A quantitative synthesis, or meta-analysis, uses statistical techniques to combine and analyze the results of multiple studies. The feasibility and sensibility of including a meta-analysis as part of your systematic review will depend on the data available.
Requirements for quantitative synthesis:
Examples of Meta-Analyses
Urquhart, O., Tampi, M. P., Pilcher, L., Slayton, R. L., Araujo, M., Fontana, M., Guzmán-Armstrong, S., Nascimento, M. M., Nový, B. B., Tinanoff, N., Weyant, R. J., Wolff, M. S., Young, D. A., Zero, D. T., Brignardello-Petersen, R., Banfield, L., Parikh, A., Joshi, G., & Carrasco-Labra, A. (2019). Nonrestorative Treatments for Caries: Systematic Review and Network Meta-analysis. Journal of dental research, 98(1), 14–26. https://doi.org/10.1177/0022034518800014
McLenon, J., & Rogers, M. (2019). The fear of needles: A systematic review and meta-analysis. Journal of advanced nursing, 75(1), 30–42. https://doi.org/10.1111/jan.13818
Salluh, J. I., Wang, H., Schneider, E. B., Nagaraja, N., Yenokyan, G., Damluji, A., Serafim, R. B., & Stevens, R. D. (2015). Outcome of delirium in critically ill patients: systematic review and meta-analysis. BMJ (Clinical research ed.), 350, h2538. https://doi.org/10.1136/bmj.h2538
Jim, H. S., Pustejovsky, J. E., Park, C. L., Danhauer, S. C., Sherman, A. C., Fitchett, G., Merluzzi, T. V., Munoz, A. R., George, L., Snyder, M. A., & Salsman, J. M. (2015). Religion, spirituality, and physical health in cancer patients: A meta-analysis. Cancer, 121(21), 3760–3768.
Henry, B. M., de Oliveira, M., Benoit, S., Plebani, M., & Lippi, G. (2020). Hematologic, biochemical and immune biomarker abnormalities associated with severe illness and mortality in coronavirus disease 2019 (COVID-19): a meta-analysis. Clinical chemistry and laboratory medicine, 58(7), 1021–1028. https://doi.org/10.1515/cclm-2020-0369
Frauenknecht, J., Kirkham, K. R., Jacot-Guillarmod, A., & Albrecht, E. (2019). Analgesic impact of intra-operative opioids vs. opioid-free anaesthesia: a systematic review and meta-analysis. Anaesthesia, 74(5), 651–662. https://doi.org/10.1111/anae.14582