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Evidence-Based Physiatry

Topical Analgesics for Acute and Chronic Pain in Adults - An Overview of Cochrane Reviews

Paganoni, Sabrina, MD, PhD

American Journal of Physical Medicine & Rehabilitation: July 2018 - Volume 97 - Issue 7 - p 531–532
doi: 10.1097/PHM.0000000000000949
Evidence-Based Physiatry
Free

From the Department of PM&R, Harvard Medical School, Spaulding Rehabilitation Hospital, Boston, Massachusetts.

All correspondence should be addressed to: Sabrina Paganoni, MD, PhD, Massachusetts General Hospital, 165 Cambridge St, Suite 600, Boston, MA 02114.

Financial disclosure statements have been obtained, and no conflicts of interest have been reported by the authors or by any individuals in control of the content of this article.

Clinical practice is being shaped by secular trends emphasizing outcome metrics, cost-effectiveness, and value. Physiatrists are not immune from these trends. Within this context, it is critical to have direct access to rehabilitation-relevant evidence to provide the most effective physiatric care. However, clinicians may find it burdensome to extract rehabilitation-relevant evidence from an exponentially growing body of complex medical literature. This monthly column is meant to provide physiatrists with rapid, to-the-point, and actionable Evidence-Based Physiatry (EBP). We define EBP as a systematic approach to clinical problem-solving that takes into consideration the best available medical evidence. Equipped with this evolving and emerging knowledge, physiatrists will be well positioned to deliver high-quality care by integrating EBP with their own clinical expertise and patient values.

A notable contribution to EBP was the establishment of Cochrane Rehabilitation as a Field within the Cochrane organization in October 2016. Since then, Cochrane has identified 76 previously completed Cochrane Reviews that were deemed of relevance for the field of rehabilitation. This list serves as a valuable resource for EBP in several health conditions and care setting of rehabilitation interest (full list available at http://rehabilitation.cochrane.org/evidence). In this first issue of EBP, we will summarize one of the Cochrane reviews of rehabilitation interest and will examine its relevance for the practice of physiatry.

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TOPICAL ANALGESICS FOR ACUTE AND CHRONIC PAIN IN ADULTS: AN OVERVIEW OF COCHRANE REVIEWS

Cochrane has produced 13 reviews on the topic of topical analgesics for the treatment of acute and chronic pain in adults. An overview of their findings was published in May 20171 and includes data from 206 studies with 30,700 participants. The analysis was conducted by the Pain, Palliative, and Supportive Care Review group within Cochrane (http://www.cochranelibrary.com/) and its detailed conclusions as well as plain language summary (“Do painkillers rubbed on the skin really work?”) are available online at http://cochranelibrary-wiley.com/doi/10.1002/14651858.CD008609.pub2/full. The goal of this Cochrane review is to “provide an overview of the analgesic efficacy and associated adverse events of topical analgesics […] applied to intact skin for the treatment of acute and chronic pain in adults.”1

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Clinical Questions

Do topical analgesics provide effective pain relief? If so, which preparations work best and for what painful conditions? Are there any safety concerns?

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Why Is This Relevant for Physiatrists?

Topical analgesics are used broadly to relieve pain in a variety of clinical settings. They are an appealing first line choice in certain painful conditions due to empiric efficacy reported by some individuals, good safety profile, and broad availability. With so many available compounds, though, it may be challenging for physiatrists to identify the most effective agents and select the most appropriate clinical indications.

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Summary Answer

There is good evidence to support the use of specific preparations of nonsteroidal anti-inflammatory drugs (NSAIDs) in selected painful conditions, both acute (“strains or sprains”) and chronic (hand or knee osteoarthritis). Adverse effects were uncommon.

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Research Findings

The primary outcome was at least 50% pain relief as reported by participants in trials of topical analgesics versus placebo. Outcomes were measured after about 1 wk of treatment for acute musculoskeletal conditions (“strains or sprains”) and after up to 12 wks of treatment for osteoarthritis of the hand or knee. The number needed to treat for one additional beneficial outcome (number needed to treat [NNT]) was extracted for each preparation.

For acute musculoskeletal pain (strains and sprains), several NSAIDs helped reduce pain by at least 50% (mean NNT was 1.8 for diclofenac Emulgel, 2.5 for ketoprofen gel, 4.7 for diclofenac Flector plaster, 3.2 for diclofenac other plaster, 4.4 for piroxicam gel).

In hand and knee osteoarthritis, topical diclofenac and ketoprofen helped reduce pain by at least 50% in a modest number of people (mean NNT for diclofenac preparations was 5 for <9 wks of treatment and 9.8 for 6 to 12 wks of treatment; mean NNT for ketoprofen was 6.9 for 6 to 12 wks of treatment).

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What Is the Impact of These Findings on Physiatric Clinical Practice?

There is good evidence to support the use of specific formulations of topical NSAIDs in acute pain conditions, such as strains or sprains, and in chronic pain due to hand and knee osteoarthritis. There is good evidence that the exact formulation used is important in acute musculoskeletal conditions as the NNT varied by specific formulation. Topical NSAIDs have a favorable side effect profile.

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What Questions Remain Outstanding?

High-quality studies are available only for selected topical preparations and clinical conditions as summarized previously. More research is needed to determine whether other topical agents (including other NSAIDs, lidocaine, and herbal remedies) are effective. Furthermore, the applicability of these findings to other painful conditions (e.g., chronic pain not related to osteoarthritis) deserves further investigation.

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REFERENCE

1. Derry S, Wiffen PJ, Kalso EA, et al: Topical analgesics for acute and chronic pain in adults - an overview of Cochrane Reviews. Cochrane Database Syst Rev 2017;5:CD008609
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