The accuracy and timeliness of a Point Of Care lactate measurement in patients with Sepsis.

BACKGROUND: The aims of this study were to a) compare the lactate measurement of a Point of Care (POC) handheld device to near patient blood gas analysers, and b) determine the differential reporting times between the analysers. METHODS: A two-staged study; method comparison and prospective observational stages, was conducted. For the first stage, blood samples were analysed on the i-STAT handheld device and the near patient blood gas analysers (GEM 4000 and OMNI S). Results were compared using Pearson correlation coefficient and Bland-Altman tests. For the second stage, we examined the differential reporting times of the POC device compared to the near patient blood gas analysers in two Scottish hospitals. Differential reporting times were assessed using Mann-Whitney test and descriptive statistics were reported with quartiles. RESULTS: Highly significant Pearson correlation coefficients (0.999 and 0.993 respectively) were found between i-STAT and GEM 4000 and OMNI S. The Bland-Altman agreement method showed bias values of -0.03 and -0.24, between i-STAT and GEM 4000 and OMNI S respectively. Median time from blood draw to i-STAT lactate results was 5 min (Q1-Q3 5-7). Median time from blood draw to GEM 4000 lactate results was 10 min (Q1-Q3 7.75-13). Median time from blood draw to OMNIS lactate results was 11 min (Q1-Q3 8-22). The i-STAT was significantly quicker than both the GEM 4000 and the OMNIS (each p-value < 0.001). In addition, 18 of our study samples were sent to the central laboratory for analysis due to a defect in the lactate module of OMNI S. The median time for these samples from blood draw to availability of the central laboratory results at the clinical area was 133 min. CONCLUSIONS: The POC handheld device produced accurate, efficient and timely lactate measurements with the potential to influence clinical decision making sooner.

Improved detection of hereditary haemochromatosis.

AIMS: There is high prevalence of hereditary haemochromatosis (HH) in North European populations, yet the diagnosis is often delayed or missed in primary care. Primary care physicians frequently request serum ferritin (SF) estimation but appear uncertain as how to investigate patients with raised SF values. Our aim was to develop a laboratory algorithm with high predictive value for the diagnosis of HH in patients from primary care with raised SF values. METHODS: Transferrin saturation (Tsat) was measured on SF samples sent from primary care; 1657 male and 2077 female patients age ≥ 30 years with SF ≥ 200 µg/L. HFE genotyping was performed on all 878 male and 867 female patients with Tsat >30%. RESULTS: This study identified 402 (206 men; 196 women) C282Y carriers and 132 (58 men; 74 women) C282Y homozygotes. Optimal limits for combined SF and Tsat values for HH recognition were established. The detection rate for homozygous C282Y HH for male patients with both SF ≥ 300 µg/L and Tsat >50% was 18.8% (52/272) and 16.3% (68/415) for female patients with both SF ≥ 200 µg/L and Tsat >40%. CONCLUSIONS: The large number of SF requests received from primary care should be used as a resource to improve the diagnosis of HH in areas of high prevalence.

Comparison of cystatin C and creatinine-based glomerular filtration rate formulas with 51Cr-EDTA clearance in patients with cirrhosis.

BACKGROUND AND OBJECTIVES: Renal function is an important predictor of survival in cirrhosis and liver transplantation. GFR estimates using serum cystatin C (CysC) are proposed as better predictors of renal function than ones on the basis of serum creatinine (Cr). Our aims were: (1) evaluate correlations between serum CysC and different methods of creatinine measurements; (2) compare CysC and Cr GFR formulas with (51)Cr-EDTA; and (3) evaluate liver-related parameters potentially influencing GFR. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: 254 blood samples in 65 patients with cirrhosis correlating CysC with four Cr methods were used; another 74 patients comparing (51)Cr-EDTA GFR to Modification of Diet in Renal Disease and Larsson and Hoek formulas for CysC were also included. Agreement was assessed using Bland-Altman plots and concordance correlation coefficients. Multivariate linear regression analysis was used for GFR predictors. RESULTS: Serum CysC correlated modestly with O'Leary modified Jaffe, compensated kinetic Jaffe, enzymatic creatinine, and standard kinetic Jaffe 0.72/0.71/0.72/0.72 (all P < 0.001). Bland-Altman agreement with (51)Cr-EDTA GFR was poor; the best agreement was Modification of Diet in Renal Disease (concordance 0.61; 95% CI, 0.47 to 0.71); the worst agreement was the Hoek formula (concordance 0.46; 95% CI, 0.27 to 0.61). A new GFR formula including the Child-Pugh score improved the accuracy of Cr GFR formulas compared with (51)Cr-EDTA GFR. CONCLUSIONS: Estimated GFR in cirrhosis is not better with CysC formulas compared with creatinine ones: specific formulas may be necessary.

Assessment of reproducibility of creatinine measurement and MELD scoring in four liver transplant units in the UK.

UNLABELLED: The Model for End-Stage Liver Disease (MELD) or similar scoring system is proposed in the UK for prioritization for liver transplantation. We evaluated the reproducibility of creatinine measurements and therefore MELD scores in four liver transplant units in the UK. METHODS: All transplant units were invited to participate; four agreed to do so, contributing 36 patients awaiting liver transplantation. Blood was collected from these 36 and divided into aliquots then sent to the four participating centres. Every centre measured creatinine and bilirubin for every patient. The results were analysed for the degree of agreement between centres for creatinine and MELD scores using the Bland-Altman method and Wilcoxon rank test. RESULTS: The mean creatinine value varied from 101 mumol/l in centre C to 110 micromol/l for the same sample in centre A, with significant differences between the four centres (P < 0.05, Wilcoxon signed-rank test). The MELD scores were significantly different between centre C and all other centres (P < 0.05). CONCLUSION: This study demonstrates lack of agreement in measurement of serum creatinine and MELD scoring between four UK transplant centres. A difference in two MELD points can have a significant impact on patient outcome, and these factors will have to be addressed if a UK-wide transplant list is to be initiated.

Different methods of creatinine measurement significantly affect MELD scores.

Bilirubin (Bil) interferes with creatinine (Cr) measurement. Different laboratory methods are used to overcome this problem. Model for end-stage liver disease (MELD) scoring incorporates Cr and is used to prioritize patients for liver transplantation. Thus, MELD scores may vary with different Cr measurements influencing patients' priority. Our aim was to evaluate 4 different Cr assays (O'Leary modified Jaffe [mJCr], compensated [rate blanked] kinetic Jaffe [cJCr], enzymatic [ECr], and standard kinetic Jaffe [JCr]) in patients with abnormal liver function tests and assess changes in MELD score. A total of 403 consecutive samples from 158 patients' Cr assays were evaluated.. Bland-Altman plots and MELD scores were also evaluated for each assay. Agreement was found to be poor among all Cr assays. Increased variability in Cr occurred with increasing Bil concentrations: Bil <100 micromol/L or=400micromol/L or=3-point difference in 78%. When MELD was >or=25 (mJCr as reference; mean, 30.5 points), MELD variation was greatest: mean, 28 (MELD cJCr), 27.5 (MELD ECr), and 28.4 (MELD JCr) (P < 0.001). In conclusion, there is poor agreement among different assays for Cr. As Bil concentration rises, there is greater variability in each creatinine measurements and thus greater variability in MELD scores that, this affect prioritization for liver transplantation.