Trend in methodological quality of randomised clinical trials in low back pain

During the past decades, the number of published randomised clinical trials evaluating the efficacy of conservative treatments for low back pain has substantially increased. At the same time several initiatives were undertaken in order to improve the methodological quality of published randomised clinical trials, also in the field of low back pain. We investigated how the methodological quality of randomised clinical trials in the field of low back pain developed over time since the first published trial in 1961. Methodological scores of 269 RCTs included in 15 Cochrane reviews of conservative treatment for low back pain were compared. Overall many trials showed methodological shortcomings. The median overall quality scores ranged from 36 to 82% depending on the type of intervention. There were no improvements in median overall methodological quality over time from 1960 to 2004. Improvements were apparent for a few validity criteria only.