Importance of severity assessment: community-acquired pneumonia.

Pneumonia Severity Index and CURB 65 are the two most important prognostic scoring tools to predict mortality for patients with CAP. These tools accurately predict mortality but do not directly measure disease severity. The clinical assessment is still required to decide hospital admission or ICU care. Prognostic scoring systems have been used to assist in the site-of-care decisions, with limited success. PSI and CURB 65 are complementary to one another, as they identify different segments of the CAP population. The PSI developed to predict low-risk patients is complex to use. Also, its role in identifying critically ill individuals is limited because it may overestimate the mortality risk in old patients with comorbidity and may underestimate the need for ICU care in younger patients who have not been previously ill. The CURB 65 is simple and is particularly useful for clinicians in identifying vital sign abnormalities that defne severe illness. However, it is unable to detect patients with multiple comorbid illnesses effectively, particularly in the presence of decompensated illnesses associated with CAP. At best, these scoring systems are decision-support tools, and cannot be used as 'rules' for site-of-care decisions. In future, biomarkers such as PCT are likely to be used to predict CAP mortality and to guide management decisions. Preliminary data indicate that measurement of PCT may be valuable and that the findings may complement the risk stratifcation results from prognostic scoring models.