Influence of age on the clinical differentiation of atypical pneumonia in adults.

BACKGROUND AND OBJECTIVE

The Japanese Respiratory Society (JRS) scoring system is a useful tool for the early and simple presumptive diagnosis of atypical pneumonia (Mycoplasma pneumoniae and Chlamydia pneumoniae pneumonia). However, it has been suggested that it is difficult to diagnose atypical pneumonia in the elderly using this system. In the present study, we evaluated the accuracy and usefulness of the JRS scoring system for diagnosing atypical pneumonia in different age groups.

METHODS

Cases of M. pneumoniae (n = 262), C. pneumoniae (n = 98) and common bacterial pneumonia (n = 364) were analysed.

RESULTS

For both atypical pneumonias, the frequency of comorbid illnesses and being in a higher risk category were significantly greater in elderly (age ≥60 years) than in non-elderly patients (age <60 years). One or more additional aetiological factors were more frequently present in elderly than in non-elderly patients. The diagnostic sensitivity and specificity for atypical pneumonia were 39% and 88%, respectively, in the elderly group, and 86% and 88%, respectively, in the non-elderly group. When the patients were stratified into 10-year age groups, the diagnostic sensitivity was highest in the 18- to 29-year age group and decreased from the youngest to the oldest age group.

CONCLUSIONS

These results indicate that it is difficult to distinguish between atypical pneumonia and bacterial pneumonia in the elderly using the JRS scoring system. When treating patients aged ≥60 years, physicians should use fluoroquinolones or β-lactam antibiotics + macrolides as empirical first-choice drugs so as to always provide antibiotic protection against potential atypical pathogens.