return-to-work. ⋯ The results showed that the cognitive-behavioral return-to-work program was more effective than the treatment-as-usual control condition in reducing the number of days on sick leave for patients on short-term sick leave, but not for patients on long-term sick leave. The treatment program also helped the patients on short-term sick leave to increase their ability to control and decrease pain and to increase their general activity level compared to the control condition. These results underscore the need for an early return-to-work focused rehabilitation to prevent long-term sick leave and disability.
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Although individuals with fibromyalgia syndrome (FMS) consistently report wide-spread pain, clear evidence of structural abnormalities or other sources of chronic stimulation of pain afferents in the involved body areas is lacking. Without convincing evidence for peripheral tissue abnormalities in FMS patients, it seems likely that a central pathophysiological process is at least partly responsible for FMS, as is the case for many chronic pain conditions. Therefore, the present study sought to obtain psychophysical evidence for the possibility that input to central nociceptive pathways is abnormally processed in individuals with long standing FMS. ⋯ Within series of stimuli, FMS subjects reported increases in sensory magnitude to painful levels for interstimulus intervals of 2-5 s, but pain was evoked infrequently at intervals greater than 2 s for control subjects. Following the last stimulus in a series, after-sensations were greater in magnitude, lasted longer and were more frequently painful in FMS subjects. These results have multiple implications for the general characterization of pain in FMS and for an understanding of the underlying pathophysiological basis.
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Positron emission tomography (PET) imaging of spinal cord in monkeys with a cholinergic tracer demonstrates increased spinal cholinergic activity in response to an analgesic dose of morphine, and this PET result correlates with measurement of acetylcholine spillover into spinal cord extracellular space induced by morphine, as measured by microdialysis. Previous studies in rats, mice, and sheep demonstrate activation of spinal cholinergic neurons by systemic opioid administration, and participation of this cholinergic activity in opioid-induced analgesia. Testing the relevance of this observation in humans has been limited to measurement of acetylcholine spillover into lumbar cerebrospinal fluid. ⋯ The one animal which did not show increased spinal cholinergic activity by PET from this dose of morphine also did not show increased acetylcholine from this morphine dose in the microdialysis experiment. These data confirm the ability to use PET to image spinal cholinergic terminals in the monkey spinal cord and suggest that acute changes in cholinergic activity can be imaged with this non-invasive technique. Following preclinical screening, PET scanning with [(18)F]FBT may be useful to investigate mechanisms of analgesic action in normal humans and in those with pain.
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Recent research indicates that people who are fearful of pain tend to report more negative pain experiences. It also seems that attentional mechanisms may be particularly important in the perception of painful stimuli, especially amongst pain fearful individuals. Drawing on a paradigm used to examine biased cognitive processes in the emotional disorders, the current study investigated whether the fear of pain would be related to a greater selective attentional bias in favour of pain-related stimuli. ⋯ No group differences were found for either social threat or positive stimuli. These results indicate that one reason why those with a high fear of pain are particularly susceptible to negative pain experiences could be due to biased attentional processes. Suggestions for cognitive interventions designed to reduce such biases are discussed, as are directions for future research.