After compiling the necessary data, the goal of this step is to answer the initially posed research question as defined in the protocol. For this, all review authors should come together, ideally with knowledge about the extracted data and the overall risk of bias of eligible studies. Several consensus rounds among study authors might be required to draw a conclusion.
If defined in the protocol, now is also the time to conduct a sensitivity analysis to determine the robustness of the conclusion(s). The idea of a sensitivity analysis is to determine whether the same conclusions can be drawn with an altered dataset, e.g., by only including studies with lower risk of bias or only including larger studies.
Of note, it is possible that the initially posed research question cannot be answered by the available evidence. However, in such a case, the heterogeneity of the field can still be probed and important insights into about what is known and what is not known can be gained. This can help to clarify ambiguous research areas and understand the nature and causes of biological/clinical diversity.
Work in progress
You can use your overall conclusion to inform the summary assessment of certainty of the evidence, e.g., by using the GRADE approach.