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

Backgrounds and aims: Delays in treatment of aSAH appear common but the causes are not well understood. We explored facilitators and barriers to timely treatment of aSAH. Methods: We used a mixed-methods multiple case study approach including in-depth interviews with stakeholders involved in individual aSAH cases, focusing on events from onset to treatment. Quantitative data were extracted from medical records including date and times. Within-case analysis identified barriers and facilitators in 4 phases (pre-hospital, presentation, transfer, in-hospital), which then being triangulated with the quantified time in each phase to determine significant influencing factors. Finally, we conducted thematic analysis across cases in early ( 12h) treatment group using a case-study matrix. Results: Twenty-seven cases (74.1% female) with 89 interviewees were included. Median (IQR) time to treatment was 15.1 (9.0, 24.1) hours. Only 37% of cases had treatment within 12 hours of onset. Qualitative and quantitative data triangulation identified key themes influencing timely treatment of aSAH. Early recognition of aSAH and good coordination during pre-hospital and diagnosis phases, and availability of resources for treatment during in-hospital period 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 for more delayed treatment. Conclusions: Using a robust mixed-methods approach, we identified the most significant factors affecting more timely treatment within 12 hours from onset of aSAH. The factors are potentially modifiable and may improve timely treatment of aSAH.