Lack of concordance between a rapid bedside and conventional laboratory method of cardiac troponin testing: impact on risk stratification of patients suspected of acute coronary syndrome.

OBJECTIVES: This study was designed to test the usefulness of a bedside assay as compared to a laboratory method of troponin testing to predict adverse cardiac outcome of chest pain patients. METHODS: We studied 358 ER visits of patients suspected of a non ST-elevation acute coronary syndrome. cTnI (Immulite, DPC) on a lab analyser and cTnT (Cardiac Reader, Roche) at bedside were measured at baseline. The between-assay level of concordance, reporting turnaround times and clinical outcomes during 180 days of follow-up were assessed. Death and myocardial infarction were then evaluated according to troponin result, either concordant negative, discordant or concordant positive. RESULTS: Discordance occurred in 11.4% (41/358) of cases. The proportion of patients with a positive cTnI and negative cTnT result (8.9%) versus the reverse (2.5%) differed significantly (p<0.001). The median time gained using the rapid test was 72 min. The rate of death and/or MI was 25% (10/40) among patients with discordant results as compared to 7.5% (17/228) with a concordant negative result (p<0.001). All patients from the discordant group with an event had a positive cTnI result, while cTnT was negative. CONCLUSION: Patients with a discordant reading were at high risk of adverse cardiac outcome, which was only identified by the laboratory cTnI assay. Markedly, the use of the rapid assay saved time at the expense of clinical sensitivity.

Serum creatine kinase as predictor of clinical course in rhabdomyolysis: a 5-year intensive care survey.

OBJECTIVE: To evaluate the risk factors for the development of acute renal failure (ARF) in severe rhabdomyolysis. DESIGN: Observational historical cohort study. SETTING: General intensive care unit of a university hospital. PATIENTS: Twenty-six patients with severe rhabdomyolysis, who were admitted between July 1996 and July 2001. MEASUREMENTS AND RESULTS: Clinical and laboratory data were reviewed and groups were stratified according to presence or absence of acute renal failure. The underlying cause of rhabdomyolysis was ischemia by vascular obstruction (50%), crush injury by trauma (23%), sepsis (11.5%), heatstroke/hyperthermia (11.5%) and hyponatremia in a single patient. Mean creatine kinase (CK) level was 38,351+/-35,354 U/l on admission and rose further in all patients (mean: 59,747+/-67,514 U/l). Renal failure developed in 17 patients (65%). Serum CK levels correlated with onset of ARF, as these patients had significantly higher admission and peak serum CK concentrations. Patients with ARF had a higher mortality (59% vs 22%). CONCLUSION: In our cohort of patients with severe rhabdomyolysis the level of serum CK predicted the development of ARF. Although our results suggest that series of CK determination might be beneficial for the evaluation of the effect of therapy, the value of CK determination as a prognostic tool is limited, given the wide range of CK levels.

Unanticipated error in HbA(1c) measurement on the HLC-723 G7 analyzer.

OBJECTIVES: Investigation of falsely elevated HbA(1c) measurements on the HLC-723 G7 analyser. DESIGN AND METHODS: Comparison of HbA(1c) in blood samples that were diluted either in hemolysis reagent or water. RESULTS: HbA(1c) results became falsely elevated when samples were diluted in hemolysis reagent, but not in water. QC-procedures failed to detect this error as calibrator and QC samples were manually diluted in water, according to manufacturer's instructions, whereas patient samples were automatically diluted using hemolysing reagent. After replacement of the instruments' sample-loop and rotor seal comparable HbA(1c) results were obtained, irrespective of dilution with hemolysing reagent or water. CONCLUSION: This case illustrates the importance of treating calibrator and QC materials similar to routine patient samples in order to prevent unnoticed drift in patient HbA(1c) results.

Automated flagging influences the inconsistency and bias of band cell and atypical lymphocyte morphological differentials.

This study evaluated inter- and intra-observer variabilities of band cell and atypical lymphocyte differentials and the influence of instrument flagging information on resulting microscopic differentials. Five stained slides with a range of band cell counts and five with variable numbers of atypical lymphocytes were sent for morphological review by 30 technicians. No supplementary full blood cell count information was provided. Two months later, the same slides were sent, together with their corresponding analyzer reports comprising the full blood cell count, automated differentials and flags, to the same technicians. The first and second appraisals of band cells and variant lymphocytes both showed poor levels of inter-observer consistency. Observed values for all slides were very wide and suggested a high inherent predisposition to erroneous reporting practices. Analysis of category trends showed that analyzer left shift or immature granulocytes flags had no influence on observer band cell assessments as downward vs. upward category revisions were evenly balanced. The findings for atypical lymphocytes were, however, somewhat different. Two slides with no flags both showed balanced category revisions, whereas two of the three slides with atypical lymphocyte flags showed clear evidence of upward category revision. The third slide with an atypical lymphocyte flag did not show any overall category trend, but six of the seven observers who in the first examination recorded atypical lymphocyte estimates of < or = 30% revised their estimates upward when the slides were examined the second time. These results suggest that morphologist access to an analyzer report and flagging information is unlikely to affect the "randomness" of band cell determinations but it may induce observer bias in variant lymphocyte estimates.