Strengths and limitations
low back pain, pain
BLIND
As regards the strength of this study, the results are justified by some important methodological features known to minimise bias in clinical trials. These features include RCT design, power analysis, concealed allocation, blind outcome assessment and intention-to-treat analysis. Additionally, per-protocol and responder analyses were conducted.The present study also had some limitations which should be considered when interpreting the results. First, our study had a substantial attrition rate, particularly during the 20-week follow-up (> 20%). However, the results of the intention-to-treat analysis were nearly comparable to those of the per-protocol analysis. Second, outcomes were only evaluated in the shorter-term, and longer-term effect is unknown. Third, we did not include a control group which would have allowed estimation of truly significant effects and minimise the assumption that improvement may be attributable to the natural course of low back pain. Fourth, we could not preclude potential contamination of the study interventions with other pain treatments even though the participants were informed to refrain from such treatments. Fifth, self-report questionnaires were used as outcome measures, which may be subject to recall bias from the participants. Lastly, it was difficult to compare the results of the current study with previous studies as the content of the interventions, especially the PE programme varied markedly.