In the past decade, the focus of infection control practice has switched from surveillance to interventions.1,2 The combined application of measures (collectively referred to as "bundles") aimed at prevention and control of healthcare-associated infections (HCAI) has been extensively studied.3–5

In this setting, there are concerns over the energy and time spent in applying simultaneously several bundles directed at different sites of infection.6 Furthermore, the successful results in some reports may have been biased by short-time post-intervention follow-up. Short-run results may imply statistical variations around the historical average.7 Finally, since monthly rates of HCAI are not independent among themselves, usual statistical tests (such as Chi-square, Student’s T and ANOVA) are not appropriate for detecting changes in incidence before and after interventions.8,9

Therefore, we studied the impact of a bundle aimed at preventing ventilator-associated pneumonia (VAP) on the incidence of overall and device-associated infections in adult medical-surgical intensive care units (ICU) in a Brazilian hospital.

Complete adherence to the bundle was 53%. Adherence to specific items was above 80% in most surveillance instances, except for daily interruption of sedation. The ICU staff was reluctant to implement this measure, so adherence remained around 50%.

The overall HCAI rate during the study period was 37.71 per 1000 patient-days. The proportions of infectious sites were: VAP, 43.5%; bloodstream infection (BSI), 20.3%; catheter-associated urinary tract infection (CAUTI), 18.8%; other sites, 17.4%.

Pre- and post-intervention HCAI rates in the included ICU and use of invasive devices are presented in Table 1. It should be pointed out that the original goal of the VAP bundle was achieved in both ICU. Tables 2 and 3 present results from multivariate Poisson models of ITS for HCAI and use of invasive devices, respectively. Briefly, ITS models documented the impact of the intervention on overall HCAI (in ICU #1), VAP and BSI (in both ICU). The ITS graphics are presented in Fig. 1.

Fig. 1.

Interrupted time series graphics for time trends of healthcare-associated infections in two medical-surgical intensive care units before and after the implementation of a bundle aimed at preventing ventilator-associated pneumonia.

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In recent years, HCAI have been recognized by the World Health Organization [WHO] as a major threat for public health, especially in developing countries.14,15 In our study, we faced the challenge of reducing VAP in a resource-limited and understaffed setting.16 Not surprisingly, our team encountered nihilistic attitudes from ICU staff. This challenge was managed with continuous education during visits of infection control nurses to the ICU to perform surveillance and measure adherence to the bundle.

The positive impact of bundles in preventing VAP (or, more recently, “ventilator-associated events”) has been reported by several authors,17–20 with few exceptions.21 The serendipity in our results was that improved surveillance for adherence to the bundle seemed to impact on the incidence of other HCAI. It is worth noting that there were no changes in policies for prevention of other device-associated infections during the study period.

Recent emphasis has been placed in socio adaptive approaches to improve adherence to infection control practices.22 Positive deviance, link nurses, behavioural economics and social network interventions have been tested, often with positive results.22–24 Our argument is that even simple measures which reinforce the presence and interaction of infection control team with other HCWs can improve safety culture, with widespread beneficial approach. Naturally, that interaction can be improved by more robust theory-laden approaches.22 One should notice that adherence to the whole bundle was only moderate, but we still achieved reduction in VAP and other HCAI rates. So, the bundle itself does not fully explain our results. We hypothesize a phenomenon similar to the so-called “surveillance effect”, in which adherence to a national surveillance system leads to decrease in HCAI incidence.25 In both cases, there is mobilization of infection control and other healthcare workers towards improving outcome indicators.

Our results also reinforce the importance of using ITS methods, instead of comparing “before and after” rates. The latter approach is suboptimal, since tests like Chi-square, Student’s t-test and others were developed for comparing independent variables, and adjacent time periods do not meet the criteria of statistic independence.8 Furthermore, impacts on time trends may be lost or even misunderstood.9 Finally, ITS requires long-term follow up, which is appropriate to identify sustainable impact of interventions.

As a secondary finding, there was evidence of seasonality for central-line associated bloodstream infection (CLABSI) in ICU #2, a finding in line with our previous studies.26,27 Finally, trends of use of invasive devices before and after the intervention may vary towards increasing or diminishing.

Our study has some limitations. First, over such a long period, it is evident that the infection control team performed continuous normative and educational measures, which possibly reinforced the prevention of HCAI. However, there was no other strong point intervention, so we believe that our premise that VAP bundle had a wide impact in infection control remains valid. Indeed, the continuous visits necessary for observing adherence to items of the bundle probably increased the proximity between infection control nurses and the ICU team. Second, we targeted the “old-fashioned” VAP, using diagnostic criteria often described as subjective.12 However, using this stable definition allowed us to study a long-term time series. Also, the impact of our intervention was noticed in the much more objectively defined CLABSI. Third, adherence to hand hygiene was continuously measured only after year 2016. This information was missing for most of the study period, and therefore could not be included in our model. Data on individual severity-of-illness was not included in the analysis. It should stressed that both hospital administrative data and information collected in previous studies from our group27 found no variation of severity-of-illness of patients in the evaluated ICU. Finally, the methodological design of this study shares the usual limitations of ecologic epidemiological approaches (mainly not adjusting for individual-based factors). Still, ecologic studies are the most appropriate methods for addressing collective exposures and/or interventions.28 Other strengths of our study include using ITS and the long-term follow up of the intervention. In developing countries, where structure for infection control is often suboptimal,15,29 intensification of interventions and the appropriate analysis of their results may be especially useful for improving patient safety.

In conclusion, we found that a partially successful implementation of a bundle aimed at reducing VAP resulted in long-term, positive impact on overall HCAI, VAP and CLABSI. Novel and continuous approaches may result in further improvement.

The author declares no conflicts of interest.