KEY QUESTION 1. What are the benefits and harms of spinal manipulation/chiropractic services for acute lower back pain (less than 6 weeks duration) compared to usual care or other forms of acute pain management?

Twenty-six studies of SMT treatments for acute low back pain found overall statistically significant evidence of a clinical benefit that was, on average, modest. However, there was substantial heterogeneity in results, with some studies reporting much larger effects and some studies reporting no effect at all. We explored 6 potential sources of heterogeneity, and while there were some non-statistically significant differences that may be signals of possible effects of type of manipulation, selection of patients, and study quality, most of the differences in outcome between studies remain unexplained.

Mild transient musculoskeletal adverse events are common following SMT, although these may be equally common following non-SMT manual therapy. Serious adverse events have been the subject of case reports, but assessing causality has proved challenging.

There were too few studies of SMT in patients with acute back pain and sciatica to draw conclusions.

Mild transient musculoskeletal adverse events are common following SMT, although these may be equally common following non-SMT manual therapy. Serious adverse events have been the subject of case reports, but assessing causality has proved challenging.

There were too few studies of SMT in patients with acute back pain and sciatica to draw conclusions.

KEY QUESTION 1A. What is the relationship between the use of spinal manipulation/chiropractic services for lower back pain and the use of opiate medication?

Among the 26 studies included in our analysis only one specifically reported on the use of opiate medications.

KEY QUESTION 2. What are the benefits and harms of spinal manipulation/chiropractic services for acute neck pain (less than 6 weeks duration) compared to usual care or other forms of acute pain management?

Only 5 studies were identified of SMT compared to a non-SMT treatment group for patients with acute neck pain. Although each study reported favorable results on at least one outcome, in total only 198 patients have been studied.

KEY QUESTION 2A. What is the relationship between the use of spinal manipulation/chiropractic services for neck pain and the use of opiate medication?

None of the included studies reported on the use of analgesic medications or opiate medication as an outcome.

Publication Bias

In general we did not find evidence of publication bias, although no evidence of bias is not the same as evidence of no publication bias.

Study Quality

Study quality was highly variable and our pooled analysis is split about equally between studies considered “high” and studies considered “low” quality. Our analysis found no evidence to support a hypothesis that our results are due to low-quality studies with inflated effect sizes.

Heterogeneity

Heterogeneity in the results is the primary limitation of this analysis. The statistical evidence of heterogeneity was significant and visual inspection of the forest plots illustrated this: some studies of SMT found, for the same outcome, found positive results, while others found essentially no benefit (ES = 0, ES = 0.06, etc). Our investigation of multiple potential sources of heterogeneity yielded no results that were statistically significant, although visually there were suggestions that the comparison group, the patients, and the type of SMT may be important. Nevertheless, the majority of heterogeneity remains unexplained and this larger degree of heterogeneity may limit the enthusiasm of some clinicians and policymakers for advocating more widespread use of SMT.

Applicability of Findings to the VA Population

We identified no studies specific to VA population. Nevertheless, acute back pain in primary care is probably quite similar within VA to outside VA, and these results have to be considered at least moderately applicable to VA populations.