Table 4 Final list of variable attributes and levels in the DCE
Attribute | Levels | Rationale |
|---|---|---|
1. Systolic blood pressure | a. 140 mm/Hga b. 185 mm/Hg c. 200 mm/Hg | • Highest ranked attribute in Stage 3 phases 1 and 2 • Levels include those across rage from ‘safe to offer thrombolysis’ to ‘grey are’ to ‘outside the thrombolysis licencing guidelines’ |
2. Gender | a. Malea b. Female | • To increase clinical face validity • To examine if gender has an unconscious influence on decision-making |
3. Age | a. 68a b. 85 c. 95 | • Included for purposes of ecological and face validity • Evidence from exploratory work that some clinicians may take patient age into account and adhere to current licensing guidelines |
4. Frailty | a. you do not perceive as fraila b. you perceive as frail | • Very challenging to adequately define frailty due to subjectivity in how clinicians view/consider it • Aim was to trigger perception of frailty in patient and therefore the current phrasing was considered optimal to meet aim |
5. Time since symptom onset | a. 50 mina b. 2 h 30 mins c. 4 h 15 mins | • Potential greater benefit of very early treatment time (50 mins) included to compare to mid-point in time window and rapidly approaching end of window (4 h 15mins) |
6. Pre-stroke dependency (mRS) | a. mRS 1 b. mRS 3 c. mRS 4a | • Qualitative work suggested mRS 3 was the grey area in dependency |
7. Pre-stroke cognitive functioning | a. No history of memory problemsa b. Moderate dementia c. Severe dementia | • Exploratory work suggested dementia/cognitive functioning could influence decision to offer thrombolysis |
8. Ethnicity | a. whitea b. Afro-Caribbean c. Asian | • Included as an attribute that may have an implicit effect on decision-making • Included as this is information that would be obvious in a typical decision |
9. NIHSS (stroke severity) | a. NIHSS 2 (without aphasia)a b. NIHSS 2 (with aphasia) c. NIHSS 5 (without aphasia) d. NIHSS 5 (with aphasia) e. NIHSS 14a f. NIHSS 23 | • Presence or absence of aphasia deemed very important in previous stage and therefore was included at lower NIHSS scores (mild strokes) to assess whether it would influence decision-making. • NIHSS 14 included as it is the SITS mean score (for treated patients) • NIHSS 23 considered a severe stroke |