Trends over time in the size and quality of randomised controlled trials of interventions for chronic low-back pain

Article type
Authors
Henschke N1, Kuijpers T2, Rubinstein S3, van Middelkoop M4, Ostelo R3, Verhagen A4, Koes B4, van Tulder M5
1Musculoskeletal Division, The George Institute for Global Health, Australia
2Dutch Institute for Healthcare Improvement CBO, Netherlands
3EMGO Institute for Health and Care Research, Netherlands
4Department of General Practice, ErasmusMC, Netherlands
5Department of Health Sciences, VU University, Netherlands
Abstract
Background: Despite the high prevalence and enormous burden of chronic low-back pain (CLBP), there remains uncertainty regarding the most effective form of therapy. This continuing uncertainty is often considered to be due to methodological shortcomings or a lack of adequate reporting. In light of the increasing number of randomised controlled trials (RCTs) and continuing initiatives to improve the quality of clinical research, it could be expected that the methodological quality of RCTs in the field of CLBP may have improved during recent years.

Objectives: This study aimed to identify and describe trends over time in the study design characteristics and risk of bias in CLBP trials performed over the past 30 years.

Methods: We extracted 157 randomised trials of interventions for CLBP from four recently published systematic reviews. The reviews included RCTs on physical and rehabilitation interventions, injection therapy and denervation procedures, complementary and alternative therapies, and pharmacological interventions for chronic LBP. Study level data were extracted and analysed for trends associated with year of publication.

Results: Overall, the mean sample size in the RCTs was 141 (median70; range17 to 3093). There was a slight increase in the median number of risk of bias criteria fulfilled from trials published prior to 1995 to those published after 1996. The analysis showed that in more recent years RCTs of medical interventions were more likely to be successfully blinded than RCTs of non-medical interventions.

Conclusions: Over the past 30 years, the number of RCTs for CLBP has increased exponentially. However, there does not appear to be a corresponding increase in sample size or a decrease in risk of bias. Further research is needed into specific risks of bias within RCTs for CLBP and the effect they have on the plausibility of the results.