Pain
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Randomized Controlled Trial
Identifying specific profiles in patients with different degrees of painful knee osteoarthritis based on serological biochemical and mechanistic pain biomarkers: a diagnostic approach based on cluster analysis.
Biochemical and pain biomarkers can be applied to patients with painful osteoarthritis profiles and may provide more details compared with conventional clinical tools. The aim of this study was to identify an optimal combination of biochemical and pain biomarkers for classification of patients with different degrees of knee pain and joint damage. Such profiling may provide new diagnostic and therapeutic options. ⋯ Four distinct knee pain profiles were identified: profile A (N = 27), profile B (N = 59), profile C (N = 85), and profile D (N = 41). Each knee pain profile had a unique combination of biochemical markers, pain biomarkers, physical impairments, and psychological factors that may provide the basis for mechanism-based diagnosis, individualized treatment, and selection of patients for clinical trials evaluating analgesic compounds. These results introduce a new profiling for knee OA and should be regarded as preliminary.
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Pain-related depression of behavior and mood is a key therapeutic target in the treatment of pain. Clinical evidence suggests a role for decreased dopamine (DA) signaling in pain-related depression of behavior and mood. Similarly, in rats, intraperitoneal injection of dilute lactic acid (IP acid) serves as a chemical noxious stimulus to produce analgesic-reversible decreases in both (1) extracellular DA levels in nucleus accumbens (NAc) and (2) intracranial self-stimulation (ICSS), an operant behavior reliant on NAc DA. ⋯ In the absence of the noxious stimulus, amitifadine increased NAc levels of both DA and serotonin, and behaviorally, amitifadine produced significant but weak abuse-related ICSS facilitation. Moreover, amitifadine was more potent to block IP acid-induced depression of ICSS than to facilitate control ICSS. These results support consideration of amitifadine and related monoamine uptake inhibitors as candidate analgesics for treatment of pain-related behavioral depression.
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Attentional bias to pain among family caregivers of patients with pain may enhance the detection of pain behaviors in patients. However, both relatively high and low levels of attentional bias may increase disagreement between patients and caregivers in reporting pain behaviors. This study aims to provide further evidence for the presence of attentional bias to pain among family caregivers, to examine the association between caregivers' attentional bias to pain and detecting pain behaviors, and test whether caregivers' attentional bias to pain is curvilinearly related to patient and caregiver disagreement in reporting pain behaviors. ⋯ Importantly, caregivers' attentional bias to pain was significantly positively associated with reporting pain behaviors in patients above and beyond pain severity. It is reassuring that attentional bias to pain was not related to disagreement between patients and caregivers in reporting pain behaviors. In other words, attentional bias does not seem to cause overestimation of pain signals.
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Patients with knee osteoarthritis demonstrate decreased pressure pain thresholds (PPTs), facilitated temporal summation (TS) of pain, and decreased conditioned pain modulation (CPM) compared with healthy controls. This study aimed to correlate preoperative PPTs, TS, and CPM with the development of chronic postoperative pain after total knee replacement (TKR) surgery. Knee pain intensity (visual analog scale [VAS]: 0-10), PPTs, TS, and CPM were collected before, 2 months, and 12 months after TKR. ⋯ Preoperative TS level correlated to 12-month postoperative VAS (R = 0.240, P = 0.037). Patients who developed moderate-to-severe pain had pronociceptive changes compared with patients who developed mild pain postsurgery. Preoperative TS level correlated with the postoperative pain intensity and may be a preoperative mechanistic predictor for the development of chronic postoperative pain in patients with osteoarthritis after TKR.