Guidelines for the management of community ... - Brit Thoracic

BTS guidelines
45 [III]
those under 65 years of age and 7.8 days for older patients.
A prospective study of costs and outcome of CAP from five
hospitals in North America concluded that costs of antibiotic
therapy varied widely but had no effect on outcome or
mortality. Patients treated in the hospitals with the lowest
46 [Ib]
costs did not have worse medical outcomes.
Summary
c The direct costs associated with CAP are high and mostly
associated with inpatient care costs. [III]
c Substantial costs savings could likely be made by strategies
to prevent CAP, to reduce the requirement for hospital
admission and to shorten the length of hospital stay. [III]
2.4 What comments can be made about cost effectiveness of
different therapies?
We are not able to provide any structured guidance on this
subject. Modern guidelines should attempt to provide information,
not only on clinical management but also on the assessment
of robust published data on cost effectiveness of therapies.
However, it was noted that there is a clear deficiency of good
quality comparative clinical data which would allow meaningful
comparisons of management and antibiotic strategies for CAP,
whether assessing for clinical or cost effectiveness outcome.
Summary
c We have not attempted a systematic appraisal of current
pharmacoeconomic evidence for CAP and do not give a
structured view on cost effectiveness.
c Cost effectiveness data pertinent to UK practice does not
exist at the time of writing and is an area for further
research.
SECTION 3 AETIOLOGY AND EPIDEMIOLOGY
3.1 Introduction
No two studies of the aetiology of CAP are the same. Apparent
differences in the observed frequency of pathogens, while
possibly real, may also be due to a number of other factors
including healthcare delivery (distribution of management
between primary and secondary care, hospital and ICU
admission practices), population factors (such as age mix, the
frequency of alcoholism, comorbid diseases, immune suppression
and malignancy) and study factors (type and number of
samples collected, investigations performed, result interpretation).
Frequently, such details are not explicitly stated in the
study methodology and, although we have not included studies
which do not comply with certain standards, apparently similar
studies may hide very different methodology. With the
exception of elderly subjects, few adequately powered studies
using the same methodology have been used to compare
different population groups. Conclusions about observed
differences in the following data must therefore be treated
with caution.
Many of the statements in the following text arise from a
comparison of studies, rather than data from individual studies
that have set out to answer that question. For this reason,
evidence grades follow statements to justify that conclusion, as
well as individual references.
3.2 What are the causes of adult CAP in the UK?
These are set out in table 2, together with details of the relevant
references (and grading of evidence from those individual
iii12
references), grouped together by where patients have been
managed—be it in the community, in hospital or on an ICU. For
all these groups, a common range of pathogens is regularly
identified as causes of CAP. [Ib] Although a single pathogen is
identified in 85% of patients where an aetiology is found, the
true frequency of polymicrobial CAP is not known and observed
figures are dependent on the intensity of investigation. S
pneumoniae is the most frequently identified pathogen. [Ib] The
relative frequency of pathogens in patients managed in the
community and in hospital is probably similar, but the absence
of more than one study in the community makes further
conclusions uncertain. Legionella species and S aureus are
identified more frequently in patients managed on the ICU.
[Ib] The apparent difference in the frequency of Mycoplasma
pneumoniae may depend on whether or not a study is performed
in an epidemic year. [II] Gram-negative enteric bacilli,
Chlamydophila psittaci and Coxiella burnetii are uncommon
causes of CAP. [Ib]
Since 2001 only one additional study of adults admitted to
hospital with CAP has been published, 47 which found a similar
distribution of common causative pathogens to that in previous
studies.
3.3 What are the causes of adult CAP in similar populations
elsewhere in the world?
The results and references of relevant studies from the
remainder of Europe, Australia and New Zealand and North
America were compared in the earlier BTS guidelines. 1 Other
European studies confirm previous knowledge. 30 31 48 [Ib] [Ib] [II] For
patients managed in the community and in hospital, the
frequency of pathogens is broadly similar to that in the UK. [II]
This suggests that aspects of these guidelines will be applicable
to other countries as well as the UK. The absence of studies
using sensitive methods for pneumococcal polysaccharide
capsular antigen detection for the identification of S pneumoniae
may be the explanation for the lower frequency outside the UK.
The apparent differences in M pneumoniae may relate to the
presence or absence of epidemics at the time of the study.
Chlamydophila pneumoniae is identified frequently in some
European countries, but recent studies in Germany 31 [Ib] and
the Netherlands 31 [II] found frequencies of only 0.9% and 3%,
respectively.
Antibiotic-resistant S pneumoniae appears to be no more
frequent in severely ill patients admitted to the ICU than in
those managed on an ordinary hospital ward in a country where
such resistance is common. 49 [Ib] Studies of patients with severe
CAP from Europe suggest a lower frequency of legionella and a
higher frequency of Gram-negative enteric bacilli infections
compared with the UK. These may be real or methodological.
[IVa]
A frequency of 8% for non-pneumophila legionella species
was found in one Dutch study. 32 [II] A study of hospitalised
patients in Spain 50 [Ib] found a frequency of mixed aetiology of
13%, similar to the average figure of 11% for the UK. Another
Spanish study found a frequency of 5.7%. 51 [Ib] A recent
publication showed a high frequency of C burnetii infection in
52 [Ib]
the Canary Islands.
3.4 How does the aetiology differ in certain geographical areas?
Specific studies suggest a higher frequency of certain pathogens
in some geographical areas as described in the 2001 BTS
guidelines (table 3). 1 A global study found a frequency of
atypical pathogens of 20–28% of cases in different regions of the
Thorax 2009;64(Suppl III):iii1–iii55. doi:10.1136/thx.2009.121434