Pneumonia in adults: diagnosis and management

This guideline was developed before the COVID-19 pandemic. It covers diagnosing and managing pneumonia in adults who do not have COVID-19. It aims to improve accurate assessment and diagnosis of pneumonia to help guide antibiotic prescribing and ensure that people receive the right treatment.

# Introduction
Pneumonia is an infection of the lung tissue. When a person has pneumonia the air sacs in their lungs become filled with microorganisms, fluid and inflammatory cells and their lungs are not able to work properly. Diagnosis of pneumonia is based on symptoms and signs of an acute lower respiratory tract infection, and can be confirmed by a chest Xray showing new shadowing that is not due to any other cause (such as pulmonary oedema or infarction). In this guideline pneumonia is classified as communityacquired or hospitalacquired, based on different microbial causes and patient factors, which need different management strategies.
Every year between 0.5% and 1% of adults in the UK will have communityacquired pneumonia. It is diagnosed in 512% of adults who present to GPs with symptoms of lower respiratory tract infection, and 2242% of these are admitted to hospital, where the mortality rate is between 5% and 14%. Between 1.2% and 10% of adults admitted to hospital with communityacquired pneumonia are managed in an intensive care unit, and for these patients the risk of dying is more than 30%. More than half of pneumoniarelated deaths occur in people older than 84 years.
At any time 1.5% of hospital inpatients in England have a hospitalacquired respiratory infection, more than half of which are hospitalacquired pneumonia and are not associated with intubation. Hospitalacquired pneumonia is estimated to increase hospital stay by about 8 days and has a reported mortality rate that ranges from 3070%. Variations in clinical management and outcome occur across the UK.
The guideline is needed because pneumonia is common and has a high mortality rate. The  British Thoracic Society (2009) has published guidance on the management of community-acquired pneumonia in adults, but there is a lack of evidencebased guidance on the management of hospitalacquired pneumonia. For both types of pneumonia there is variation in care and areas of uncertainty for best practice, and these are the main focus of this guideline.
This guideline provides recommendations for the diagnosis of pneumonia, and aspects of management of communityacquired pneumonia in adults. However, it does not provide recommendations on areas of care where best practice is already established, such as diagnosis using chest Xray. It does not cover bronchiectasis complicated by pneumonia, or patients who acquire pneumonia while intubated or in an intensive care unit, who are immunocompromised, or in whom management of pneumonia is an expected part of endoflife care. For guidance on antibiotic treatment of pneumonia, see NICE's guidelines on pneumonia (community-acquired): antimicrobial prescribing and pneumonia (hospital-acquired): antimicrobial prescribing.# Recommendations
The following guidance is based on the best available evidence. The full guideline gives details of the methods and the evidence used to develop the guidance.
People have the right to be involved in discussions and make informed decisions about their care, as described in NICE's information on making decisions about your care.
Making decisions using NICE guidelines explains how we use words to show the strength (or certainty) of our recommendations, and has information about prescribing medicines (including off-label use), professional guidelines, standards and laws (including on consent and mental capacity), and safeguarding.

# Terms used in this guideline

## Clinical diagnosis of community-acquired pneumonia
Diagnosis based on symptoms and signs of lower respiratory tract infection in a patient who, in the opinion of the GP and in the absence of a chest Xray, is likely to have communityacquired pneumonia. This might be because of the presence of focal chest signs, illness severity or other features.

## Community-acquired pneumonia
Pneumonia that is acquired outside hospital. Pneumonia that develops in a nursing home resident is included in this definition. When managed in hospital the diagnosis is usually confirmed by chest Xray.

## Hospital-acquired pneumonia
Pneumonia that develops 48 hours or more after hospital admission and that was not incubating at hospital admission. When managed in hospital the diagnosis is usually confirmed by chest Xray. For the purpose of this guideline, pneumonia that develops in hospital after intubation (ventilatorassociated pneumonia) is excluded from this definition.

## Lower respiratory tract infection
An acute illness (present for 21 days or less), usually with cough as the main symptom, and with at least 1 other lower respiratory tract symptom (such as fever, sputum production, breathlessness, wheeze or chest discomfort or pain) and no alternative explanation (such as sinusitis or asthma). Pneumonia, acute bronchitis and exacerbation of chronic obstructive airways disease are included in this definition.

## Mortality risk
The percentage likelihood of death occurring in a patient in the next 30 days.

## Severity assessment
A judgement by the managing clinician as to the likelihood of adverse outcomes in a patient. This is based on a combination of clinical understanding and knowledge in addition to a mortality risk score. The difference between categories of severity and mortality risk can be important. Typically the mortality risk score will match the severity assessment. However, there may be situations where the mortality score does not accurately predict mortality risk and clinical judgement is needed. An example might be a patient with a low mortality risk score who has an unusually low oxygen level, who would be considered to have a severe illness.

# Presentation with lower respiratory tract infection
For people presenting with symptoms of lower respiratory tract infection in primary care, consider a point of care Creactive protein test if after clinical assessment a diagnosis of pneumonia has not been made and it is not clear whether antibiotics should be prescribed. Use the results of the Creactive protein test to guide antibiotic prescribing in people without a clinical diagnosis of pneumonia as follows:
Do not routinely offer antibiotic therapy if the Creactive protein concentration is less than 20 mg/litre.
Consider a delayed antibiotic prescription (a prescription for use at a later date if symptoms worsen) if the Creactive protein concentration is between 20 mg/litre and 100 mg/litre.
Offer antibiotic therapy if the Creactive protein concentration is greater than 100 mg/litre.

# Community-acquired pneumonia

## Severity assessment in primary care
When a clinical diagnosis of community-acquired pneumonia is made in primary care, determine whether patients are at low, intermediate or high risk of death using the CRB65 score (see box 1).
Box 1 CRB65 score for mortality risk assessment in primary care
CRB65 score is calculated by giving 1 point for each of the following prognostic features:
confusion (abbreviated Mental Test score 8 or less, or new disorientation in person, place or time). For guidance on delirium, see the NICE guideline on delirium.
raised respiratory rate (30 breaths per minute or more)
low blood pressure (diastolic 60 mmHg or less, or systolic less than 90 mmHg)
age 65 years or more.
Lim WS, van der Eerden MM, Laing R, et al. (2003) Defining communityacquired pneumonia severity on presentation to hospital: an international derivation and validation study. Thorax 58: 37782
Patients are stratified for risk of death as follows:
: low risk (less than 1% mortality risk)
-r 2: intermediate risk (110% mortality risk)
-r 4: high risk (more than 10% mortality risk).
Use clinical judgement in conjunction with the CRB65 score to inform decisions about whether patients need hospital assessment as follows:
consider homebased care for patients with a CRB65 score of 0
consider hospital assessment for all other patients, particularly those with a CRB65 score of 2 or more.

## Severity assessment in hospital
When a diagnosis of community-acquired pneumonia is made at presentation to hospital, determine whether patients are at low, intermediate or high risk of death using the CURB65 score (see box 2).
Box 2 CURB65 score for mortality risk assessment in hospital
CURB65 score is calculated by giving 1 point for each of the following prognostic features:
confusion (abbreviated Mental Test score 8 or less, or new disorientation in person, place or time). For guidance on delirium, see the NICE guideline on delirium
raised blood urea nitrogen (over 7 mmol/litre)
raised respiratory rate (30 breaths per minute or more)
low blood pressure (diastolic 60 mmHg or less, or systolic less than 90 mmHg)
age 65 years or more.
Patients are stratified for risk of death as follows:
-r 1: low risk (less than 3% mortality risk)
: intermediate risk (315% mortality risk)
to 5: high risk (more than 15% mortality risk).
Lim WS, van der Eerden MM, Laing R, et al. (2003) Defining communityacquired pneumonia severity on presentation to hospital: an international derivation and validation study. Thorax 58: 37782
Use clinical judgement in conjunction with the CURB65 score to guide the management of communityacquired pneumonia, as follows:
consider homebased care for patients with a CURB65 score of 0 or 1
consider hospitalbased care for patients with a CURB65 score of 2 or more
consider intensive care assessment for patients with a CURB65 score of 3 or more.
Stratify patients presenting with communityacquired pneumonia into those with low, moderate or highseverity disease. The grade of severity will usually correspond to the risk of death.

## Microbiological tests
Do not routinely offer microbiological tests to patients with lowseverity communityacquired pneumonia.
For patients with moderate or highseverity communityacquired pneumonia:
take blood and sputum cultures and
consider pneumococcal and legionella urinary antigen tests.

## Timely diagnosis and treatment
Put in place processes to allow diagnosis (including Xrays) and treatment of communityacquired pneumonia within 4 hours of presentation to hospital.

## Antibiotic therapy
See the NICE guideline on pneumonia (community-acquired): antimicrobial prescribing for recommendations on antibiotic therapy.
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## Glucocorticoid treatment
Do not routinely offer a glucocorticoid to patients with communityacquired pneumonia unless they have other conditions for which glucocorticoid treatment is indicated.

## Monitoring in hospital
Consider measuring a baseline Creactive protein concentration in patients with communityacquired pneumonia on admission to hospital, and repeat the test if clinical progress is uncertain after 48 to 72 hours.

## Safe discharge from hospital
Do not routinely discharge patients with communityacquired pneumonia if in the past 24 hours they have had 2 or more of the following findings:
temperature higher than 37.5C
respiratory rate 24 breaths per minute or more
heart rate over 100 beats per minute
systolic blood pressure 90 mmHg or less
-xygen saturation under 90% on room air
abnormal mental status
inability to eat without assistance.
Consider delaying discharge for patients with communityacquired pneumonia if their temperature is higher than 37.5C.

## Patient information
Explain to patients with communityacquired pneumonia that after starting treatment their symptoms should steadily improve, although the rate of improvement will vary with the severity of the pneumonia, and most people can expect that by:
week: fever should have resolved
weeks: chest pain and sputum production should have substantially reduced
weeks: cough and breathlessness should have substantially reduced
months: most symptoms should have resolved but fatigue may still be present
months: most people will feel back to normal.
Advise patients with communityacquired pneumonia to consult their healthcare professional if they feel that their condition is deteriorating or not improving as expected.

# Hospital-acquired pneumonia

## Antibiotic therapy
See the NICE guideline on pneumonia (hospital-acquired): antimicrobial prescribing for recommendations on antibiotic therapy for hospital-acquired pneumonia.
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Deleted.# Research recommendations
The Guideline Development Group has made the following recommendations for research, based on its review of evidence, to improve NICE guidance and patient care in the future.

# Urine antigen testing
In moderate to highseverity communityacquired pneumonia does using legionella and pneumococcal urinary antigen testing in addition to other routine tests improve outcomes?

## Why this is important
Current practice and evidence suggest that giving a combination of antibiotics to patients with moderate to highseverity communityacquired pneumonia reduces mortality. However, no randomised controlled trial has looked at using urinary antigen testing to target treatment. If effective, such targeted treatment could improve antibiotic stewardship, increase compliance and potentially reduce costs.

# C-reactive protein-guided antibiotic duration
In patients hospitalised with moderate to highseverity communityacquired pneumonia, does using Creactive protein monitoring in addition to clinical observation to guide antibiotic duration safely reduce the total duration of antibiotic therapy compared with a fixed empirical antibiotic course?

## Why this is important
The recommended duration of antibiotic therapy for adults hospitalised with moderate to highseverity communityacquired pneumonia is based on evidence of very low quality; no relevant clinical trials were identified by NICE. The burden of communityacquired pneumonia is large, and its treatment accounts for a high proportion of antibiotic use in hospitals. Overuse of antibiotics is associated with antimicrobial resistance, which is a national and global priority.

# Continuous positive pressure ventilation
What is the clinical effectiveness of continuous positive pressure ventilation compared with usual care in patients with communityacquired pneumonia and type I respiratory failure without a history of chronic obstructive pulmonary disease?

## Why this is important
Type I respiratory failure is a common feature of pneumonia. Mild type I respiratory failure is easily corrected with low levels of supplemental oxygen, whereas severe lifethreatening hypoxemia needs immediate intubation and invasive ventilation. Research into whether continuous positive pressure ventilation improves gas exchange and subsequent outcomes, such as mortality, could help improve care for patients with respiratory failure between these extremes.

# Hospital-acquired pneumonia
Can rapid microbiological diagnosis of hospitalacquired pneumonia reduce the use of extended-spectrum antibiotic therapy, without adversely affecting outcomes?

## Why this is important
Data are limited on the microbiology of hospitalacquired pneumonia to guide antibiotic therapy. Hospitalacquired infections can be caused by highly resistant pathogens that need treatment with extendedspectrum antibiotics (for example, extendedspectrum penicillins, thirdgeneration cephalosporins, aminoglycosides, carbapenems, linezolid, vancomycin, or teicoplanin), as recommended by British Society of Antimicrobial Chemotherapy guidance. Because routine microbial tests lack sensitivity and take 2448 hours to identify a causative pathogen, patient characteristics are used to guide antibiotic choice. However, this may lead to unnecessary use of extendedspectrum antibiotics in patients infected with nonresistant organisms, and inappropriate use of firstline antibiotics (such as betalactam stable penicillins, macrolides or doxycycline) in patients infected with resistant organisms.
Rapid diagnostic tests to identify causative bacterial pathogens and determine whether they are resistant to antibiotics may have a role in guiding antibiotic choice for postoperative hospitalacquired pneumonia.
To limit population variability and include highrisk patients spending time in intensive care, studies should include postoperative patients from different surgical specialties.