Pneumonia in adults: diagnosis and management

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 X‑ray showing new shadowing that is not due to any other cause (such as pulmonary oedema or infarction). In this guideline pneumonia is classified as community‑acquired or hospital‑acquired, 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 community‑acquired pneumonia. It is diagnosed in 5–12% of adults who present to GPs with symptoms of lower respiratory tract infection, and 22–42% 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 community‑acquired pneumonia are managed in an intensive care unit, and for these people the risk of dying is more than 30%. More than half of pneumonia‑related deaths occur in people older than 84 years.

At any time 1.5% of hospital inpatients in England have a hospital‑acquired respiratory infection, more than half of which are hospital‑acquired pneumonia and are not associated with intubation. Hospital‑acquired pneumonia is estimated to increase hospital stay by about 8 days and has a reported mortality rate that ranges from 30–70%. 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 evidence‑based guidance on the management of hospital‑acquired 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 community‑acquired pneumonia in adults. However, it does not provide recommendations on areas of care where best practice is already established, such as diagnosis using chest X‑ray. It does not cover bronchiectasis complicated by pneumonia, or people 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 end‑of‑life care. For guidance on antibiotic treatment of pneumonia, see NICE's guidelines on pneumonia (community-acquired): antimicrobial prescribing and pneumonia (hospital-acquired): antimicrobial prescribing.