(i) → | Stepped wedge design has features of cluster randomisation, i.e. during a specific time period only type of intervention (usual care or HEART score) is administered |
       a. → | This reduces the risk of contamination |
       b. → | The effect of clustering needs to be taken into account in the statistical analysis |
(ii) → | Stepped wedge design has features of a one direction cross-over trial, i.e. each hospital contributes data from both usual care and HEART score in a fixed order. |
       a. → | Allows for comparison of results within hospitals which may be less confounded by differences in case mix than between hospitals |
       b. → | The fixed order from usual care to HEART score further reduces the risk of contamination as the HEART score is relatively simple to calculate. |
       c. → | Due to the cross-over, each hospital will provide data about the (problems in) implementation of the HEART score |
(iii) → | Switch from usual care to HEART score in hospitals is evenly and randomly distributed over calendar time |
       a. → | This reduces the impact of potential changes over time in other factors than the intervention |
       b. → | It facilitates the close monitoring and logistic of all activities surrounding the switch |
(iv) → | Gradual implementation of new strategy is carried out, thereby providing data about the process itself. |