This study, as a preliminary result report of our ongoing systematic review, aims to enhance the understanding of factors influencing collective intelligence (CI) in medical co-design groups. The systematic review began with 3,087 relevant studies, narrowing down to 45 studies included after a detailed screening process. The factors discussed in this paper were extracted not only from the final 45 studies but from valuable findings throughout the entire screening process. Using a four-level hierarchy based on our previous CoX Model research, we identified and analysed key factors contributing to CI emergence. The findings highlight the significance of some key factors such as diversity in expertise, decentralisation, and effective information flow in enhancing the collective problem-solving abilities of design groups. The study reinforces existing theoretical models and provides practical insights for optimising team dynamics in medical design projects. These insights are crucial for improving the efficiency and innovation potential of design teams across various sectors.