Midregional Proadrenomedullin as a Prognostic Tool in Community-Acquired Pneumonia

Background: Midregional proadrenomedullin (MR-proADM) is a potential prognostic biomarker in patients with community-acquired pneumonia (CAP). Previous work has been hampered by, sample size and illness spectrum limits. We sought to describe the pattern of MR-proADM in a broad CAP cohort, confirm its prognostic role, and compare its performance to procalcitonin, a novel biomarker of infection. Methods: We conducted a multicenter prospective cohort study, in 28 community, and teaching EDs. Patients with a clinical and radiographic diagnosis of CAP were enrolled. We stratified MR-proADM levels a priori into quartiles and quantified severity of illness using the pneumonia severity, index (PSI); and confusion (abbreviated mental test score of <= 8), urea >= 7 mmol/L, respiratory, rate >= 30 breaths/min, BP < 90 mm Hg systolic or < 60 mm Hg diastolic, age >= 65 mars (CURB-65). The primary outcome was 30-day mortality. Results: A total of 1,65:3 patients formed the study cohort. MR-proADM levels consistently, rose with PSI class and 30-day mortality (p < 0.001). MR-proADM had a higher area under the curve for 30-day mortality than procalcitonin (0.76 vs 0.65, respectively; p < 0.001), but adding NIR-proADM to the PSI in all subjects minimally improved performance. Among low-risk subjects (PSI classes I to III), mortality was low and did not differ by MR-proADM quartile. However, among high-risk subjects (PSI class IV/V; n = 546), subjects in the highest MR-proADM quartile (n = 232; 42%) had higher 30-day mortality than those in MR-proADM quartiles 1 to 3 (23% vs 9%, respectively; p < 0.0001). Similar results were seen with CURB-65. MR-proADM and procalcitonin levels were generally, concordant; only 6% of PSI class IV/V subjects in the highest MR-proADM quartile had very, low procalcitonin levels (< 0.1 ng/mL). Conclusions: In our multicenter CAP cohort, MR-proADM levels correlate with increasing severity of illness and death. High MR-proADM levels offer additional risk stratification in high-risk CAP patients, but otherwise MR-proADM levels do not alter PSI-based risk assessment in most CAP patients. (CHEST 2009; 136:823-831)