The journal of pain : official journal of the American Pain Society
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Randomized Controlled Trial
Beliefs about pharmaceutical medicines and natural remedies explain individual variation in placebo analgesia.
This study examined whether placebo responses were predicted by a theoretical model of specific and general treatment beliefs. Using a randomized crossover, experimental design (168 healthy individuals) we assessed whether responses to a cold pressor task were influenced by 2 placebo creams described as pharmaceutical versus natural. We assessed whether placebo responses were predicted by pretreatment beliefs about the treatments (placebo) and by beliefs about the pain. ⋯ Treatment necessity beliefs also partially mediated the effects of helplessness on placebo responses. Treatment necessity beliefs for the pharmaceutical placebo were influenced by general pharmaceutical beliefs whereas necessity beliefs for the natural placebo were informed by general background beliefs about holistic treatments. Our findings show that treatment beliefs influence the placebo effect suggesting that they may offer an additional approach for understanding the placebo effect.
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Randomized Controlled Trial
Minocycline prevents muscular pain hypersensitivity and cutaneous allodynia produced by repeated intramuscular injections of hypertonic saline in healthy human participants.
Minocycline, a glial suppressor, prevents behavioral hypersensitivities in animal models of peripheral nerve injury. However, clinical trials of minocycline in human studies have produced mixed results. This study addressed 2 questions: can repeated injections of hypertonic saline (HS) in humans induce persistent hypersensitivity? Can pretreatment with minocycline, a tetracycline antibiotic with microglial inhibitory effects, prevent the onset of hypersensitivity? Twenty-seven healthy participants took part in this double-blind, placebo-controlled study, consisting of 6 test sessions across 2 weeks. ⋯ Placebo-treated participants experienced a bilateral 35% alleviation in muscle soreness (P < .0001), with no changes to the prevalence of cold allodynia. In contrast, minocycline-treated participants experienced a bilateral 70% alleviation in muscle soreness (P < .0001), additionally, only 10% of minocycline-treated participants showed cold allodynia. This study showed that repeated injections of HS can induce a hypersensitivity that outlasts the acute response, and the development of this hypersensitivity can be reliably attenuated with minocycline pretreatment.
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The aim of the present study was to examine the incidence and predictors of persistent prescription opioid use 4 months after traumatic injury. Adults who sustained a traumatic musculoskeletal injury were recruited to participate in this observational prospective, longitudinal study within 14 days of injury (T1) and followed for 4 months (T2). Measures included questionnaires on pain, opioid consumption, pain disability, anxiety, depression, and posttraumatic stress symptoms as well as a chart review for injury related information. ⋯ At T2, 35.3% (n = 43) patients were using prescription opioids. After controlling for age, sex, injury severity, T1 pain severity, and T2 symptoms of depression, 2 factors emerged as significantly related to T2 prescription opioid use; namely, T2 pain severity (odds ratio = 1.248, 95% confidence interval, 1.071-1.742) and T2 pain self-efficacy (odds ratio = .943, 95% confidence interval, .903-.984). These results suggest that opioid use after traumatic musculoskeletal injury is related to pain severity and how well patients cope specifically with their pain, over and above other psychological factors, such as depression and anxiety.
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Acute postsurgical pain (APSP) is a common and anticipated problem after surgery with detrimental consequences if not appropriately managed. This study examined the independent and joint contribution of presurgical demographic, clinical, and psychological variables as predictors of APSP intensity, evaluated using an 11-point numeric rating scale, after inguinal hernioplasty, one of the most performed surgeries worldwide. In a prospective observational cohort study, a consecutive sample of 135 men undergoing hernioplasty was assessed before and 48 hours after surgery. ⋯ The integrative predictive model found in this study revealed the simultaneous influence that demographic, clinical, and psychological factors have on APSP after inguinal hernioplasty. Therefore, these results improve knowledge on APSP predictors after inguinal hernioplasty and highlight potential modifiable intervention targets, such as anxiety and pain catastrophizing (rumination), for the design of interventions focused on APSP prevention and management. Hence, taken together, these findings lend support for the inclusion of presurgical screening and psychological interventions among surgical patients at risk for higher APSP intensity.
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Facilitated pain mechanisms and impaired pain inhibition are often found in chronic pain patients. This study compared clinical pain profiles, pain sensitivity, as well as pronociceptive and antinociceptive mechanisms in patients with localized low back pain (n = 18), localized neck pain (n = 17), low back and radiating leg pain (n = 18), or neck and radiating arm pain (n = 17). It was hypothesized that patients with radiating pain had facilitated pain mechanisms and impaired pain inhibition compared with localized pain patients. ⋯ Temporal summation of pain was increased in patients with radiating back pain compared with localized back pain (P < .03). Patients with radiating arm pain or localized low back pain demonstrated hyperalgesia to heat and pressure in nonpainful body areas (P < .05), as well as well as a facilitated clinical pain profile compared with patients with localized neck pain (P = .03). Patients with radiating pain patterns demonstrated facilitated temporal summation suggesting differences in the underlying pain mechanisms between patients with localized back pain and radiating pain.