Research Review By Dr. Joshua Plener©


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Date Posted:

March 2022

Study Title:

Effectiveness of treatments for acute and subacute mechanical non-specific low back pain: a systematic review with network meta-analysis


Gianola S, Bargeri S, Castillo G et al.

Author's Affiliations:

Unit of Clinical Epidemiology, IRCCS Istituto Ortopedico Galeazzi, Milano; Department of Biomedical Science for Health, University of Milan, Italy

Publication Information:

British Journal of Sports Medicine 2022; 56: 41-50. doi:10.1136/bjsports-2020-103596

Background Information:

Low back pain is a leading cause of disability, significantly impacting the lives of many (1). Approximately one in four American adults report low back pain within (LBP) the previous 3 months that lasted at least 24 hours and 7.6% of adults report at least one episode of severe acute low back pain within a 1-year period (2). Generally, LBP has a good prognosis with most non-specific acute and sub-acute episodes significantly improving within 6 weeks. However, approximately 2 out of 3 individuals continue to experience pain at 3 months and 12 months (3).

Most guidelines recommend that for acute LBP, a first line care approach should be offered, consisting of advice, reassurance, and encouragement to engage in light, tolerable physical activity (4). For second line treatment, a range of options exist including pharmacological and physical therapy. However, the relative effects of interventions when compared against other interventions are not well known. Therefore, this systematic review aims to understand the efficacy of currently available treatments for acute and subacute mechanical non-specific low back pain.

Pertinent Results:

Literature Search Results:
6779 records were retrieved with 46 studies included in the final analysis. In total, 8765 participants were included with sample sizes ranging from 21.5 to 91.3 participants. Of the 46 studies, 9 had a low risk of bias, 20 unclear and 17 had a high risk of bias.

At the immediate-term follow-up, 35 studies assessed pain. Within the network meta-analysis, there were 15 direct comparisons to inert treatment between 10 different treatment nodes, which demonstrated standardized mean differences for exercise at -1.4, heat wrap at -1.38, opioids at -0.86, manual therapy at -0.72, and non-steroidal anti-inflammatory drugs at -0.53. The most effective treatment identified was exercise (for immediate-term follow-up – within 1 week).

At the short-term follow-up, manual therapy significantly reduced pain compared with inert treatment, with a standardized mean difference of -0.83.

At medium-term follow-up, manual therapy was superior to inert treatment in reducing pain at 3-6 months.

At long-term follow-up, the most effective treatment was cognitive behavioural therapy, but this finding was not statistically significant.

Disability was assessed in 21 studies at the immediate-term follow-up, 14 studies at 1-month follow-up, 11 studies at 3-6 months follow-up, and 7 studies at 12-months follow-up.

At the immediate term follow-up, the standardized mean difference for exercise is -0.71, heat wrap is -0.59, manual therapy is -0.52, and education is -0.28. These treatments were statistically significant compared with inert treatment, with the most effective treatment being manual therapy.

In the short-term follow-up, manual therapy was statistically significant compared with education and exercise and a positive trend was found in favour of low dose steroids compared to NSAIDs.

In the medium-term follow-up (3-6 months), low dose steroids were statistically significant compared to NSAIDs, as well as manual therapy compared to education and exercise.

In the long-term follow-up, no intervention was statistically significant against inert treatment, with the most effective treatment being cognitive behavioural therapy.

Adverse Events:
26 studies reported adverse events. No events were reported for acupuncture, education, exercise or manual therapy, and mild-moderate events occurred in interventions consisting of heat wrap, muscle relaxants, NSAIDS, opioids, paracetamol, steroids and inert treatment. Mild-moderate adverse events occurred most often in the opioids, NSAIDs and steroid treatment arms.

Clinical Application & Conclusions:

This study found that for acute and subacute mechanical non-specific low back pain, pharmacological and non-pharmacological interventions were more effective than inert treatment for reducing pain intensity and disability. Overall, the certainty of evidence ranged from very low to moderate, with high certainty of evidence for manual therapy (including chiropractic!) compared with usual care and education (education is an important adjunct but is not as effective in isolation).

For pain, the most effective interventions at immediate-term follow-up were heat wrap, manual therapy, exercise, NSAIDs, and opioids, whereas at short-term, manual therapy was the most effective treatment. For trials assessing disability, similar findings were revealed.

This analysis highlights (once again) that non-pharmacological interventions (including chiropractic) should be the first-line treatment, and medication has a relatively minor role for nonspecific acute and subacute low back pain.

Study Methods:

The following electronic data bases were searched from inception to February 27th, 2019 and updated on October 17th, 2020: Medline, CENTRAL, Embase. Studies published in languages other than English were classified as potentially eligible, but not entered in the final review.

Eligibility Criteria:
  • Randomized controls trials (RCTs) involving both adult men and women experiencing pain for up to 12 weeks due to acute or subacute nonspecific-low back pain were included (5).
  • Trials assessing nonpharmacological treatments including acupuncture and dry needling or pharmacological treatments for improving pain and/or reducing disability were included.
  • The comparator group was an inert treatment consisting of sham/placebo or no treatment(s).
Outcomes Assessed:
The primary outcomes assessed were pain intensity and disability, with secondary outcomes being occurrence of adverse events. Follow-up time was classified as immediate (closest to 1 week), short-term (closest to 1-month assessment), medium-term (closest to 3-6 months) and long-term (closest to 12 months).

Study Selection and Risk of Bias Assessment:
Two independent reviewers screened titles and abstracts and extracted study characteristics and outcome data. Risk of bias was assessed using the Cochrane RoB tool, which assesses random sequence generation, allocation concealment, blinding of participants, providers and outcome assessment, incomplete outcome data (dropouts) and selective outcome reporting. Furthermore, the certainty of evidence was assessed through the GRADE approach.

Meta-Analysis and Network Meta-Analysis:
Conventional pair wise meta-analysis was performed using a random effects model for each treatment comparison with at least 2 included studies. In addition, a network meta-analysis (NMA) was completed to assess direct and indirect evidence (note: NMA is a technique for comparing three or more interventions simultaneously in a single analysis by combining both direct and indirect evidence across a network of studies). To ensure that studies are similar in order to allow the estimation of effects of indirect comparisons in a network meta-analysis, effect modifiers must be similar across the included trials. Effect modifiers are trial characteristics that result in heterogeneity in meta-analyses, such as frequency of treatment. In non-specific low back pain research, there have been no robust effect modifiers established, therefore, potential modifiers were determined based on clinical and methodological experience. These modifiers included the stage of low back pain, presence of leg pain or sciatica, mean age, percentage of male participants, baseline severity, length of treatment, number of randomized subjects and psychological assessment. Following this, intervention treatment nodes were determined.

Results were summarized with standardized mean differences when different outcome measurements were reported for each trial.

Study Strengths / Weaknesses:

  • This study is one of, if not the largest network meta-analysis completed to date in the field of low back pain.
  • When assessing the network meta-analysis, the authors evaluated important clinical and demographic modifiers of treatment response at the individual patient level.
  • Head to head comparisons of the same interventions were excluded. This was done as the aim for this project was not to inspect different characteristics of delivery such as intensity, dose, and techniques. This could be an interesting project itself!
  • Around 24% of included trials had a small sample size of less than 30 patients per intervention arm.

Additional References:

  1. Hoy D, March L, Brooks P, et al. The global burden of low back pain: estimates from the global burden of disease 2010 study. Ann Rheum Dis 2014; 73: 968–74.
  2. Patrick N, Emanski E, Knaub MA. Acute and chronic low back pain. Med Clin North Am 2014; 98: 777–89.
  3. da C Menezes Costa L, Maher CG, Hancock MJ, et al. The prognosis of acute and persistent low-back pain: a meta-analysis. CMAJ 2012; 184: E613–24.
  4. Almeida M, Saragiotto B, Richards B, et al. Primary care management of non-specific low back pain: key messages from recent clinical guidelines. Med J Aust 2018; 208: 272–5.
  5. van Tulder M, Becker A, Bekkering T, et al. Chapter 3. European guidelines for the management of acute nonspecific low back pain in primary care. Eur Spine J 2006; 15 Suppl 2: S169–91.

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