Advancing convergent mixed methods design using the Diamond Approach for clinical multiple case studies: an example using data on time to treatment in aneurysmal subarachnoid haemorrhage

Using a new approach to the analysis and synthesis of a clinically focused mixed-methods multiple case study of aneurysmal subarachnoid haemorrhage (aSAH), we explored barriers and facilitators to timely treatment. In this paper we provide guidance for the multiple steps of analysis and synthesis of qualitative and quantitative data from across and within 27 case studies. Results showed that median (IQR) time to treatment was 15.1 (9.0, 24.1) hours. Only 37% of cases had treatment within 12-hours of onset. Early recognition of aSAH, good coordination, and availability of resources for treatment were main facilitators for treatment within 12 hours from onset. Lack of recognition of aSAH at onset and lack of resources for immediate in-hospital treatment were major barriers.