A PROSPECTIVE-STUDY OF DAILY MEASUREMENT OF C-REACTIVE PROTEIN IN SERUM OF ADULTS WITH NEUTROPENIA

A total of 1,622 daily measurements of the level of C-reactive protein (CRP) in the serum of 40 hospitalized patients with neutropenia were made during 55 study periods from October 1990 through February 1993 ( mean, 29.5 measurements per period). Clinical events were categorized into four groups: group I (bloodstream infection), group II (significa nt bacterial or fungal infection without bloodstream infection), group III (fever without an obvious source), and group IV (drug-related fev er). There was a strong association between baseline elevation of the CRP level (greater than or equal to 100 mg/L) and tumor-associated fev er (P = .0005); the resolution of such fever coincided with a decrease in the CRP level following chemotherapy. Levels of CRP increased by g reater than or equal to 40 mg/L in 10 (31%) of 32 cases during the 48- 72 hours preceding the clinical diagnosis of a subsequently demonstrab le infection-often pneumonia without bloodstream infection. CRP values on day 2 (1 day after the diagnosis of a clinical event) were signifi cantly higher for events in groups I and II than for those in group II I (P < .01) but not those in group IV. With regard to significant infe ctions, a day-2 CRP value of greater than or equal to 40 mg/L was 100% sensitive and an increase in CRP level of greater than or equal to 50 mg/L from day 1 to day 2 had a positive predictive value of 95%. We c onclude that serial measurements of serum CRP levels may be helpful in determining the extent of evaluation required for a newly febrile neu tropenic patient and possibly in accelerating the detection of an othe rwise unsuspected infection.