C-reactive protein for discriminating treatment failure from slow responding pneumonia

The management of patients with community-acquired pneumonia (CAP) who fail to improve constitutes a challenge for clinicians. This study investigated the usefulness of C-reactive protein (CRP) changes in discriminating true treatment failure from slow response to treatment.

This prospective multicenter observational study investigated the behavior of plasma CRP levels on days 1 and 4 in hospitalized patients with CAP. We identified non-responding patients as those who had not reached clinical stability by day 4. Among them, true treatment failure and slow response situations were defined when initial therapy had to be changed or not after day 4 by attending clinicians, respectively.

By day 4, 78 (27.4%) out of 285 patients had not reached clinical stability. Among them, 56 (71.8%) patients were cured without changes in initial therapy (mortality 0.0%), and in 22 (28.2%) patients, the initial empirical therapy needed to be changed (mortality 40.9%). By day 4, CRP levels fell in 52 (92.9%) slow responding and only in 7 (31.8%) late treatment failure patients (p<0.001). A model developed including CRP behavior and respiratory rate at day 4 identified treatment failure patients with an area under the Receiver Operating Characteristic curve of 0.87 (CI 95%, 0.78-0.96).

Changes in CRP levels are useful to discriminate between true treatment failure and slow response to treatment and can help clinicians in management decisions when CAP patients fail to improve.