The journal of pain : official journal of the American Pain Society
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Previous studies have demonstrated that sex differences in pain responsivity can be detected using various models of experimentally induced pain. The present study employed the mechanical pressure test in order to examine potential differences in pain report among men, normally menstruating women (NMW), and women taking monophasic oral contraceptives (OCW). Testing occurred during 5 phases of the menstrual cycle (menstrual, follicular, ovulatory, luteal, and late luteal) and all participants completed 10 sessions (2 sessions per phase). Menstrual-cycle phase was estimated for OCW based on their first day of menses. Men were tested at time points that roughly corresponded to the intervals during which the different phases occurred in NMW. During the mechanical pressure test, 4 different weights were placed on the fingers, one at a time, and ratings of pain were recorded for 30 seconds. The statistical decision-making model and a forced-choice procedure were used to analyze the response data. Two variables, based on signal detection theory, were thus generated: P(A), a measure of sensory pain, and B, a measure of response bias. P(A) is believed to be a measure of pain sensitivity while B measures stoicism. NMW tended to report lower P(A) values, indicating reduced ability to discriminate among different stimulus intensities, during the menstrual and late luteal phases compared to the luteal phase. OCW reported lower B values, indicating less stoicism, during the menstrual compared to the follicular and ovulatory phases. Men tended to have significantly lower B values than OCW, but not NMW. These results demonstrate subtle menstrual-cycle effects in NMW and OCW. Sex differences were few, with more group differences and trends emerging between OCW and men, as opposed to men and NMW. ⋯ The lack of consistent differences between men and NMW underscores the subtle impact of sex and hormonal changes in pain report. In addition, the data obtained in NMW support the notion that changes in hormone levels during the menstrual cycle can lead to changes in pain responsivity as NMW had trends for better discrimination in menstrual phases when estradiol levels were highest.
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Retraction Of Publication
The effect of intraoperative valdecoxib administration on PGE2 levels in the CSF.
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Randomized Controlled Trial Multicenter Study
Feasibility study of Transcutaneous Electrical Nerve Stimulation (TENS) for cancer bone pain.
This multicenter study assessed the feasibility of conducting a phase III trial of transcutaneous electrical nerve stimulation (TENS) in patients with cancer bone pain recruited from palliative care services. Eligible patients received active and placebo TENS for 1 hour at site of pain in a randomized crossover design; median interval between applications 3 days. Responses assessed at 30 and 60 minutes included numerical and verbal ratings of pain at rest and on movement, and pain relief. Recruitment, tolerability, adverse events, and effectiveness of blinding were also evaluated. Twenty-four patients were randomised and 19 completed both applications. The intervention was well tolerated. Five patients withdrew: 3 due to deteriorating performance status, and 2 due to increased pain (1 each following active and placebo TENS). Confidence interval estimation around the differences in outcomes between active and placebo TENS suggests that TENS has the potential to decrease pain on movement more than pain on rest. Nine patients did not consider that a placebo was used; the remaining 10 correctly identified placebo TENS. Feasibility studies are important in palliative care prior to undertaking clinical trials. Our findings suggest that further work is required on recruitment strategies and refining the control arm before evaluating TENS in cancer bone pain. ⋯ Cancer bone pain is common and severe, and partly mediated by hyperexcitability. Animal studies suggest that Transcutaneous Electrical Nerve Stimulation can reduce hyperalgesia. This study examined the feasibility of evaluating TENS in patients with cancer bone pain in order to optimize methods before a phase III trial.
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Randomized Controlled Trial Multicenter Study
ALO-01 (morphine sulfate and naltrexone hydrochloride) extended-release capsules in the treatment of chronic pain of osteoarthritis of the hip or knee: pharmacokinetics, efficacy, and safety.
ALO-01 (EMBEDA [morphine sulfate and naltrexone hydrochloride] extended-release capsules [King Pharmaceuticals, Inc, Bridgewater, NJ]), indicated for chronic moderate-to-severe pain, is designed to release naltrexone upon tampering (eg, by crushing), reducing morphine-induced subjective effects. This multicenter, randomized, double-blind, crossover study assessed pharmacokinetics, efficacy, and safety of ALO-01 and compared them with extended-release morphine sulfate (ERMS, KADIAN [morphine sulfate extended-release] capsules [Actavis US, Morristown, NJ]) in adults (N = 113) with osteoarthritis pain. Study periods included washout until pain flare (intensity > or =5, 0 to 10; 0 = no pain, 10 = worst pain); dose titration with ERMS (20 to 160mg BID); and randomization to 2 (crossover) 14-day treatment periods with ERMS or ALO-01, separated by 7 days of open-label ERMS. Assessments included pharmacokinetics (morphine, naltrexone), pain scores (0 to 10), Western Ontario and McMaster Universities (WOMAC) Osteoarthritis Index; Patient Global Assessment of Medication (1 to 5; poor to excellent). Mean score at pain flare was 7.1. Morphine exposure from both formulations at steady state was similar. Plasma naltrexone concentrations were below limit-of-quantification for most patients and, when present, did not impact pain scores. During treatment, mean pain intensity (day 14: ERMS, 2.4; ALO-01, 2.3, P = .31), WOMAC change-from-baseline (mean pain, physical function, composite scores), and adverse event frequency were similar. ALO-01 and ERMS provided similar relief of osteoarthritis pain. ⋯ We present data demonstrating that ALO-01 has steady-state morphine exposure, efficacy, and safety similar to marketed ERMS capsules. Results highlight the potential for morphine in ALO-01 to manage moderate-to-severe osteoarthritis pain, while the sequestered naltrexone does not interfere with efficacy.
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Comparative Study
Impact of postherpetic neuralgia and painful diabetic peripheral neuropathy on health care costs.
Knowledge of the health care costs associated with neuropathic pain is limited. Existing studies have not directly compared the health care costs of different neuropathic pain conditions, and patients with neuropathic pain have not been compared with control subjects with the same underlying conditions (for example, diabetes). To determine health care costs associated with postherpetic neuralgia (PHN) and painful diabetic peripheral neuropathy (DPN), patients with these conditions were selected from 2 different administrative databases of health care claims and respectively matched to control subjects who had a diagnosis of herpes zoster without persisting pain or a diagnosis of diabetes without neurological complications using propensity scores for demographic and clinical factors. Total excess health care costs attributable to PHN and painful DPN and excess costs for inpatient care, outpatient/professional services, and pharmacy expenses were calculated. The results indicated that the annual excess health care costs associated with peripheral neuropathic pain in patients of all ages range from approximately $1600 to $7000, depending on the specific pain condition. Total excess health care costs associated with painful DPN were substantially greater than those associated with PHN, which might reflect the great medical comorbidity associated with DPN. ⋯ The data demonstrate that the health care costs associated with 1 peripheral neuropathic pain condition cannot be extrapolated to other neuropathic pain conditions. The results also increase understanding of the economic burden of PHN and painful DPN and provide a basis for evaluating the impact on health care costs of new interventions for their treatment and prevention.