Severe community acquired pneumonia
Authors: Graham D Mills, Richard Laing
Journal: BMJ (2006)

Research into community acquired pneumonia over the past two decades has focused on developing tools to measure the severity of illness and which antibiotics to choose. Several tools can now help clinicians identify patients with severe community acquired pneumonia in clinical settings.1 In people with severe disease, international guidelines recommend early treatment with broad spectrum antibiotics, which provide cover for atypical pathogens.2

It is less clear how best to manage patients during their stay in hospital. In this week's BMJ, a randomised trial by Oosterheert and colleagues reports the effect of switching from intravenous to oral antibiotics after three days rather than seven days in people with severe community acquired pneumonia.3 Until now, the lack of quality trial data in areas such as route of antibiotic administration, duration of treatment, and assessment of clinical stability has led to a conservative approach to management and prolongation of hospital stay. 

The National Health Service spends more than £400m (€592m; $780m) a year on community acquired pneumonia.4 To reduce healthcare costs, length of hospital stay should be reduced without compromising patient safety. Our group has shown that clinicians' behaviour is the main determinant of variability in the duration of treatment with intravenous antibiotics. It outweighs all other factors, including patient characteristics, and is therefore the major determinant of length of hospital stay for patients with this disease.5 Provision of quality data is key to reducing the pronounced variability in clinical practice. 

The trial by Oosterheert and colleagues provides more support for an early switch from intravenous to oral antibiotics. It found that such a switch was safe and reduced length of hospital stay (9.6 v 11.5 days; 95% confidence interval 0.6 to 3.2).5 One strength of the study was that it used clinical stability as the basis for switching from intravenous to oral treatment in the intervention arm. The time chosen to switch patients from intravenous to oral antibiotics was three days if clinical stability criteria were met (including respiratory rate <25 per minute, haemodynamic stability, and ability to take oral drugs). Data on the minimum safe duration of intravenous antibiotics in this context are still to be determined. During follow-up, only 2% of patients who were switched to early oral antibiotics needed to restart intravenous therapy. 

The other aspect of the study relevant to length of stay was the delay of about five days to discharge despite patients meeting predefined discharge criteria. This occurred even though the discharge criteria were more conservative than the stability criteria used for the intravenous to oral switch. The treating physician decided the time of discharge, and this decision will have been influenced by social factors and comorbidities specific to each patient. The authors suggest that incomplete resolution of all clinical signs of pneumonia delayed discharge even when patients were clinically stable. However, several observational studies found no advantage of observing inpatients once stability criteria comparable to those used in the current study were met.6 7 This suggests that the current study used overly conservative discharge practices, and it would have been safe to shorten length of stay further for most patients. However, patients must be stable before discharge, as adverse outcomes have been reported in people discharged with clinical instability.8

The challenge now is to design a new era of multicentre studies for community acquired pneumonia. Rather than continuing to search for the best antibiotic regimen, it is time to answer more pragmatic questions. Firstly, what degree of clinical stability needs to occur before switching to oral antibiotics given the pharmacokinetics and recognised modes of action of these drugs?9 If most (81%) patients safely tolerated the switch from intravenous to oral antibiotics after three days then some may have tolerated the switch earlier; possibly at the first sign of clinical improvement or even after the first dose. Secondly, would further investigation of the criteria for clinical stability, combined with strategies that deal with social determinants, facilitate further reductions in length of stay without compromising patient safety or satisfaction? We have sufficient evidence to ensure that research into these questions is ethical. 

The results of the study should give clinicians the confidence to switch clinically stable patients from intravenous to oral antibiotics at 72 hours, with consideration of early discharge thereafter. The traditional one size fits all approach to the management of community acquired pneumonia can no longer be justified.