Significance of the progression of respiratory symptoms for predicting community-acquired pneumonia in general practice.

Background and objective:  Early diagnosis improves outcomes in patients with community-acquired pneumonia (CAP). However, prediction of CAP based on symptoms and signs is difficult. The present study investigated the evaluation of progression of symptoms as a factor for predicting the occurrence of CAP in general practice. Methods:  Consecutive patients (n = 406) suspected of having CAP on routine clinical examination were studied retrospectively. Selection of patients with suspected CAP was based on progression of symptoms after 5 days, as well as published criteria. Diagnostic yields for the recommended criteria and our proposed criteria were then compared. Scoring systems for the prediction of CAP were designed, based on the results of multiple regression analysis. The diagnostic performance of these systems, including or excluding symptom progression, was compared using the areas under receiver operating characteristic curves. Results:  The sensitivity and specificity of the recommended criteria and our proposed criteria were 0.75 and 0.44, and 0.93 and 0.38, respectively. Sputum production, dyspnoea, fever > 38°C, heart rate > 100 beats/min, decreased breath sounds, coarse crackles and progression of symptoms significantly increased the likelihood of CAP. Areas under receiver operating characteristic curves analysis showed that the diagnostic prediction of CAP was significantly improved when the scoring system included progression of symptoms. Conclusions:  Progression of symptoms was a significant factor for predicting CAP and selecting patients who required CXR. Inclusion of progression of symptoms among the other recommended criteria, namely, dyspnoea, fever > 38°C, heart rate > 100 beats/min and abnormal chest findings, improved prediction of the incidence of CAP in general practice.