Analytical performance evaluation of the new GEM® Premier™ 5000 analyzer in comparison to the GEM® Premier™ 4000 and the RapidPoint® 405 systems.

AIM OF THE STUDY: Blood gas analysis (BGA) is essential for the diagnosis and management of acid-base imbalances. We evaluated and compared the analytical characteristics of the new GEM® Premier™ 5000 (GP5000) (Instrumentation Laboratory, Bedford, MA, United States) BGA point-of-care (POC) device with those of the GEM® Premier™ 4000 (GP4000) (Instrumentation Laboratory, Bedford, MA, United States) and RapidPoint® 405 (RP405) (Siemens Healthcare, Milan, Italy) POC analyzers. The effect of sample mixing on patient results was also studied. MATERIAL AND METHODS: Quantitative measurement of pH, pCO2, pO2, Na+, K+, Cl-, iCa2+, glucose, lactate, tHb, COHb, MetHb, O2Hb, HHb and Hct were carried out. The imprecision study (IS) and method comparison study (MS) were performed according to CLSI EP guidelines, using respectively internal as well as external quality controls (IS) and whole blood samples collected from the routine analysis (MS). RESULTS: GP5000 demonstrated satisfactory characteristics in the IS showing comparable (GM4000) or even better (RP405) imprecision results than the routine POC devices. Good performance was observed in the MS both using GP4000 and RP405 as reference instruments. Pre-analytical sample management can heavily affect the accuracy of BGA results. In the specimen mixing evaluation, a significant improvement in results accuracy was observed when mixing procedures were more meticulous. CONCLUSIONS: Considering the overall analytical performance observed, the ease of use of the system, the rapid time-to-results and the innovative Intelligent Quality Management technology (iQM2®), GP5000 seems suitable to be used in clinical care for safe patient management. Additionally, effective sample mixing upon draw and before analysis is strongly advisable in order to ensure the most clinically reliable BGA results.

Multidimensional Prognostic Index and pro-adrenomedullin plasma levels as mortality risk predictors in older patients hospitalized with community-acquired pneumonia: a prospective study.

BACKGROUND: To evaluate the prognostic accuracy of proadrenomedullin (proADM) in comparison with and in addition to the Multidimensional Prognostic Index (MPI), a validated predictive tool for mortality derived from a comprehensive geriatric assessment (CGA) to predict one-month mortality risk in older patients hospitalized with community-acquired pneumonia (CAP). METHODS: All patients aged 65 years and older, consecutively admitted to an acute geriatric ward with a diagnosis of CAP from February to July 2012. At admission and at discharge they were submitted to a standard CGA in order to calculate MPI. Moreover, plasma samples were taken at baseline and after one, three and five days of hospitalization for the analysis of pro-ADM. RESULTS: Fifty patients (mean age 86.2±7.5 years), with 31 at high risk of mortality (MPI-3) were enrolled. ProADM and MPI, both at admission and at discharge, were significant predictor of mortality. As expected, MPI at admission showed lower predictive accuracy than MPI at discharge (survival C-statistic 0.667 vs. 0.851). The addition of proADM to the MPI at admission significantly increased accuracy in predicting one-month mortality (C-statistics from 0.667 to 0.731, P=0.018 at baseline; from 0.667 to 0.733, P=0.008 at 1 day; from 0.633 to 0.724; P=0.019 at 3 days; from 0.667 to 0.828; P=0.003 at 5 days). Conversely, adding pro-ADM to the MPI at discharge did not significantly improve the model's prognostic accuracy. CONCLUSIONS: ProADM may significantly improve the prognostic accuracy of the MPI at admission in hospitalized elderly patients with CAP.

Clinical performance of cardiac Troponin I: A comparison between the POCT AQT90 FLEX and the Dimension Vista analyzer in an emergency setting.

BACKGROUND: Cardiac troponin [cTn (I or T)] is the preferred biomarker for the diagnosis of myocardial infarction (MI). AIM: We studied the analytical performance of the POCT AQT90 FLEX cTnI assay and its diagnostic accuracy, in comparison to the Dimension Vista cTnI method, in patients presenting to the Emergency Department (ED) with suspect of acute coronary syndrome (ACS). METHODS: 786 consecutive patients were enrolled. cTnI was measured at admission to the ED and about 3 and 6 hours later. The imprecision study was carried out using different lots of quality controls (QCs). ROC curve analysis was conducted using discharge diagnoses in order to verify the global diagnostic accuracy. RESULTS: The concentrations measured in the QCs ranging from 0.033 to 1.26µg/L show CVs% ranging from 2.81 to 7.56%, comparable to those declared by the manufacturer. Passing-Bablok and linear regression analysis show a high significant correlation (R2=0.90, p<0.0001); Bland-Altman test describes a statistically significant negative bias (Bias=-0.2336; 95%CI=-0.4217/-0.0456, p=0.0150). ROC curves obtained using Dimension Vista and AQT90 FLEX cTnI assays displayed similar clinical performance being not statistically significant the difference of the corresponding AUC. Comparing sensitivity and specificity of cTnI concentrations obtained from the ROC curve analysis using AQT90 FLEX, we found a "best cut-off" (0.014µg/L) lower than that declared from the manufacturer (0.023µg/L). CONCLUSIONS: The comparison of two different assays of cTnI against a diagnosis of acute MI (AMI) shows that both assays behave equally well with a high degree of sensitivity and specificity. The resulting "best cut-off" suggests that this AQT90 FLEX cTnI concentration could be evaluated as the potentially new "clinically usable" cut-off for AMI/myocardial necrosis diagnoses.