The 4PPTP has been clinically tested across a multitude of experimental conditions. Results of these trials of the 4PPTP have shown increased uptake of seasonal influenza vaccine in children; (44-47) meningococcal and Tdap vaccines and HPV initiation and completion in adolescents; (77, 78) seasonal influenza, pneumococcal, and pertussis vaccines in adults; (42, 48, 79) and pneumococcal vaccines in older adults. (80) Moreover, each application of the program offered opportunities to improve the delivery of the intervention methods culminating in the systematic and scalable current version of the program.
The earliest version of the program was developed from an intervention to increase adult immunization rates among minority patients of inner-city health centers.(81) Investigators used a before-after design with four clinics and maintained a fifth site as a concurrent control. During the intervention period for each site, clinical staff were provided education on immunization in primary care and potential strategies for improvement sourced from systematic literature reviews. Each site selected strategies from a menu of options according to the staff’s perceived expectation of feasibility and effectiveness in their setting. Some examples of selected strategies were:
• Adoption of standing orders for vaccination • Hanging of reminder posters
• Looping video in waiting room
• Mailed reminders for immunization including a coupon for a free vaccine • Walk-in influenza clinic
Among a random sample of patients aged 50 years old or older (n=568), the influenza vaccination rate increased from 27.1% to 48.9% (P<.001) and the PPV rate increased from 48.3% to 81.3% by the conclusion of the program in intervention sites. In the control site, changes in these rates were minimal and statistically insignificant. Logistic regression analyses controlling for age, race and sex, showed that rates for older adults (>65 years old) improved the most and that non-white individuals benefitted as much as white individuals. These findings suggested that the intervention was successful in the population and especially effective in the most vulnerable and underserved sub-populations.
Having demonstrated success in older adults, Zimmerman et al. improved the program and tested its effectiveness to increase childhood influenza vaccination rates of primary care providers serving disadvantaged populations. (46) In this cluster randomized trial, twenty primary care practices were stratified by practice and patient characteristics and then randomized to intervention or control arms. Practices in the intervention arm received the intervention prior to the 2010-2011 flu season. Practices in the control arm were informed that their intervention would begin in the following season.
Preparation for this trial solidified the conceptual framework of the program. Insight gained during the previous effort led to two important changes in the program. First, the evidence-based strategies were organized into “The 4 Pillars” which emerged as: Pillar 1 – Convenient vaccination services; Pillar 2 - Notification of patients about the importance of immunization and the availability of vaccines; Pillar 3 - Enhanced office systems to facilitate immunization; Pillar 4 - Motivation through an office immunization champion. Second, the delivery of the intervention was orchestrated using Diffusion of Innovations theory. (82) These enhancements evolved from
careful observation of the behavior of clinicians and staff during program adoption and the need for standardized and repeatable intervention delivery methods.
During the initial trial, investigators observed that the intervention protocol appeared to have been enhanced by spontaneously emerging system dynamics. In the published discussion of the results, the investigators propose that the collaborative engagement of the clinical teams may have contributed to the emergence of an unexpected catalyst contributing to the improvement of immunization rates. Though this tactic was employed to elicit multicultural perspectives in strategy selection, it appears to have also stimulated enhanced engagement and/or adoption of the program. Even a decade later, this self-actualizing methodology remains novel among the more focused and prescriptive models of quality improvement centered on clinician education. Similarly, in reviewing the proposed evidence-based strategies, clinicians recognized that their practices would have to alter more than just the clinical encounter to maximize opportunities to vaccinate their entire patient panel. Thus, the scope of strategies selected by the sites included a much broader context than the single interaction with an unimmunized patient. Rather, clinicians chose to focus change on structural and organizational leverage points that engage the entire treatment team as well as the unvaccinated in cooperative solutions beyond simple patient education.
The awareness of these environmental contributors to program effectiveness required a new layer of complexity in the intervention. The 4 Pillars™ schema was developed to represent a taxonomy of strategies organized around influential processes in a larger perspective of preventive care. Each pillar captures a necessary-but-insufficient spectrum of processes that are associated with improved vaccination uptake. During implementation, clinicians were instructed to select strategies from each of the pillar domains so that the program remained manageable while still including all of the components necessary to produce measurable long-term results.
Likewise, the adoption of a theory-informed deployment strategy became necessary to strategically harness the amplifying effects of inter-clinician relationships. Diffusion of Innovations theory was a natural fit for this aim as it focuses on moving a large population toward behavior change through the early adoption of the desired behavior by a relatively small number of individuals. With reinforcement, more individuals adopt the behavior until a tipping point shifts environmental dynamics and the new norms become a more desirable state that further accelerating adoption.
As predicted, the intervention significantly elevated influenza vaccination rates in the pediatric population. Among patients aged 9-18 years, overall improvement was 9.9 percentage points in the intervention group vs 4.2 percentage points in the control group. Additionally, when controlling for patient and practice characteristics, likelihood of vaccination increased for non- white children in all age groups.(47) However, a more interesting finding appeared in a subsequent analysis of post-intervention maintenance. One year after completing the program, the intervention group maintained the gains achieved during the program and increased an additional 0.4 percentage points (P > 0.05) without any further contact from the study team.(44) This finding suggested that the intervention achieved a change in the system which persisted beyond the termination of the program.
Seeking to expand the reach, consistency and sustainability of the intervention, the research team initiated a larger multi-center trial. This cluster randomized trial was conducted in primary care practices in the Pittsburgh and Houston regions and targeted the improvement of specific vaccination rates in adolescents and adults. The expanded scope of required content, geographic distance and increased number of participant clinicians necessitated further enhancements to the
intervention protocol. With these enhancements, the program achieved significant reductions in missed opportunities to vaccinate adults leading to an improved vaccination rate. (83)
The cost effectiveness and potential public health impact of the program have also been calculated from the research data and reported for select scenarios in the US adult population. These evaluations, discussed below, report that the program is cost-effective and would likely deliver value at the population-level. (84, 85)
The 4PPTP is more than a theoretical framework for immunization improvement. The concepts discussed above have been integrated into a systematic and scalable intervention designed to be deployed with fidelity across a variety of primary care practices, organizations, and patient populations. This intervention methodology was concurrently developed with each increasingly complex clinical trial of the 4PPTP constructs. The most recent evaluations of the program, which will be discussed in subsequent chapters, measure effectiveness in real-world applications with teams who have adopted the program as a clinical care quality improvement effort rather than as participants in controlled laboratory conditions.