We presented data for random-effects models throughout because of the different demographic characteristics, measurement methods, and study durations that were involved in the original trials.
In order to provide support for our decision on how conclusive the reported results of a study are, we added the following categories: study sample, study duration, method of data collection, and outcome.
Study duration, dosing methods, data quality, guideline adherence, and sex were additional parameters for data filtering.
Heterogeneity was noted among studies in patient selection, definition of spine pain, scope of costs compared, study duration, and methods to estimate costs.
Significant heterogeneity remains in the initial inclusion criteria, staging and restaging methods, study design, timing of assessment, duration and rigour of follow-up of the trials reviewed — all of which obscure the validity of the results.
Ethical considerations of the study included the methods and tools used, aim of study, duration of the intervention, obtaining oral informed consent, confidentiality of information, and participants' right to withdraw from the study at will.
Two authors independently extracted treatment, sample size, drop-out rates, study duration, and statistical method used to handle missing data from all articles and resolved disagreements by consensus.
Second, we evaluated the spatial scale and temporal duration of studies and how study duration varied among research methods.
However, as mentioned by Young et al., 2009, the ideal ratio of BMP to VEGF depends on particular animal models, study duration, delivery matrixes, and assessment methods [ 11].
