Sigma Metrics used to Evaluate the Performance of Internal Quality Control in a Clinical Biochemistry Laboratory.

BACKGROUND: The performance of 17 routine chemical detection methods was evaluated by the Sigma (σ) index, and separate quality control standards were established according to the sigma values of different detection methods. METHODS: The internal quality control (IQC) and external quality assessment (EQA) data of 17 assays in the biochemical laboratory of our hospital were collected from January to June 2019. Referring to the total allowed error (TEa) standards established in the Health Industry Standards of the People's Republic of China (WS/T 403-2012), the sigma metric of each assay was calculated, the performance level for inspection was evaluated, the quality goal index (QGI) was calculated for items with analysis performance < 5 sigma, and the main causes of poor performance were determined to guide quality improvement. RESULTS: For level 1 internal quality control (IQC), five assays (AMY, Crea, UA, TP, and Na) showed a performance of ≥ 6 sigma levels. Five assays (GGT, LDH, ALP, K, and Ca) had a performance lower than 3 sigma. For level 2 IQC, nine assays (ALT, AST, CK, AMY, Crea, UA, TP, Na, and Mg) achieved 6 sigma, and four assays (GGT, LDH, ALP, and K) achieved less than 3 sigma. Among the 12 assays with a sigma value < 5, the precision of 1 assay should be improved first, the accuracy of 6 assays should be improved next, and both the precision and the accuracy of 5 assays should be improved. CONCLUSIONS: The sigma metric is the best tool for evaluating the performance of different test methods. Assays with high sigma values can be evaluated with single-rule quality control, while assays with low values should be evaluated with strict quality control rules.

The C-Reactive Protein/Albumin Ratio as a Predictor of Mortality in Patients with HBV-Related Decompensated Cirrhosis.

BACKGROUND: The C-reactive protein to albumin ratio (CAR) is a novel inflammation index that has recently been used as a marker for poor prognosis or mortality in various patient groups. This study aimed to evaluate the association between the CAR and 30-day mortality in patients with hepatitis B virus-related decompensated cirrhosis (HBV-DeCi). METHODS: This was a retrospective cohort study of 113 patients who had been diagnosed with HBV-DeCi. Univariate and multivariate regression models were used to determine risk factors for mortality. RESULTS: The CAR was observed to be significantly higher in the non-surviving patients compared to the surviving patients. Moreover, the CAR was positively correlated with the model for end-stage liver disease (MELD) score and Child-Pugh score. In multivariate analysis, the CAR and the MELD score were independent prognostic factors for HBV-DeCi patients. CONCLUSIONS: A high CAR value at admission can serve as an independent predictor of 1-month mortality in patients with HBV-DeCi.