Unpacking the Bundle to Lower Rates of Ventilation-Associated Pneumonia: Parts May Be Less Than the Sum

The concept of a bundle as away to implementmultiple best practices together to support quality improvement and better patient outcomes has great appeal.1,2 However, little is known about how bundles work and whether the individual components or the group are most important to care improvement. In this issue of JAMA Internal Medicine, Klompas and colleagues3 demonstrate that individual components of a bundle to lower rates of ventilator-associated pneumonia may have different effects on the outcome. Bundles are a key component of several large-scale improvement collaborations.1,2 In general, the bundling concept encourages complete adherence to a set of best practices that should be administered to every patient, every time. In many ways, the bundle parallels the use of checklists as an approach to standardizing care in a clinically useful and team-oriented approach. Components of care bundles are chosen based on best available evidence, ideally derived from high-quality randomized clinical trials. Even if individual components vary in terms of strength of evidence, a key aspect of bundling is that the whole of the bundle is greater (potentially) than the sum of its parts. Synergy of the components, or even the overall effectiveness of the bundle, could result because the effort put into implementing a bundle galvanizes other critical changes in care teams, communication, or organizational priorities important to improving patient outcomes. Alternatively, the bundle approach could be a key precondition for an implementation (and, potentially, measurement) strategy, including education, audit and feedback, and process redesign. Evidence of the effectiveness of the bundle approach in prevention of ventilator-associated pneumonia is marked by anumberof single-sitequality improvement studies anda few multicenter implementation reports; individual reports suggest substantial cost savings and the potential for reduced harms.4,5 However, few studieswere performed in an experimental fashion, and even fewer adhered to standards for reporting quality improvement programs.6 As a result, although the approach of bundling of care practices for prevention of ventilator-associated pneumonia is very likely associatedwith better patient outcomes, how it achieves this result is unclear.7 An important aspect to interpreting and planning studies of bundles is that eligibility for and adherence to bundles in itself incorporates a subtle mix of biases and confounding. For example, patientswho receive all aspects of a bundlemay be less sick or have less complex illness than those who do not or simply may have survived long enough to receive the bundle. In some cases, use of a bundlemay shorten or reduce the need for the underlying care process (in this case, mechanical ventilation), which in turn reduces the risk for adverse outcomes. The study by Klompas et al3 suggests that the benefits of full bundle compliance might be greater than what would be anticipated fromthe sumof the individual components,many ofwhichhad limitedassociationwithpatientoutcomes in their study. This observation is worth further consideration. Although any single-site study will inevitably raise questions about generalizability, unlikemultiple-hospital studies, their resultsarenotbiasedbyotherhospitalpractices thatmightalso be associatedwithhigher levels of bundle compliance. For example, inamulticenter study,patients treatedathospitalswith higher bundle compliancemight also benefit frombetter care in general, including difficult-to-measure aspects like teamwork and communication. Patients in this study who received bundle elementsmay be systematically different from thosewhodidnot (thehealthyuser biaswedescribed above). Although the authors adjusted for multiple potential confounders, adjustment was limited to observed confounders. A limitation of the study is that the authors did not provide data comparing patients who received the bundle with those who did not, raising the possibility that other factors— clinical, health care professional–related, or system-level— could partially explain their findings. The clinical implications of varied tono associationswith outcomes and theneed to report bundle compliance at thepatient or hospital level are substantial. Thus, another limitation of the study is that the results do not clarify whether individual components didnot lead tobetter outcomesbecause of limited biological effectiveness in reducing ventilatorassociated pneumonia risk, orwhether implementation challenges were to blame. For example, even if supported by randomized clinical trial data, a bundle approach may have producedchanges indocumentationandtheappearanceof improved practice but not clinical practice.8 Second, how to interpret differingmagnitudes of association between individual components and their key outcomes remains unclear. Should these factors be considered additively important?Or should interactionsandsequencesbeemphasized? For example, does the effect of oral care and headof-bed elevation depend on whether they are performed together rather than separately? Finally,andperhapsmost important, lackof focusonevaluation of the bundle componentsmay be an impediment to the evolutionof thebundle itself.To thispoint,discerningwhether Related article page 1277 Research Original Investigation Associations Between Ventilator Bundle Components and Outcomes