• Pneumonia

We thank Challen et al for their interest in the guidelines and for raising an important discussion point. In describing disease severity, mortality is the main outcome measure used in the majority of studies of community acquired pneumonia (CAP). The largest evidence base therefore relates to this very specific outcome. In contrast, criteria for admission to critical care units vary across units and from country to country and, in practice, only a proportion of patients with CAP are usually considered suitable for admission.

As Challen et al suggest, no prognostic model is perfect. The CURB65 score is comparable to more complicated models such as the Pneumonia Severity Index that takes into account 20 different variables. Studies of the CURB65 score …