Marjon Borgert

122 Chapter 6 Number of elements per bundle The total number of elements per bundle varied, with a range of three elements in the central line bundle 36 to 11 in the sepsis bundle (Supplementary File 4). 68 The concept of a care bundle is to have a small number of elements to ensure that evidence based care will be delivered reliably. 4 Adding more elements is likely to a ect the reliability of the bundle, i.e. if more elements are included, it is more di cult to perform all bundle elements at once. Consequently, this results in lower compliance levels. 4 Di erences in types of bundle elements Our results show that even within one group of bundles, di erent types of elements were added. Hospitals design their own care bundle and when including elements, it is important that each element is generally accepted by hospital sta . 4,8 The reliability of these new elements, as well as the acceptance of an element (intervention), may a ect the likelihood and motivation to use the bundle. 3,4 One study compared the compliance rates of three di erent sepsis bundles. In this comparative study several factors were observed which were a ecting the compliance rates, such as the exclusion criteria for an intervention and the de nition of an intervention. 77 Time period compliance calculation Our results show that four di erent types of measurements were used to calculate the compliance levels. In most studies detailed information about compliance rates was not reported at all. In most studies the AON approach was used 4-6 , and therefore, it is possible that lower compliance levels were reported. Compared to the AON approach, the composite measurement has greater sensitivity for giving insight in the changes in care processes. 24,25 Benneyan recommends bothmeasurements because of their speci c bene ts. 24 In some studies the bundle compliance was measured monthly, while other studies measured compliance over a longer period of time, i.e. over a period of several months or years. In most studies detailed information about compliance, such as the monthly numerators and denominators, were not reported. Among the included studies, the success of bundle implementation was highly variable, even when studies were strati ed on design, methodological quality and type of measurement. This could be explained by either the number and types of bundle elements or by the ways compliance is measured and calculated as shown in this systematic review. Di erences in measuring and reporting performance outcomes were observed by Dixon-Woods et al. . 78 In their analysis of a national program to reduce the rates of central-venous-catheter-related bloodstream infections, they found that the