History and exam

Key diagnostic factors

common

cough with increasing sputum production

Symptoms of a lower respiratory tract infection such as cough are frequently seen in people with community-acquired pneumonia (CAP).[74]​​[77]

  • Cough is one of the most common symptoms of CAP.[74] It is usually productive. 

  • Mucopurulent sputum suggests a bacterial cause. Scant or watery sputum may indicate infection with an atypical pathogen.[74]

  • Older adults may not present with cough and are more likely to have non-specific symptoms (e.g., confusion); they may also be afebrile.[74]

dyspnoea

Dyspnoea is frequently seen in people with community-acquired pneumonia (CAP).[74][85]​ [77]

  • Dyspnoea is one of the most useful predictive symptoms of CAP in the community setting (together with fever, tachypnoea, pleuritic chest pain, and new/localising signs on chest examination).[74]

pleuritic chest pain

Pleuritic chest pain is frequently reported in people with community-acquired pneumonia (CAP), occurring in 30% of patients.[74]​​[77][129]

  • Pleuritic chest pain is one of the most useful predictive symptoms of CAP in the community setting (together with fever, dyspnoea/tachypnoea, and new/localising signs on chest examination).[74]

rigors or night sweats

Rigors or night sweats are commonly reported in people with community-acquired pneumonia, but are less frequent in older adults.[74][85]

fever

Fever is commonly seen in people with community-acquired pneumonia (CAP), although older people may be afebrile.[74]​​[77]

  • Fever (>38ºC [>100ºF]) is one of the most useful predictive symptoms of CAP in the community setting (together with dyspnoea/tachypnoea, pleuritic chest pain, and new/localising signs on chest examination).[74]

abnormal respiratory examination findings

New focal chest signs are frequently identified in people with community-acquired pneumonia (CAP).[74]​​​[77]​Common findings include crackles, reduced breath sounds, dullness to percussion, and wheeze.

Tachypnoea is one of the most useful predictive symptoms of CAP in the community (together with fever, dyspnoea, pleuritic chest pain, and new/localising signs on chest examination.[74]​​​

confusion

Confusion is frequently seen in older adults presenting with community-acquired pneumonia (CAP).[74][85][77]

  • Older adults often present with non-specific symptoms such as confusion or deterioration of underlying diseases, sometimes without fever or focal chest findings.[74]​​[91][77]

  • Confusion may also be a prominent feature of atypical CAP, for example Legionella pneumophila pneumonia, where it can occur alongside other systemic symptoms such as diarrhoea.[130]

presence of risk factors

Take a structured history to identify risk factors for community-acquired pneumonia (CAP), to help distinguish it from alternative diagnoses and to determine factors that may influence management.[74]​​[77]

(*denotes a strong risk factor for CAP)

  • Age ≥65 years*

    • Incidence and mortality from CAP increase significantly with age.​[2][3][97]

  • Male sex

    • CAP tends to be more severe in males, with higher overall and age-specific mortality compared with females.[64]

  • Residence in a nursing home*

    • Mortality rates due to pneumonia in nursing home residents have been reported to reach 55%.[98][99] 

    • Nursing home residents also have an increased risk of aspiration pneumonia.[100]

  • Regular contact with children*

    • Regular contact with children is associated with an increased risk of CAP, likely due to greater exposure to respiratory pathogens.[60]

  • Chronic respiratory disease

    • COPD*, asthma, and bronchitis are associated with a two- to fourfold increased risk of CAP.[1] 

    • COPD is an independent risk factor for mortality in patients with CAP.[46]

  • Other chronic comorbidities

    • Chronic heart disease: associated with a 60% to 70% increase in CAP risk.[1] Heart failure in particular appears to confer a higher risk, with adjusted estimates suggesting up to a two- to threefold increase in CAP incidence.[1]​​ 

    • Diabetes: associated with a moderate increase in the risk of CAP and an increased risk of pneumonia-related hospitalisation.[1][65]​ The risk of severe pneumococcal bacteraemia is higher in people with diabetes.[67]

    • Chronic kidney disease: increases the risk of developing CAP approximately twofold and is a significant risk factor for mortality in patients with CAP.[1][68][69]

    • Chronic liver disease: increases the risk of developing CAP approximately twofold and has been identified as a risk factor for pulmonary complications in patients hospitalised with pneumococcal pneumonia.[1][71]

    • HIV infection*: people with HIV infection are at increased risk of developing bacterial CAP. Although the introduction of antiretroviral therapy has improved immune function and reduced the incidence of CAP, it continues to be a major cause of morbidity and mortality in this population. This ongoing risk is attributed to persistent immune dysfunction and chronic immune activation, despite viral suppression. Reported mortality rates for HIV-infected patients with CAP range from 6% to 15%.[63]

  • Alcohol use/misuse*

    • People who consume alcohol, particularly at higher levels, have an 83% higher risk of developing CAP than non-drinkers or light drinkers (relative risk 1.83).[53] 

    • For every 10-20 g higher alcohol intake per day, there is an 8% increase in the risk of CAP.[53]

  • Smoking*

    • Both current and former smokers are at greater risk of developing CAP than never-smokers.[51]

    • Passive smoking in the home also increases the risk of CAP, particularly in adults aged ≥65 years.[52][51]

  • Poor oral hygiene*

    • Poor oral hygiene may increase CAP risk via oropharyngeal bacterial colonisation.[55]

  • Proton pump inhibitors (PPIs)*

    • CAP is among the most common adverse effects associated with the use of PPIs.[57] This association is thought to result from reduced gastric acid secretion, which facilitates colonisation of the upper respiratory tract by pathogenic organisms.​

    • Outpatient use of PPIs has been linked to a 1.5-fold increased risk of CAP.[58]

  • H2 antagonists

    • Associated with an increased risk of CAP.[59]

  • Prescribed opioids

    • Immunosuppressive opioids, in particular, are associated with an increased risk of CAP.[72]

  • Inhaled corticosteroids (particularly at higher doses), antipsychotics (especially atypical antipsychotics and use in older adults), and certain antidiabetic drugs are associated with an increased risk of CAP.[72][73]

Other diagnostic factors

common

myalgia

Non-specific symptoms such as myalgia are often reported in people with community-acquired pneumonia.[74]

  • Older adults, in particular, frequently present with atypical features, alongside deterioration of underlying chronic conditions.[74]

malaise

Non-specific symptoms such as malaise are often reported in people with community-acquired pneumonia.[74]

  • Older adults, in particular, frequently present with atypical features, alongside deterioration of underlying chronic conditions.[74]

anorexia

Non-specific symptoms such as anorexia are often reported in people with community-acquired pneumonia.[74]

  • Older people, in particular, frequently present with atypical features, alongside deterioration of underlying chronic conditions.[74]

lethargy

Non-specific symptoms such as lethargy are often reported in people with community-acquired pneumonia.[74]

  • Older people, in particular, frequently present with atypical features, alongside deterioration of underlying chronic conditions.[74]

worsening of pre-existing conditions

  • Older people, in particular, frequently present with atypical features, alongside deterioration of underlying chronic conditions.[74]

uncommon

sore throat

Atypical presentations of community-acquired pneumonia may include sore throat, often without clear chest findings.

  • Mycoplasma pneumoniae pneumonia in young adults may present with sore throat, headache, nausea, abdominal pain, and diarrhoea.[130]

headache

Atypical presentations of community-acquired pneumonia may include headache, often without clear chest findings.

  • Mycoplasma pneumoniae pneumonia in young adults may present with sore throat, headache, nausea, abdominal pain, and diarrhoea.[130]

nausea

Atypical presentations of community-acquired pneumonia may include nausea, often without clear chest findings.

  • Mycoplasma pneumoniae pneumonia in young adults may present with sore throat, headache, nausea, abdominal pain, and diarrhoea.[130]

abdominal pain

Atypical presentations of community-acquired pneumonia may include abdominal pain, often without clear chest findings.

  • Mycoplasma pneumoniae pneumonia in young adults may present with sore throat, headache, nausea, abdominal pain, and diarrhoea.[130]

diarrhoea

Atypical presentations of community-acquired pneumonia may include diarrhoea, often without clear chest findings.

  • Mycoplasma pneumoniae pneumonia in young adults may present with sore throat, headache, nausea, abdominal pain, and diarrhoea.[130]

  • Legionella pneumonia may present with constitutional upset, diarrhoea, and confusion.[130]

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