In summary, patients who received NSAIDs:

Benefits in NNT

  • 7.3% reduction in pain intensity within 3 weeks
  • 8.3% reduction in disability within 3 weeks
  • 8% increase in number of patients experiencing global improvement
  • 1 in 14 reduction in pain intensity
  • 1 in 12 reduction in disability
  • 1 in 13 global improvement

Harms in NNT

    No one was harmed
    No one was harmed

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Source: Van der gaag WH, Roelofs PD, Enthoven WT, Van tulder MW, Koes BW. Non-steroidal anti-inflammatory drugs for acute low back pain. Cochrane Database Syst Rev. 2020;4:CD013581.

Study Population: 2,232 patients with acute low back pain from 9 trials comparing NSAIDs with placebo

Efficacy Endpoints: Pain intensity, disability, and proportion of patients experiencing global improvement

Harm Endpoints: Adverse drug effects

Narrative: Low back pain is a common reason for emergency department presentation and is a leading cause of acute disability.1 Up to 70% of individuals experience low back pain during their lifetime.2 Many patients recover from acute back pain within 6 weeks, but some patients experience multiple episodes or chronic pain.3, 4, 5, 6 Guidelines recommend avoidance of bedrest, early activity, patient education, attention to patient psychosocial factors, and administration of analgesic medications.7, 8 Clinical practice guidelines from the American College of Physicians recommend non-steroidal anti-inflammatory drugs (NSAIDs) as a treatment option due to their analgesic and anti-inflammatory properties.8

The Cochrane Review, “Non-steroidal anti-inflammatory drugs for acute low back pain”, summarized here included randomized controlled trials (RCTs) evaluating patients aged 18 years and older who were treated with NSAIDs for acute non-specific low back pain, which was defined as pain above the inferior gluteal folds but below the costal margin that was present for less than 12 weeks.9 The meta-analysis authors excluded studies evaluating chronic low back pain, those with sciatica or acute exacerbations of sciatica, and studies with patients who had underlying pathological conditions such as neoplasm, fracture, or infection. The meta-analysis included study-level data, and primary outcomes included pain intensity, disability, global improvement, adverse events, return to work status, and number of days off of work. Pain intensity and disability were evaluated as continuous outcomes. Pain intensity was measured using the visual analogue scale or numeric rating scale, and disability was evaluated using the Roland-Morris Disability Questionnaire scale in studies investigating NSAIDs versus placebo. A between group difference of more than 10% on the utilized scale was determined to be clinically relevant.

The authors identified 32 RCTs (n = 5356 patients) that met inclusion criteria, of which 9 RCTs (n = 2232 patients) evaluated NSAIDs versus placebo.9 For this Brass Tacks, we focused on studies evaluating NSAIDs versus placebo, which demonstrate the highest quality data and greatest applicability to emergency medicine. The NSAIDs evaluated included ibuprofen, Accepted Article piroxicam, dipyrone, tenoxicam, and diclofenac. Treatment periods ranged from 1 day to 4 weeks, and follow-up periods from 1 day to 2 months. Study settings included general practitioner clinics, outpatient clinics, and the emergency department.

NSAID use was associated with a mean reduction in pain intensity of -7.29 (95% confidence interval [CI]: -10.98 to -3.61) on a 100-point visual analogue scale, with a number needed to treat (NNT) of 14. NSAIDs reduced disability compared to placebo (MD: -2.02, 95% CI: -2.89 to -1.15) on the 24-point Roland-Morris Disability Questionnaire scale, with a NNT of 12. NSAIDs demonstrated an 8% absolute increase and NNT of 13 for global improvement compared to placebo. Time to return to work and the proportion of patients who had adverse events were not significantly different between NSAIDs and placebo.

Caveats: There are important limitations of these findings, most importantly the variable quality of evidence and risk of bias. All nine included trials compared NSAIDs with placebo, finding a reduction in pain intensity and short-term disability and an increase in global improvement with the former. Four studies reported on pain intensity, with moderate quality of evidence; the mean difference in pain intensity was 7.29, less than the clinically significant difference of 12 on a 100 point scale.10 Only two trials reported on short-term disability within 3 weeks; the differences were small and of unclear clinical relevance. Five trials reported on global improvement, but there was significant heterogeneity in the scales used and the types of outcomes measured. Studies also used different cutoff points for outcomes such as global improvement and modes of medication delivery. Most of the trials evaluating adverse events had small sample sizes and were not sufficiently powered to exclude a clinically significant difference.

Further limitations include variation in the duration of follow-up among studies, with only 3 trials having follow-up greater than 3 weeks. At least five trials were industry-sponsored, with other studies not fully describing sponsorship, which can increase the risk of bias. The most commonly identified biases were performance bias and attrition bias. Incomplete information about randomization and allocation concealment introduced a risk of selection bias, and most studies were not registered, increasing the risk of selective reporting. The diversity of study populations resulted in heterogeneity, and subjects were drawn from a variety of general practitioner and outpatient clinics, which may not fully reflect the same patients evaluated for this in the emergency department. Finally, not all outcome measures were reported in the 9 RCTs evaluating NSAIDs with placebo; for example, outcomes related to return to work and long-term follow-up were unavailable for many trials.

Based on this evidence, we have assigned a color recommendation of Yellow (Unclear if benefits) for use of NSAIDs in patients with acute LBP, as the magnitude of effect was small and of questionable clinical relevance. Further data are needed to more fully evaluate the role of NSAIDs for acute low back pain in the emergency department setting.

The original manuscript was published in Academic Emergency Medicine as part of the partnership between TheNNT.com and AEM.

Author: Brit Long, MD; Michael Gottlieb, MD
Supervising Editors: Allan Wolfson, MD; Fredrik Amell, MD

Published/Updated: August 24, 2020

  1. The Title Bar

    The title bar is color-coded with our overall recommendation.

    • Green: Benefits outweigh risks.
    • Yellow: Unclear risk/benefit profile.
    • Red: Benefits do not outweigh risks.
    • Black: Obvious harms, no clear benefits.
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