Trial sequential analysis of 60 randomised controlled trials found that sufficient evidence on spinal manipulative therapy for chronic low back pain was reached by 2002 for functional status and 2004 for pain, meaning subsequent trials have constituted research waste.
- Analysis of 60 trials (10,312 participants) found futility boundaries were crossed by 2002-2004
- Further RCTs after these dates have not added to understanding of spinal manipulation effectiveness
- Authors recommend avoiding further trials without novel research questions
How this compares to prior research
Chronic low back pain is the leading cause of years lived with disability worldwide. Spinal manipulation therapy is recommended in clinical guidelines and supported by randomised trials, but systematic review conclusions have remained unchanged despite a growing evidence base. This suggests that new trials may not be adding meaningful information to what was already known from earlier research.
Low back pain prevalence among global population, 1990–1999
Key findings
- For functional status outcomes, the futility and information size boundary was crossed in 2002, indicating sufficient evidence had been gathered
- For pain outcomes at 1 month, the futility boundary was reached in 2004 when comparing spinal manipulative therapy to other conservative treatments
- 60 randomised controlled trials involving 10,312 participants were included in the trial sequential analysis
What this means in practice
- Avoid enrolling in new trials testing standard spinal manipulation for chronic low back pain without novel elements
- Ask researchers to justify how new back pain studies differ from existing evidence before participating
- Recognise that treatment guidelines already have sufficient evidence from trials completed over 20 years ago
Frequently asked questions
What is research waste in clinical trials?
Research waste occurs when studies continue to be conducted after sufficient evidence has already been gathered to answer a question, using resources that could address unanswered questions instead.
Does this mean spinal manipulation doesn't work for back pain?
No, it means we\’ve had enough evidence since 2002-2004 to know its effectiveness. The study addresses redundant research, not whether the treatment works.
What is trial sequential analysis?
It\’s a method that determines when enough evidence has accumulated across multiple trials to draw firm conclusions, similar to calculating sample size for a single study.
Key terms explained
Trial Sequential Analysis
A statistical method that determines when enough evidence has accumulated across multiple trials to draw reliable conclusions.
Futility Boundary
A statistical threshold indicating that further research is unlikely to change conclusions about an intervention\’s effectiveness.
Spinal Manipulative Therapy
A treatment involving hands-on techniques to adjust or mobilise the spine, commonly performed by chiropractors and physical therapists.
Source: Research Waste in Randomised Control Trials of Spinal Manipulative Therapy for Chronic Low Back Pain: Evidence From Trial Sequential Analysis. · DOI: doi: 10.1002/ejp.70270