Patients with acute cough that have pneumonia can be identified using a diagnostic score based on signs, symptoms, and serum C reactive protein levels, say researchers
The GRACE study looked at 2,820 patients with acute cough from primary care settings across 12 European countries, of which 140 were diagnosed with pneumonia. Study participants had their history taken, a physical examination and their CRP and procalcitonin levels measured on the day of presentation and a chest x-ray within seven days of presentation. Later, patients were re-assessed with 1,571 having a diagnosis of absence or presence of pneumonia.
The clinical predictive items were absence of a runny nose, presence of breathlessness, crackles and diminishes breath sounds on auscultation, tachycardia and fever. The addition of serum CRP at the optimal cut-off of>30 mg/L improved the diagnostic classification (net classification improvement of 28%).
Based on symptoms, signs and CRP>30 mg/L, the risk of pneumonia was low (<2.5%) in patients with a prevalence of 2% while the prevalence of pneumonia was 31% in the 132 patients which were classified as high risk (>20%). The use of a diagnostic tool including symptoms, signs and CRP>30 mg/L identified proportions of pneumonia of 0.7%, 3.8% and 18.2% in the low, intermediate and high risk group respectively. Procalcitonin levels were not relevant to the results.
What do the results mean for GPs?
The authors comment: ‘This is the first study to quantify the independent diagnostic value of symptoms, signs, and additional diagnostic value of inflammatory markers for pneumonia in patients presenting with acute cough in primary care that included an adequate number of cases of pneumonia.’ They concluded: ‘A clinical rule based on symptoms and signs to predict pneumonia in patients presenting to primary care with acute cough performed best in patients with mild or severe clinical presentation. Addition of CRP concentration at the optimal cut off of >30 mg/L improved diagnostic information, but measurement of procalcitonin concentration did not add clinically relevant information in this group.