Table 3 Fixed attributes used in DCE and rationale for inclusion
Attribute | Rationale for inclusion | Fixed level | Rationale for level |
|---|---|---|---|
Blood glucose level | Variable levels may result in diagnostic uncertainty | 6 mmol/L | Average blood glucose level based on SITS data of treated patients |
CT scan text description | To avoid skill/subjectivity around interpretation of scans | CT scan was conducted and is consistent with ischaemic stroke; it shows no haemorrhage or new ischaemic changes | Decided not to include image due to potential variability in CT image interpretation skill and subjectivity; difficulty finding scans to match multitude of various patient characteristics. Text description deemed most appropriate to remove diagnostic uncertainty |
To ensure confirmation of diagnosis of acute ischaemic stroke | |||
Anticoagulation status | While it was deemed an influential attribute, only minority of stroke patients take an anticoagulant and therefore it was not included as variable attribute | patient is not on anticoagulation therapy | To avoid any issues surrounding INR levels that could complicate the decision to offer thrombolysis |
Bleeding risk / recent surgery | Only relevant for a minority of patients. Challenging to operationalise variable and comparable levels in vignettes | no recent history of major bleeding | |
Diabetes | Not ranked as important in vignettes | no history of diabetes | |
Included as fixed attribute for clinical validity | |||
Patient consent/ family assent | assume either patient consent of family assent is available for treatment | ||
Other / Comorbidities | there are no other attributes which would deter treatment | Due to difficulty defining fully and generating comparable and feasible levels of comorbidities. Potential overlap with pre-stroke cognitive and pre-stroke dependency status | |
Fixed attributes included post-pilot testing (Stage 4) | |||
Handedness of patient | “All patients are right-handed” | To clarify and ensure the deficits will be interpreted consistently across all level of stroke severity (NIHSS) | |
Licenced dose bolus preparation time | “can be prepared for administration within 5 min” | Pilot testing revealed that participants would attribute in variable times in their decision-making so stating this will help control this potential error | |