Elsevier

The Lancet

Volume 384, Issue 9954, 1–7 November 2014, Pages 1586-1596
The Lancet

Articles
Efficacy of paracetamol for acute low-back pain: a double-blind, randomised controlled trial

https://doi.org/10.1016/S0140-6736(14)60805-9Get rights and content

Summary

Background

Regular paracetamol is the recommended first-line analgesic for acute low-back pain; however, no high-quality evidence supports this recommendation. We aimed to assess the efficacy of paracetamol taken regularly or as-needed to improve time to recovery from pain, compared with placebo, in patients with low-back pain.

Methods

We did a multicentre, double-dummy, randomised, placebo controlled trial across 235 primary care centres in Sydney, Australia, from Nov 11, 2009, to March 5, 2013. We randomly allocated patients with acute low-back pain in a 1:1:1 ratio to receive up to 4 weeks of regular doses of paracetamol (three times per day; equivalent to 3990 mg paracetamol per day), as-needed doses of paracetamol (taken when needed for pain relief; maximum 4000 mg paracetamol per day), or placebo. Randomisation was done according to a centralised randomisation schedule prepared by a researcher who was not involved in patient recruitment or data collection. Patients and staff at all sites were masked to treatment allocation. All participants received best-evidence advice and were followed up for 3 months. The primary outcome was time until recovery from low-back pain, with recovery defined as a pain score of 0 or 1 (on a 0–10 pain scale) sustained for 7 consecutive days. All data were analysed by intention to treat. This study is registered with the Australian and New Zealand Clinical Trial Registry, number ACTN 12609000966291.

Findings

550 participants were assigned to the regular group (550 analysed), 549 were assigned to the as-needed group (546 analysed), and 553 were assigned to the placebo group (547 analysed). Median time to recovery was 17 days (95% CI 14–19) in the regular group, 17 days (15–20) in the as-needed group, and 16 days (14–20) in the placebo group (regular vs placebo hazard ratio 0·99, 95% CI 0·87–1·14; as-needed vs placebo 1·05, 0·92–1·19; regular vs as-needed 1·05, 0·92–1·20). We recorded no difference between treatment groups for time to recovery (adjusted p=0·79). Adherence to regular tablets (median tablets consumed per participant per day of maximum 6; 4·0 [IQR 1·6–5·7] in the regular group, 3·9 [1·5–5·6] in the as-needed group, and 4·0 [1·5–5·7] in the placebo group), and number of participants reporting adverse events (99 [18·5%] in the regular group, 99 [18·7%] in the as-needed group, and 98 [18·5%] in the placebo group) were similar between groups.

Interpretation

Our findings suggest that regular or as-needed dosing with paracetamol does not affect recovery time compared with placebo in low-back pain, and question the universal endorsement of paracetamol in this patient group.

Funding

National Health and Medical Research Council of Australia and GlaxoSmithKline Australia.

Introduction

Low-back pain is the leading cause of disability worldwide.1 Guidelines for acute low-back pain universally recommend paracetamol as the first-line analgesic.2, 3 Although the effect of paracetamol for low-back pain is similar to that of other analgesics used for low-back pain,4, 5 no direct evidence supports this universal recommendation. In a systematic review6 we noted no evidence to support the use of paracetamol for low-back pain. All seven of the included trials had substantial methodological flaws, and only one trial included more than 25 participants per group. No trial has compared paracetamol with placebo or compared as-needed dosing with the regular recommended dosing. In view of these uncertainties, the Paracetamol for Low-Back Pain Study (PACE) aimed to investigate the efficacy of paracetamol taken regularly or as-needed to improve time to recovery from pain, compared with placebo for patients with acute low-back pain. PACE also aimed to establish whether regular or as-needed paracetamol improved short-term pain (1–12 weeks), disability, function, global rating of symptom change, sleep, or quality of life compared with placebo.

Section snippets

Trial design and participants

PACE was a multicentre, double-dummy, randomised, placebo controlled trial. The study protocol7 and analysis plan8 have been published. In brief, 235 primary care clinicians (181 general practitioners, 50 pharmacists, and four physiotherapists) across Sydney, Australia, screened consecutive patients who sought care for low-back pain directly or in response to a community advertisement. Inclusion criteria were a new episode of acute low-back pain (defined as pain between the 12th rib and buttock

Results

From Nov 11, 2009, to Dec 13, 2012, 4606 patients were screened and 1652 patients were randomly assigned to treatment groups (figure 1). The mean age was 45 years (SD 16) and 876 (53%) patients were men. Nine patients were excluded by a masked researcher after randomisation because new information provided to researchers meant that these patients did not initially meet the eligibility criteria (figure 1). Of the 1643 participants, 550 were allocated to the regular group, 546 to the as-needed

Discussion

We have shown that neither regular nor as-needed dosing of paracetamol improved recovery compared with placebo. Consistent with the primary results, paracetamol also had no effect on pain, disability, function, global symptom change, sleep, or quality of life. Adverse events between treatment groups did not differ.

PACE was a large, high-quality, multicentre trial. The trial setting matches the recommendations in guidelines that low-back pain should mainly be managed in primary care.2, 3

References (28)

  • RA Davies et al.

    A systematic review of paracetamol for non-specific low back pain

    Eur Spine J

    (2008)
  • CM Williams et al.

    PACE—the first placebo controlled trial of paracetamol for acute low back pain: design of a randomised controlled trial

    BMC Musculoskelet Disord

    (2010)
  • CM Williams et al.

    PACE—the first placebo controlled trial of paracetamol for acute low back pain: statistical analysis plan

    Trials

    (2013)
  • CKS Ong et al.

    An evidence-based update on nonsteroidal anti-inflammatory drugs

    Clin Med Res

    (2007)
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