Background: Many therapies exist for the treatment of low-back pain including spinal manipulative therapy (SMT), which is a worldwide, extensively practised intervention. This report is an update of the earlier Cochrane review, first published in January 2004 with the last search for studies up to January 2000.
Objectives: To examine the effects of SMT for acute low-back pain, which is defined as pain of less than six weeks duration.
Search methods: A comprehensive search was conducted on 31 March 2011 in the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, CINAHL, PEDro, and the Index to Chiropractic Literature. Other search strategies were employed for completeness. No limitations were placed on language or publication status.
Selection criteria: Randomized controlled trials (RCTs) which examined the effectiveness of spinal manipulation or mobilization in adults with acute low-back pain were included. In addition, studies were included if the pain was predominantly in the lower back but the study allowed mixed populations, including participants with radiation of pain into the buttocks and legs. Studies which exclusively evaluated sciatica were excluded. No other restrictions were placed on the setting nor the type of pain. The primary outcomes were back pain, back-pain specific functional status, and perceived recovery. Secondary outcomes were return-to-work and quality of life. SMT was defined as any hands-on therapy directed towards the spine, which includes both manipulation and mobilization, and includes studies from chiropractors, manual therapists, and osteopaths.
Data collection and analysis: Two review authors independently conducted the study selection and risk of bias (RoB) assessment. Data extraction was checked by the second review author. The effects were examined in the following comparisons: SMT versus 1) inert interventions, 2) sham SMT, 3) other interventions, and 4) SMT as an additional therapy. In addition, we examined the effects of different SMT techniques compared to one another. GRADE was used to assess the quality of the evidence. Authors were contacted, where possible, for missing or unclear data. Outcomes were evaluated at the following time intervals: short-term (one week and one month), intermediate (three to six months), and long-term (12 months or longer). Clinical relevance was defined as: 1) small, mean difference (MD) < 10% of the scale or standardized mean difference (SMD) < 0.4; 2) medium, MD = 10% to 20% of the scale or SMD = 0.41 to 0.7; and 3) large, MD > 20% of the scale or SMD > 0.7.
Main results: We identified 20 RCTs (total number of participants = 2674), 12 (60%) of which were not included in the previous review. Sample sizes ranged from 36 to 323 (median (IQR) = 108 (61 to 189)). In total, six trials (30% of all included studies) had a low RoB. At most, three RCTs could be identified per comparison, outcome, and time interval; therefore, the amount of data should not be considered robust. In general, for the primary outcomes, there is low to very low quality evidence suggesting no difference in effect for SMT when compared to inert interventions, sham SMT, or when added to another intervention. There was varying quality of evidence (from very low to moderate) suggesting no difference in effect for SMT when compared with other interventions, with the exception of low quality evidence from one trial demonstrating a significant and moderately clinically relevant short-term effect of SMT on pain relief when compared to inert interventions, as well as low quality evidence demonstrating a significant short-term and moderately clinically relevant effect of SMT on functional status when added to another intervention. In general, side-lying and supine thrust SMT techniques demonstrate a short-term significant difference when compared to non-thrust SMT techniques for the outcomes of pain, functional status, and recovery.
Authors' conclusions: SMT is no more effective in participants with acute low-back pain than inert interventions, sham SMT, or when added to another intervention. SMT also appears to be no better than other recommended therapies. Our evaluation is limited by the small number of studies per comparison, outcome, and time interval. Therefore, future research is likely to have an important impact on these estimates. The decision to refer patients for SMT should be based upon costs, preferences of the patients and providers, and relative safety of SMT compared to other treatment options. Future RCTs should examine specific subgroups and include an economic evaluation.