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Barcelona, Spain
Dr. Torres is Chief of Pulmonology and Critical Care Department, Clinical Institute of Thorax, Hospital Clinic, IDIBAPS, Red Gira and Red Respira, Facultat de Medicina, Universitat de Barcelona.
Correspondence to: Antoni Torres, MD, Servei de Pneumologia, Hospital Clínic Barcelona, Villarroel 170.08036, Barcelona, Spain; e-mail: atorres{at}ub.edu
Is There a Clinical Impact on Outcome?
Hospital-acquired pneumonia (HAP) is a common and serious clinical problem. In fact, it is the second most frequent nosocomial infection and the first in the ranking of mortality. The incidence of HAP acquired outside the ICU has recently been studied by Sopena et al1 in a multicenter study reporting an incidence of 3 ± 1.4 per 1,000 hospital admissions and a crude mortality of 26% (14% of attributable mortality). Ventilator-acquired nosocomial pneumonia (VAP) is a form of HAP that develops during mechanical ventilation. The overall incidence ranges from 9 to 27% of intubated patients, accounting for a very high attributable mortality (range, 33 to 50%). This variability in the incidence and mortality of VAP reflects the different populations studied, the different methods used for diagnosis, as well as the different methods and prevention programs implemented.23
There are some medical interventions that can modify the outcome of HAP and VAP. The most effective intervention is early and appropriate administration of antibiotics.45 Initial appropriate antibiotic treatment is associated with lower mortality, shorter length of stay, and lower number of complications.4 Multidrug-resistant (MDR) microorganisms are responsible for a great proportion of inadequate initial treatments.4
The protocolization of the management of diseases is a key issue in modern medicine and should be carried out following evidence-based recommendations. In the last 10 years, several guidelines have been published on respiratory infections such as community-acquired pneumonia, COPD exacerbations, and HAP. The utility of these guidelines has been clearly demonstrated. For example, using a "before-and-after" design, Dean and colleagues6 showed a decrease in mortality (from 13.4 to 11%) after the implementation of the old American Thoracic Society (ATS) guidelines for CAP in a group of hospitals.
In the study published in this issue of CHEST (see page 2778), with the use of an observational cohort study with preguideline and postguideline data collection, Soo Hoo and colleagues7 studied the impact of the implementation of the 1996 ATS HAP guidelines8 in 61 episodes of severe HAP. Interestingly, implementation of the guidelines resulted in a higher percentage of adequately treated patients (81% vs 46%) and a lower mortality at 14 days (8% vs 43%). Appropriate imipenem use occurred in 74% of the cases with no increase in the imipenem-resistant microorganisms at the end of the study. This study confirms that the implementation of evidence-based protocols decreases the mortality in HAP. This type of study is absolutely necessary to convince health-care authorities and medical communities of the importance of providing resources for the development and implementation of guidelines. These communities are often more concerned with supporting basic science than guiding and correcting errors in clinical practice.
Several studies have validated the 1996 HAP guidelines. At least two studies910 have confirmed the validity of the ATS guidelines in terms of patient stratification and accurate prediction of potential microorganisms for empiric antibiotic treatment. In one retrospective study, Ioanas et al9 found correct prediction of microorganisms in 91% of the cases; most of the incorrect predictions were MDR microorganisms found in patients from the ATS group 2. The accuracy of prediction in the study by Leroy et al10 was 100% with the use of the ATS guidelines to exclude the presence of resistant pathogens in low-risk patients. These studies confirm the utility of the ATS guidelines, at least in terms of microorganism prediction.
Other studies have evaluated the impact on outcome after guideline implementation. Ibrahim and colleagues11 compared VAP patients before (n = 50) and after (n = 52) guideline implementation. This study used a modified version of the 1996 ATS guidelines recommending the initial use of imipenem plus ciprofloxacin and vancomycin. An adjustment of antibiotic treatment was specifically recommended. Ibrahim and colleagues11 found 94% of adequate initial antibiotic treatment in the period after guideline implementation compared to 48% before implementation. The length of treatment was reduced 6 days, and a second episode of VAP occurred less often in the after period (7.7% vs 24%). With regard to the length of treatment, in a prospective, randomized trial12 in a medical ICU, 150 patients were randomized to early discontinuation of therapy and 140 patients followed conventional therapy. Ninety-three percent of the patients were treated adequately in both groups, but the duration of therapy was significantly reduced with intervention (6.0 days vs 8.0 days, p < 0.001)
Several issues should be taken into account when implementing guidelines for HAP and VAP in a specific setting:
The new, recently published ATS/Infectious Diseases Society of America (IDSA) HAP guidelines3 are an important step forward in the management of HAP and VAP patients. The main focus and principles of the guidelines described at the beginning of the document summarize most of what is mentioned above: (1) avoid untreated or inadequately treated patients because the failure to initiate prompt appropriate and adequate therapy has been a consistent factor associated with an increased mortality; (2) recognize hospital-to-hospital variability, specific sites within the hospital, and one time period to another; (3) avoid the overuse of antibiotics by focusing on accurate diagnosis, tailoring therapy to the results of lower respiratory tract cultures and shortening the duration of the therapy to a minimal effective period; and (4) apply prevention strategies aimed at modifiable risk factors.
The new ATS/IDSA guidelines3 describe which specific risk factors may be associated with the potential presence of MDR microorganisms. This is an important issue that may improve our prediction and accuracy in covering MDR microorganisms. The main variables to stratify patients for empiric treatment in the new guidelines are the onset of pneumonia and the presence or absence of these risk factors, thereby simplifying the management of antibiotic treatment in HAP patients.
There are some issues from the study by Soo Hoo et al7 that deserve comment and may be of use in the design of future studies on guideline validation:
50% of cases15 and is also associated with higher mortality, length of hospital stay, and costs. However, death is not observed in all patients presenting treatment failure. Future studies should include a reduction in treatment failure as a desirable end point to be achieved on the implementation of guidelines. In summary, at least concerning respiratory infections, guideline implementation is necessary to provide the best medical care for our patients and to improve their outcome. Studies such as that published in the present issue of CHEST on guideline validation are necessary. Nonetheless, the optimal methodology to carry out these studies still requires standardization.
References
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