Risk of bias tool for non-randomized studies and guidance on how to use it:
Publications of the Methods Group:
Reeves, B. C., Higgins, J. P. T., Ramsay, C., Shea, B., Tugwell, P. and Wells, G. A. (2013), An introduction to methodological issues when including non-randomised studies in systematic reviews on the effects of interventions. Res. Synth. Method, 4: 1–11. doi: 10.1002/jrsm.1068
Higgins, J. P., Ramsay, C., Reeves, B. C., Deeks, J. J., Shea, B., Valentine, J. C., Tugwell, P. and Wells, G. (2013), Issues relating to study design and risk of bias when including non-randomized studies in systematic reviews on the effects of interventions. Res. Synth. Method, 4: 12–25. doi: 10.1002/jrsm.1056
Valentine, J. C. and Thompson, S. G. (2013), Issues relating to confounding and meta-analysis when including non-randomized studies in systematic reviews on the effects of interventions. Res. Synth. Method, 4: 26–35. doi: 10.1002/jrsm.1064
Norris, S. L., Moher, D., Reeves, B. C., Shea, B., Loke, Y., Garner, S., Anderson, L., Tugwell, P. and Wells, G. (2013), Issues relating to selective reporting when including non-randomized studies in systematic reviews on the effects of healthcare interventions. Res. Synth. Method, 4: 36–47. doi: 10.1002/jrsm.1062
Schünemann, H. J., Tugwell, P., Reeves, B. C., Akl, E. A., Santesso, N., Spencer, F. A., Shea, B., Wells, G. and Helfand, M. (2013), Non-randomized studies as a source of complementary, sequential or replacement evidence for randomized controlled trials in systematic reviews on the effects of interventions. Res. Synth. Method, 4: 49–62. doi: 10.1002/jrsm.1078
Wells, G. A., Shea, B., Higgins, J. P., Sterne, J., Tugwell, P. and Reeves, B. C. (2013), Checklists of methodological issues for review authors to consider when including non-randomized studies in systematic reviews. Res. Synth. Method, 4: 63–77. doi: 10.1002/jrsm.1077