This review assessed traction for patients with low back pain. The authors concluded that the evidence remains inconclusive, largely due to the poor quality of the studies included in the review. The authors' conclusions are likely to be reliable, although it is noted that it was not the evidence that was inconclusive, but their interpretation of the evidence.

To examine the efficacy of traction for participants with low back pain (LBP) with or without radiating pain.

MEDLINE, CINAHL, AMED, the Cochrane Library and PEDro were searched from 1966 to December 2001 for publications in the English language; the search terms were provided. The authors also handsearched journals and reference lists for additional relevant references.

Study designs of evaluations included in the review

Randomised controlled trials (RCTs) were included in the review.

Specific interventions included in the review

To be eligible for inclusion, one of the intervention groups had to receive traction (e.g. motorised traction, autotraction, manual traction, or gravitational traction given continuously or intermittently), while the placebo group had to receive sham traction (low-weight or ineffective traction) or another conservative treatment modality (e.g. hot packs, massage). Studies that compared different types of traction were excluded from the review.

Participants included in the review

Participants over the age of 18 years who were treated for LBP with or without radiating pain were eligible for inclusion. Radiating pain was defined as pain localised below the scapula and above the cleft of the buttocks, with or without radiation to the lower extremities. Participants with LBP resulting from disease conditions such as infection, neoplasm, osteoporosis, rheumatoid arthritis, or fractures were excluded from the review.

Outcomes assessed in the review

To be eligible for inclusion, the studies had to evaluate one or more of the following outcomes: pain, global measure of improvement, back pain-specific functional status, or generic functional status or quality of life.

How were decisions on the relevance of primary studies made?

The authors did not state how the papers were selected for the review. One reviewer performed the selection.

The authors assessed validity using criteria recommended by the Cochrane Back Review Group. The authors did not explicitly state how the validity assessment was performed.

The authors did not state how the data were extracted for the review. One reviewer performed the data extraction.

A study was considered positive if traction was reported to be more effective than the control group treatment, or negative if there was no difference between the treatment groups, or if the control group was more effective than the group receiving traction. A study was considered inconclusive if there were conflicting results between the primary outcome measures.

How were the studies combined?

A narrative synthesis of the studies was undertaken since the authors considered a meta-analysis inappropriate, owing to heterogeneity. The authors examined the results by the type of comparator examined (traction versus placebo or sham traction, and traction versus another conservative treatment modality), and by the type of traction used (i.e. motorised traction). In addition, the authors examined the studies with regard to the appropriateness of the treatment intervention. For this section of the review, the authors examined a subset of studies that met additional inclusion criteria.

How were differences between studies investigated?

Where possible, the authors also subcategorised the studies by chronicity: acute (less than 6 weeks), subacute (6 to 12 weeks) or chronic (greater than 12 weeks).

Thirteen RCTs were included in the review. These provided data from at least 1,171 participants (some studies did not provide the sample size).

Only one of the 13 RCTs was considered to be of a high quality; the overall quality of the studies was low.

Six studies compared lumbar traction with placebo or sham traction. Only one of these studies was a high-quality study, and all but one reported no significant differences between the treatment and control groups; one study was inconclusive.

Seven studies compared lumbar traction with other conservative treatments. Two of the studies reported a significant improvement in the traction group compared with the other treatments.

Seven trials evaluated the effectiveness of motorised traction. Two of these compared motorised traction with sham traction and both reported no significant differences between the groups. The other five trials compared motorised traction with conservative treatment. Three of these reported no significant differences between the interventions, while two reported significant findings in favour of traction.

Four studies examined recommended clinical parameters. Two reported no beneficial effects compared with controls, while two reported positive findings.

The authors concluded that, owing to the lack of methodological rigour, the evidence for the use of traction in LBP remains inconclusive. There was also limited evidence about the effectiveness of the most clinically appropriate interventions.

The review question and inclusion and exclusion criteria were clearly presented. The authors searched a number of databases, but only English language publications were retrieved, thus introducing language bias into the review. The authors acknowledged this limitation and stated that research on traction has traditionally taken place in the Netherlands and in Germany. The authors assessed the quality of the studies very thoroughly. The results of this assessment were presented in data extraction tables and were incorporated in the narrative synthesis. The authors did not, however, explicitly state how many reviewers performed the validity assessment. It was reported that one reviewer selected and data extracted the included studies. Having more than one reviewer in the review process ensures that steps are taken to minimise bias.

The authors stated that the evidence for the use of traction remains inconclusive. This conclusion is likely to be reliable if the evidence-base is of poor quality (which it appears to be). However, it might have been clearer to summarise the available evidence, with the caveat that the results were not likely to be reliable.

Practice: The authors did not state any implications for practice.

Research: The authors stated that further high-quality trials of clinically appropriate interventions are needed.

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.