The journal of pain : official journal of the American Pain Society
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Randomized Controlled Trial Multicenter Study Comparative Study
Reciprocal relationship between pain and depression: a 12-month longitudinal analysis in primary care.
Pain and depression are the most prevalent physical and psychological symptom-based disorders, respectively, and co-occur 30 to 50% of the time. However, their reciprocal relationship and potentially causative effects on one another have been inadequately studied. Longitudinal data analysis involving 500 primary care patients with persistent back, hip, or knee pain were enrolled in the Stepped Care for Affective Disorders and Musculoskeletal Pain (SCAMP) study. Half of the participants had comorbid depression and were randomized to a stepped care intervention (n = 123) or treatment as usual (n = 127). Another 250 nondepressed patients with similar pain were followed in a parallel cohort. Outcomes were assessed at baseline, 3, 6, and 12 months. Mixed effects model repeated measures (MMRM) multivariable analyses were conducted to determine if change in pain severity predicted subsequent depression severity, and vice versa. Change in pain was a strong predictor of subsequent depression severity (t-value = 6.63, P < .0001). Likewise, change in depression severity was an equally strong predictor of subsequent pain severity (t-value = 7.28, P < .0001). Results from the full cohort were similar in the clinical trial subgroup. In summary, pain and depression have strong and similar effects on one another when assessed longitudinally over 12 months. ⋯ This study strengthens the evidence for a bidirectional and potentially causative influence of pain and depression on one another. A change in severity of either symptom predicts subsequent severity of the other symptom. Thus, recognition and management of both conditions may be warranted, particularly when treatment focused on 1 condition is not leading to an optimal response.
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Randomized Controlled Trial
Reliability and validity of a brief method to assess nociceptive flexion reflex (NFR) threshold.
The nociceptive flexion reflex (NFR) is a physiological tool to study spinal nociception. However, NFR assessment can take several minutes and expose participants to repeated suprathreshold stimulations. The 4 studies reported here assessed the reliability and validity of a brief method to assess NFR threshold that uses a single ascending series of stimulations (Peak 1 NFR), by comparing it to a well-validated method that uses 3 ascending/descending staircases of stimulations (Staircase NFR). Correlations between the NFR definitions were high, were on par with test-retest correlations of Staircase NFR, and were not affected by participant sex or chronic pain status. Results also indicated the test-retest reliabilities for the 2 definitions were similar. Using larger stimulus increments (4 mAs) to assess Peak 1 NFR tended to result in higher NFR threshold estimates than using the Staircase NFR definition, whereas smaller stimulus increments (2 mAs) tended to result in lower NFR threshold estimates than the Staircase NFR definition. Neither NFR definition was correlated with anxiety, pain catastrophizing, or anxiety sensitivity. In sum, a single ascending series of electrical stimulations results in a reliable and valid estimate of NFR threshold. However, caution may be warranted when comparing NFR thresholds across studies that differ in the ascending stimulus increments. ⋯ This brief method to assess NFR threshold is reliable and valid; therefore, it should be useful to clinical pain researchers interested in quickly assessing inter- and intra-individual differences in spinal nociceptive processes.
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Randomized Controlled Trial
Efficacy of low-dose celecoxib in patients with acute pain.
The sore throat pain model was used to evaluate single-dose effects of celecoxib 50 and 100 mg over 6 hours in the treatment of acute pharyngeal pain. Multiple-dose effects of 50-mg bid and 100 mg followed by 50 mg over 6 to 24 hours were also evaluated. Under double-blind, randomized, placebo-controlled conditions, 269 adults with confirmed acute pharyngitis rated throat pain intensity, throat soreness, difficulty swallowing, and sore throat pain relief over 24 hours. For the primary efficacy analysis (SPID2), patients receiving celecoxib 100 mg during the first 2 hours after the first dose had significantly higher mean scores than patients in the placebo group (P < .0003). Efficacy was also demonstrated for celecoxib 50 and 100 mg compared with placebo for all end points (including total pain relief, summed pain intensity differences, total reduction of throat soreness, and difficulty swallowing) at all time points after the first dose and after the second 50-mg dose (P < .01). There were no differences between the dosage regimens, although a supplementary 50-mg dose of celecoxib 6 to 12 hours after the first dose appeared to provide additional efficacy over 24 hours. No serious adverse events (AEs) or discontinuations due to an AE were reported. The results of this study demonstrate that in this pain model, celecoxib is a well tolerated and efficacious analgesic in 50- and 100-mg doses. ⋯ In a double-blind, randomized, placebo-controlled trial utilizing the sore throat pain model, low-dose celecoxib (50- and 100-mg doses) was well tolerated and provided effective analgesia in patients with acute pain.
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Randomized Controlled Trial Multicenter Study
Subcutaneous methylnaltrexone for treatment of opioid-induced constipation in patients with chronic, nonmalignant pain: a randomized controlled study.
Methylnaltrexone is effective for opioid-induced constipation (OIC) in advanced illness patients. This 4-week, double-blind, randomized, placebo-controlled study investigated the effect of subcutaneous methylnaltrexone on OIC in patients receiving opioids for chronic, nonmalignant pain. Patients (N = 460) received subcutaneous methylnaltrexone 12 mg once daily (QD) or every other day (alternating with placebo) compared with placebo. Assessments included bowel movement count, time of bowel movement, straining, sense of complete evacuation, Bristol Stool Form Scales, and quality of life. Within 4 hours of first dose, 34.2% of patients in both methylnaltrexone groups had rescue-free bowel movements (RFBMs) versus 9.9% on placebo (P < .001). The estimated number needed to treat was about 4. On average, 28.9% of methylnaltrexone QD and 30.2% of methylnaltrexone alternate-day dosing resulted in RFBMs within 4 hours versus 9.4% QD and 9.3% alternate-day placebo injections (both P < .001). Both methylnaltrexone groups had significantly shorter time to first RFBM (P < .001) and greater increase in number of weekly RFBMs (P < .05) versus placebo. Adverse events included abdominal pain, diarrhea, nausea, and hyperhidrosis. Bristol Stool Form Scale scores (P = .002) and sensation of complete evacuation (P < .04) were significantly superior with methylnaltrexone QD; both methylnaltrexone groups reported no or mild straining during RFBMs in the first 2 weeks (P < .02). At 4 weeks, a significantly greater improvement in patient-reported, constipation-specific quality of life was seen in the alternate-day dosing (P < .05) and QD (P < .001) groups. ⋯ We present data demonstrating that subcutaneous methylnaltrexone 12 mg given once daily (QD) or every other day provides significant relief of OIC and was generally well tolerated in patients with chronic, nonmalignant pain. These results expand on prior effectiveness observed for the treatment of OIC in advanced illness patients to a broader population.
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Randomized Controlled Trial
Transcranial DC stimulation in fibromyalgia: optimized cortical target supported by high-resolution computational models.
In this study we aimed to determine current distribution and short-term analgesic effects of transcranial direct current stimulation (tDCS) in fibromyalgia using different electrode montages. For each electrode montage, clinical effects were correlated with predictions of induced cortical current flow using magnetic resonance imaging-derived finite element method head model. Thirty patients were randomized into 5 groups (Cathodal-M1 [primary motor cortex], Cathodal-SO [supra-orbital area], Anodal-M1, Anodal-SO, and Sham) to receive tDCS application (2 mA, 20 minutes) using an extracephalic montage. Pain was measured using a visual numerical scale (VNS), pressure pain threshold (PPT), and a body diagram (BD) evaluating pain area. There was significant pain reduction in cathodal-SO and anodal-SO groups indexed by VNS. For PPT there was a trend for a similar effect in anodal-SO group. Computer simulation indicated that the M1-extracephalic montage produced dominantly temporo-parietal current flow, consistent with lack of clinical effects with this montage. Conversely, the SO-extracephalic montage produced current flow across anterior prefrontal structures, thus supporting the observed analgesic effects. Our clinical and modeling findings suggest that electrode montage, considering both electrodes, is critical for the clinical effects of M1-tDCS as electric current needs to be induced in areas associated with the pain matrix. These results should be taken into consideration for the design of pain tDCS studies. ⋯ Results in this article support that electrode montage is a critical factor to consider for the clinical application of tDCS for pain control, as there is an important correlation between the location of induced electrical current and tDCS-induced analgesic effects.