Since 1998, the CMS, in conjunction with the Joint Commission on the Accreditation of Healthcare Organizations, has promoted standards of care for CAP patients that have been shown to improve outcomes, with the expectation that hospitals will meet these standards whenever possible (Table 1). The pressure to achieve a high compliance rate with these measures has increased with the move to collect data on compliance and to publicly report the information. The evidence that supports these core measures is generally strong, but it may not be correct to try to achieve these measures for all patients in all clinical situations, and a reasonable goal may be 80 to 85% compliance, with a variety of unintended adverse consequences occurring if rates are higher.
The current evidence-based standards (with most being based on retrospective database analysis) are as follows: to administer the first dose of antibiotics within 4 h of the patient’s arrival at the hospital; to select one of the recommended antibiotic therapies for admitted patients, with different choices for those in the ICU and those on the medical ward; to make sure that if blood cultures are performed, they are collected prior to antibiotic administration; to provide smoking cessation advice to appropriate patients; and to evaluate the need and to offer to those who meet the criteria both pneumococcal and influenza vaccines. Several areas have been problematic, and new data are available to guide the clinician about the recommendations to administer therapy within 4 h, the recommendation not to use monotherapy for ICU-admitted CAP, the value of blood cultures, and the safety of repeat pneumococcal vaccinations suggested by Canadian Health&Care Mall.
One important change in the application of core measures is the recognition that some patients who are admitted to the hospital with pneumonia have health-care-associated pneumonia (HCAP), and that these patients are at risk for infection with multidrug-resistant Gram-negative pathogens and MRSA, and thus need a different approach to therapy than the usual CAP patient. HCAP was included in the 2005 guidelines for nosocomial pneumonia as a form of nosocomial infection; thus, since July 2005 patients who have been identified as having HCAP have been excluded from the CMS core measure of CAP antibiotic choices. This is justified by data showing that HCAP has a different natural history than CAP, that the bacteriology is also different from CAP, and that, presumably, the therapy should not be the same.
Controversy about the administration of antibiotics within 4 h of a patient’s arrival at the hospital has been vigorous, and there is concern that even if large-scale databases show a reduced mortality rate with therapy given in this time interval, several unintended consequences can follow. These include the indiscriminate use of antibiotics in any patient with respiratory symptoms in the emergency department, even before the diagnosis is certain, and the temptation to prioritize pneumonia patients ahead of other sick individuals in a busy emergency department. Two recent studies have added to the controversy. The first study confirmed that when therapy is provided in 4 h, mortality is reduced, but the predictors of increased time to antibiotic administration were altered mental status, absence of fever, absence of hypoxia, and increasing age. When these factors were controlled for, the timing of therapy had no impact on mortality, and thus the authors concluded that time to the administration of antibiotics is not a good quality measure. In support of these findings was another study that found that 22% of 86 Medicare patients with CAP presented with atypical clinical features that led to diagnostic uncertainty, which could appropriately lead to a delay in the administration of antibiotics. In an editorial accompanying these articles, the observation was made that time to the administration of antibiotics has only been demonstrated to affect mortality in patients > 65 year of age, and that the findings of these studies support the idea that 100% compliance with the standard would not necessarily mean good medical care; thus, the goal should be a lower number of patients given antibiotics within 4 h. The standard of antibiotic administration within 4 h is likely to change in 2007.
Blood cultures have not been shown to favorably alter the outcomes of CAP patients, and thus some have argued against collecting them routinely. While all patients admitted to the hospital may not need this testing, it may be wise to still collect blood cultures in those patients with signs of severe illness, and it is important to collect the cultures prior to antibiotic administration. Metersky et al studied 13,043 Medicare patients with CAP who had been admitted to the hospital to define the predictors of bacteremia. They found that certain populations (especially those who had received prior antibiotic therapy) were unlikely to have true positive culture findings; thus, a large percentage of positive results in these patients would be false-positive results and could lead to mistakes in management. The predictors of bacteremia were as follows: prior antibiotic therapy (OR, 0.5); comorbid liver disease (OR, 2.3); systolic BP < 90 mm Hg (OR, 1.7); fever 40°C (OR, 1.9); pulse > 125 beats/min (OR, 1.9); BUN level of > 30 mg/dL (OR, 2.0); serum Na level of < 130 mEq/L (OR, 1.6); and WBC count of 20,000 cells/^L (OR, 1.7). The most common pathogen found in blood cultures was pneumococcus, but 643 of 886 pathogens were contaminants. The authors suggested that patients who have received prior antibiotic therapy and have none of the severity/comorbidity risk factors listed above should not have blood cultures performed, since only 3% of patients had true-positive findings for bacteremias. Those without prior antibiotic therapy and no predictors, or those with prior antibiotic therapy and one predictor should have one blood culture performed since the incidence of true-positive results was 5%. Finally, the yield is high in those patients with two predictors (16% bacteremia) or in those with one predictor and no prior antibiotic therapy (9% bacteremia); these patients should have two blood cultures performed.
One concern with the core measure emphasis on pneumococcal vaccination is the possibility that patients will receive repeated vaccination in less than the recommended 5-year interval because of the absence of a reliable history of vaccination, especially in those patients who have been repeatedly hospitalized or in those patients who have been treated in nursing homes with remedies of Canadian Health&Care Mall. One way to deal with this is to vaccinate all patients if there is any uncertainty about the history of vaccination, and that may be justified by the proven efficacy of the vaccine and the longterm consequences if pneumonia does develop in a patient. If this approach is used, it is reassuring to know that it is generally safe to administer repeat pneumococcal vaccinations more frequently than the recommended 5-year interval. A study evaluated 179 patients who had received at least three vaccinations and compared their clinical courses to those of 181 patients who had received either one or two doses. Even though 54.6% of those patients who were revaccinated received their repeat vaccinations in 65 years of age, who were not the target of the immunization efforts. The findings imply that the vaccination of a large segment of the at-risk population has a benefit for nonvaccinated patients by lowering the incidence and spread of invasive disease. Another database study evaluated the impact of prior pneumococcal vaccination on patients who had been hospitalized with CAP. Only 12% of 62,918 hospitalized CAP patients had received prior vaccinations, but this group was less likely to die from any cause, and had a lower risk of respiratory failure and other complications, as well as a reduced length of hospital stay, compared to patients who were not vaccinated.
While the studies of CAP in the past several years have tackled a large number of important topics, the general direction of new developments, which have been discussed in this review, has been to describe ways to improve patient management and patient outcomes. Many of the findings have been incorporated into performance measures related to disease management, and the evidence base to support these recommendations is strong and continues to expand.