Lack of transferability between two automated immunoassays for serum IGF-I measurement.

BACKGROUND: IGF-I is a clinically relevant protein in the diagnosis and monitoring of treatment of growth disor- ders. The Growth Hormone Research Society and the International IGF Research Society have encouraged the adoption of a universal calibration for immunoassays to improve standardization of IGF-I measurements, but currently commercial assays are calibrated either against the old WHO IRR 87/518 or the new WHO 02/254. We compared two IGF-I immunochemiluminescent assays: IMMULITE® 2000 (Siemens) and LIAISON® (DiaSorin), which differ in their standardization, and verified their precision according to quality specifications based on biological variation and their linear range. METHODS: 62 patient serum samples were analyzed for both assays and compared according to standards of the Clinical and Laboratory Standards Institute (CLSI), EP9-A2-IR. Precision was verified according to CLSI EP15- A2. Optimal coefficient of variation (CVo) and desirable coefficient of variation (CVd) for IGF-I assays were calculated as quality specifications based on the biological variability, in order to assess if the interassay analytical CV (CVa1) in the two methods were appropriate. Two dilution series using the 1st WHO International Standard (WHO IS) for IGF-I 02/254 were used to verify and compare the linearity range. RESULTS: The regression analysis showed constant and proportional differences for serum samples (slope b = 0.8115 (CI 95% CI; 0.7575-0.8556); intercept a = 33.6873 (95% CI: 23.3613-44.0133) between assays and similar pro- portional differences for WHO IS 02/254 standard dilutions series (slope b = 0.8024 (CI 95% CI; 0.7560-0.8616); intercept a = 6.9623 (95% CI: -2.0819-18.4383) between assays. Within-laboratory coefficients of variation for low and high levels were 2.82% and 3.80% for IMMULITE® 2000 and 3.58% and 2.14% for LIAISON®, respecttively. CONCLUSIONS: IGF-I concentrations measured by both assays are not transferable. The results emphasize the need to express IGF-I concentrations in standard deviation score (SDS) according to a matched normal population of the same age and gender. Within-laboratory precision in both methods met quality specifications derived from biological variation.

Quality indicators and specifications for key analytical-extranalytical processes in the clinical laboratory. Five years' experience using the Six Sigma concept.

BACKGROUND: The results of 5 years of experience (2004-2008) with process-based quality management using quality indicators for key laboratory processes (analytic and extra-analytic) in a group of clinical laboratories affiliated with the Catalan Health Institute are presented. Our purpose was to analyze the evolution of the indicators, identify processes that require corrective measures, and obtain specifications that are more robust than the preliminary ones proposed in a previous study by the same group. METHODS: The yearly average was recorded for each indicator in each laboratory, the yearly interlaboratory median was calculated, and the changes occurring were studied to determine their continuity in the 5-year period. For each indicator, the average of the yearly medians was calculated and the results transformed to the Six Sigma scale to estimate the degree of control over the related process. It was suggested to establish the yearly interlaboratory median as the desirable specification for each indicator. RESULTS: The medians for most indicators were stable during the period studied. Thus, the specifications proposed in the first study were considered robust in these cases. The Six Sigma statistic provided added value in this study because it enabled detection of processes that should be improved, in which case the specifications proposed were considered provisional despite their stability. After identifying processes that have the greatest impact on patient safety, the group set a specification of 0%, regardless of the actual specification obtained, although the members are conscious of the difficulty in attaining this level of quality. Certain processes that are in a period of change obtained specifications that are considered in a phase of consolidation. CONCLUSIONS: The results for indicators related with sample collection indicate that the process is stable and well controlled. However, based on the results for Hemolyzed serum sample, the group saw the need for installing centrifuges in all phlebotomy centers and established a recommendation to unify the system for measuring hemolysis. The indicator External control exceeds acceptance limit clearly highlighted the need to rigorously monitor the analytic phase of the clinical laboratory. The values obtained for the indicator Reports from referred tests exceed delivery time show that there is considerable deviation regarding the expected report delivery time, whereas for in-house laboratory reports, delivery time is satisfactory.

Indicators and quality specifications for strategic and support processes related to the clinical laboratory: four years' experience.

BACKGROUND: Quality specifications for indicators of the key analytic processes have been defined by international consensus. However, only preliminary specifications for laboratory-related strategic and support processes have been developed. The present study attempts to increase the robustness of the preliminary proposed specifications. METHODS: Recovering records and incidences occurred over a 4-year follow-up period, for 12 indicators, used in all laboratories from this group regarding strategic and support processes. RESULTS AND CONCLUSIONS: The results obtained indicate that it is better to establish an interval rather than a fixed value for the majority of indicators. Longer studies are needed to properly assess some quality specifications, and data recording system must be standardized in others. Additional, multicenter studies are needed to establish more robust specifications and determine the state of the art of laboratories in other settings.

Quality indicators and specifications for strategic and support processes in laboratory medicine.

BACKGROUND: This work is the second part of a study regarding indicators and quality specifications for the non-analytical processes in laboratory medicine. Five primary care and five hospital laboratories agreed on the indicators for two strategic processes (quality planning and project development) and various support processes (client relationships, instrument and infrastructure maintenance, safety and risk prevention, purchases and storage, personnel training). METHODS: In the majority of cases, the median values recorded over 1 year is considered to be the state-of-the-art in our setting and proposed as the quality specification for the indicators stated. Values have been stratified according to primary care and hospital laboratory for referred tests and group of personnel for training. In some cases, the specifications have been set equal to zero events, such as serious incidents in the infrastructure maintenance process and number of work accidents in the safety and risk prevention process. RESULTS AND CONCLUSIONS: In light of this study, an effort is needed to optimize decisions regarding corrective actions and to move from a subjective individual criterion to systematic and comparative management. This preliminary study provides a comprehensive vision of a subject that could motivate further research and advances in the quality of laboratory services.