Lorna Mason

Systematic review of topical capsaicin for the treatment of chronic pain

Abstract Objective To determine the efficacy and safety of topically applied capsaicin for chronic pain from neuropathic or musculoskeletal disorders. Data sources Cochrane Library, Medline, Embase, PubMed, an in-house database, and contact with manufacturers of topical capsaicin. Study selection Randomised controlled trials comparing topically applied capsaicin with placebo or another treatment in adults with chronic pain. Data extraction Primary outcome was dichotomous information for the number of patients with about a 50% reduction in pain. Outcomes were extracted at four weeks for musculoskeletal conditions and eight weeks for neuropathic conditions. Secondary outcomes were adverse events and withdrawals due to adverse events. Data synthesis Six double blind placebo controlled trials (656 patients) were pooled for analysis of neuropathic conditions. The relative benefit from topical capsaicin 0.075% compared with placebo was 1.4 (95% confidence interval 1.2 to 1.7) and the number needed to treat was 5.7 (4.0 to 10.0). Three double blind placebo controlled trials (368 patients) were pooled for analysis of musculoskeletal conditions. The relative benefit from topical capsaicin 0.025% or plaster compared with placebo was 1.5 (1.1 to 2.0) and the number needed to treat was 8.1 (4.6 to 34). Around one third of patients experienced local adverse events with capsaicin, which would not have been the case with placebo. Conclusions Although topically applied capsaicin has moderate to poor efficacy in the treatment of chronic musculoskeletal or neuropathic pain, it may be useful as an adjunct or sole therapy for a small number of patients who are unresponsive to, or intolerant of, other treatments.

Topical NSAIDs for acute pain: a meta-analysis

BackgroundA previous systematic review reported that topical NSAIDs were effective in relieving pain in acute conditions like sprains and strains, with differences between individual drugs for efficacy. More trials, a better understanding of trial quality and bias, and a reclassification of certain drugs necessitate a new review.MethodsStudies were identified by searching electronic databases and writing to manufacturers. We selected randomised double blind trials comparing topical NSAID with either placebo or another active treatment in adults with acute pain, and extracted dichotomous information approximating to a 50% reduction in pain at one week, together with details of adverse events and withdrawals. Relative benefit and number-needed-to-treat (NNT), and relative risk and number-needed-to-harm (NNH) were calculated, with sensitivity analyses where appropriate to investigate differences between individual drugs and aspects of trial design.ResultsTwenty-six double blind placebo controlled trials had information from 2,853 patients for evaluation of efficacy. Topical NSAID was significantly better than placebo in 19 of the 26 trials, with a pooled relative benefit of 1.6 (95% confidence interval 1.4 to 1.7), and NNT of 3.8 (95% confidence interval 3.4 to 4.4) compared with placebo for the outcome of half pain relief at seven days. Results were not affected by outcome reported, or condition treated, but smaller trials yielded a larger estimate of efficacy. Indirect comparisons of individual topical NSAIDs showed that ketoprofen was significantly better than all other topical NSAIDs, while indomethacin was barely distinguished from placebo. Three trials, with 433 patients, compared topical with oral NSAID (two trials compared the same drug, one compared different drugs) and found no difference in efficacy. Local adverse events, systemic adverse events, or withdrawals due to an adverse event were rare, and no different between topical NSAID and placebo.ConclusionsTopical NSAIDs were effective and safe in treating acute painful conditions for one week.

Systematic review of efficacy of topical rubefacients containing salicylates for the treatment of acute and chronic pain

Abstract Objective To determine the efficacy and safety of topical rubefacients containing salicylates in acute and chronic pain. Data sources Electronic databases and manufacturers of salicylates. Study selection Randomised double blind trials comparing topical rubefacients with placebo or another active treatment, in adults with acute or chronic pain, and reporting dichotomous information, around a 50% reduction in pain, and analyses at one week for acute conditions and two weeks for chronic conditions. Data extraction Relative benefit and number needed to treat, analysis of adverse events, and withdrawals. Data synthesis Three double blind placebo controlled trials had information on 182 patients with acute conditions. Topical salicylate was significantly better than placebo (relative benefit 3.6, 95% confidence interval 2.4 to 5.6; number needed to treat 2.1, 1.7 to 2.8). Six double blind placebo controlled trials had information on 429 patients with chronic conditions. Topical salicylate was significantly better than placebo (relative benefit 1.5, 1.3 to 1.9; number needed to treat 5.3, 3.6 to 10.2), but larger, more valid studies were without significant effect. Local adverse events and withdrawals were generally rare in trials that reported them. Conclusions Based on limited information, topically applied rubefacients containing salicylates may be efficacious in the treatment of acute pain. Trials of musculoskeletal and arthritic pain suggested moderate to poor efficacy. Adverse events were rare in studies of acute pain and poorly reported in those of chronic pain. Efficacy estimates for rubefacients are unreliable owing to a lack of good clinical trials.

Outcomes in acute pain trials: systematic review of what was reported?

&NA; Single‐dose clinical trial methods for evaluating analgesics have been used successfully for over 50 years. The aims of this review were to examine which pain measurement scales have been used in high quality acute pain trials, to investigate other common measurements or characteristics, to confirm that different scales used by standard methods give the same estimate of analgesic effect, to investigate remedication methodologies and the potential of ‘time to remedication’ as a standard outcome. Published reports of randomised, double blind, placebo‐controlled trials, investigating at least 20 adult patients (10 patients per treatment arm) experiencing moderate or severe pain using at least one standard pain intensity or pain relief scale were sought. Key design features, outputs and outcomes were catalogued for each report. The main outcomes reported were misleading, detailing only the mean values of data with a demonstrably skewed distribution. After 50 years, the reporting of results from acute pain trials warrants a fresh look. Possible improvements include reporting the number of patients with certain levels of pain relief, or the actual number (percentage) of patients with a certain level of pain relief at a certain time, or more useful information on remedication from trials of at least 12 h duration. Most useful would be all three. Further exploration would only be possible from analysis at the individual patient level.

Single-dose oral naproxen for acute postoperative pain: a quantitative systematic review

BackgroundNaproxen and naproxen sodium are non-steroidal anti-inflammatory drugs used in a variety of painful conditions, including the treatment of postoperative pain. This review aims to assess the efficacy, safety and duration of action of a single oral dose of naproxen/naproxen sodium for moderate to severe acute postoperative pain in adults, compared with placebo.MethodsThe Cochrane Library (issue 4 2002), EMBASE, PubMed, MEDLINE and an in-house database were searched for randomised, double blind, placebo controlled trials of a single dose of orally administered naproxen or naproxen sodium in adults with acute postoperative pain. Pain relief or pain intensity data were extracted and converted into dichotomous information to give the number of patients with at least 50% pain relief over 4 to 6 hours. Relative benefit and number-needed-to-treat were then calculated. The percentage of patients with any adverse event, number-needed-to-harm, and time to remedication were also calculated.ResultsTen trials with 996 patients in met the inclusion criteria. Six trials compared naproxen sodium 550 mg (252 patients) with placebo (248 patients); the NNT for at least 50% pain relief over six hours was 2.6 (95% confidence interval 2.2 to 3.2). There was no significant difference between the number of patients experiencing any adverse event on treatment compared with placebo. Weighted mean time to remedication was 7.6 hours for naproxen sodium 550 mg (206 patients) and 2.6 hours for placebo (205 patients). Four other trials used lower doses.ConclusionA single oral dose of naproxen sodium 550 mg is an effective analgesic in the treatment of acute postoperative pain. A low incidence of adverse events was found, although these were not reported consistently.