Methodological shortcomings make conclusion highly sensitive to relevant changes in review protocol

We will deal with the most serious issue first. KadhimSaleh et al. excluded a study from one of our investigating team stating that “We further excluded Chow et al. [3] because it most likely included the same cohort as Chow et al. [4]”. this serious error would not have occurred if the reviewers were diligent in their processes. the published trial reports clearly stated that one cohort was recruited in 1998 and 1999, and the other cohort recruited in 2002–2003. Rather than contacting the trial authors to resolve uncertainty about the cohorts, which is normal practice for systematic reviewers Kadhim-Saleh et al. decided to base their decision on guess work, clearly not stringent reviewing practice. the hopefully unintentional insinuation that Chow and colleagues duplicated a cohort and included these duplicates as if they were separate cohorts in a subsequent meta-analysis published in the Lancet should be retracted. Kadhim-Saleh et al. criticize our previous meta-analysis because “... investigators included trials that used different and more subjective tools for assessing the primary pain outcome measure. p2494”. In fact we included studies that used several well-recognized and validated scales for pain assessment. this included calculating weighted mean difference for continuous data from visual analogues scale (VAS) scores for pain intensity, relative risk for dichotomized data for global improvement, and standardized mean difference to combine different validated scales of disability including the Neck Disability Index, Neck Disability Scale and the Northwick Park Questionnaire. this enabled us to conduct a comprehensive analysis of the available evidence and we believe that our finding that the results were consistent across the different measurement tools strengthened the robustness of our conclusion. Kadhim-Saleh et al. used a single outcome measure at a single time-point as their only outcome measure of success. We are concerned Dear editor,