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Table 3 Overview of key characteristics of the stepped wedge design

From: The impact of the HEART risk score in the early assessment of patients with acute chest pain: design of a stepped wedge, cluster randomised trial

(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.