College of American Pathologists 2003 fresh frozen serum proficiency testing studies

Revised system to evaluate measurement of blood chemistry data from the Japanese National Health and Nutrition Survey and Prefectural Health and Nutrition Surveys

BACKGROUND

We developed a monitoring system that uses total errors (TEs) to evaluate measurement of blood chemistry data from the National Health and Nutrition Survey (NHNS) and Prefectural Health and Nutrition Surveys (PHNS).

METHODS

Blood chemistry data from the NHNS and PHNS were analyzed by SRL, Inc., a commercial laboratory in Tokyo, Japan. Using accuracy and precision from external and internal quality controls, TEs were calculated for 14 blood chemistry items during the period 1999-2010. The acceptable range was defined as less than the upper 80% confidence limit for the median, the unacceptable range as more than twice the cut-off value of the acceptable range, and the borderline range as the interval between the acceptable and unacceptable ranges.

RESULTS

The TE upper limit for the acceptable and borderline ranges was 5.7% for total cholesterol (mg/dL), 9.9% for high-density lipoprotein cholesterol (mg/dL), 10.0% for low-density lipoprotein cholesterol (mg/dL), 10.4% for triglycerides (mg/dL), 6.6% for total protein (g/dL), 7.6% for albumin (g/dL), 10.8% for creatinine (mg/dL), 6.5% for glucose (mg/dL), 9.7% for γ-glutamyl transpeptidase (U/L), 7.7% for uric acid (mg/dL), 8.7% for urea nitrogen (mg/dL), 9.2% for aspartate aminotransferase (U/L), 9.5% for alanine aminotransferase (U/L), and 6.5% for hemoglobin A1c (%).

CONCLUSIONS

This monitoring system was established to assist health professionals in evaluating the continuity and comparability of NHNS and PHNS blood chemistry data among survey years and areas and to prevent biased or incorrect conclusions.

Status of serum-calcium and -albumin measurement in Argentina assessed in 300 representative laboratories with 20 fresh frozen single donation sera

BACKGROUND

The Fundación Bioquímica Argentina (FBA) performs external quality assessment (EQA) of >3200 laboratories. However, FBA realizes that sample non-commutability and predominant use of heterogeneous systems may bias the estimated performance and standardization status. To eliminate these confounding factors, a study using frozen single donation sera was undertaken with the focus on serum-calcium and -albumin measurement.

METHODS

Target values were established from the results produced with homogeneous systems. In groups of n=7, system effects were investigated. Laboratory performance was evaluated from the correlation coefficient r between the measurement results for all sera and the target values. This allowed ranking of the laboratories and judgment of the deviation for individual samples (total error) against a 10% limit. The total error specification was a deviation for ≥ 5 samples exceeding 10% and/or causing a result outside the laboratory's reference interval.

RESULTS

For calcium (n=303) (range: 2.06-2.42 mmol/L), 81 laboratories had an r-value <0.6, 43 even <0.4; the total error was relevant for 97 (10% limit) and 111 (reference interval) laboratories. For albumin (n=311) (range: 34.7-45.7 g/L) r was <0.7 (<0.4) in 44 (16) laboratories; 83 and 36 laboratories exceeded the total error criteria. Laboratories using homogeneous systems were generally ranked higher by correlation. System effects were moderate for calcium, but significant for albumin.

CONCLUSIONS

The study demonstrated the need to improve the quality and harmonization of calcium and albumin testing in the investigated laboratories. To achieve this objective, we promote co-operation between laboratories, EQA provider and manufacturers.

Laboratory sanctions for proficiency testing sample referral and result communication: a review of actions from 1993-2006

CONTEXT

The Clinical Laboratory Improvement Amendments of 1988 (CLIA) regulations for proficiency testing (PT) include prohibitions against intentional PT sample referral or result communication, and specify sanctions against laboratories that violate these regulations. There has been little published analysis of sanctions against clinical laboratories because of PT violations.

OBJECTIVE

To examine the application of principal sanctions as reported by the Centers for Medicare and Medicaid Services annually in the Laboratory Registry and to examine relevant aspects of judicial hearings and appeals in these cases.

DESIGN

The Laboratory Registry was examined for all available years (1993-2006) to determine the incidence of application of principal sanctions for PT violations. In addition, the decisions from the US Department of Health and Human Services hearings and appeals were reviewed to better understand the judicial disposition of these cases.

RESULTS

During the 14-year period examined, 78 laboratories received a principal sanction for a PT violation involving sample referral or result communication. During the same period, the number of laboratories in nonexempt states that would be expected to have participated in PT averaged 45 983. The interpretive meaning of the key terms intentional and referral, and the implications for sanctioned laboratories and their owners and operators are discussed.

CONCLUSIONS

Applications of a principal sanction for a PT violation were rare during the period of this study. However, the consequences of the imposition of such a sanction are severe. Suggestions are offered on policies and practices to minimize the risk of a PT sample referral or result communication.

Establishment of long-term monitoring system for blood chemistry data by the national health and nutrition survey in Japan

AIM

We established a monitoring system for the annual follow-up of blood chemistry data obtained by the National Health and Nutrition Survey in Japan.

METHODS

Blood chemistry testing has been entrusted to SRL Inc. We used two external quality control assurance programs established by the Japan Medical Association (JMA) and by CDC/CRMLN during the previous 8-year period. Ten analytes were measured: total cholesterol, HDL cholesterol, triglycerides, urea nitrogen, uric acid, creatinine, AST (GOT), ALT (GPT), gamma-GT (gamma-GTP), and glucose. Total error (TE) was calculated from accuracy by the JMA program and precision by internal quality control of SRL. The permissible range of TE values was determined to be 50% of the evaluation limit on one side in the evaluation criteria of the College of American Pathologists (CAP). When TE fell within the permissible range, the follow-up of annual changes was considered possible.

RESULTS

Annual follow-up of blood chemistry data was considered possible for all the analytes except urea nitrogen. Based on this study, new permissible TE ranges are proposed.

CONCLUSION

We confirmed the functioning of the monitoring system for the annual follow-up of blood chemistry data obtained by the National Health and Nutrition Survey in Japan.

The origin of reference intervals

CONTEXT

Standards have been developed for establishing reference intervals, but little is known about how intervals are determined in practice, interlaboratory variation in intervals, or errors that occur while setting reference intervals.

OBJECTIVES

To determine (1) methods used by clinical laboratories to establish reference intervals for 7 common analytes, (2) variation in intervals, and (3) factors that contribute to establishment of "outlier" intervals.

DESIGN

One hundred sixty-three clinical laboratories provided information about their reference intervals for potassium, calcium, magnesium, thyroid-stimulating hormone, hemoglobin, platelet count, and activated partial thromboplastin time.

RESULTS

Approximately half the laboratories reported conducting an internal study of healthy individuals to validate reference intervals for adults. Most laboratories relied on external sources to establish reference intervals for pediatric patients. There was slight variation in intervals used by the central 80% of study laboratories, but some laboratories outside the central 80% had surprisingly low and high limits for their reference intervals. In some cases the intervals used by 2 laboratories had no overlap. For example, one laboratory considered a hemoglobin of 13.8 g/dL in a woman to be "low" while another considered the same value to be "high." Three percent of reference intervals contained a limit that qualified as an "outlier" using standard statistical tests; we could not identify any practice associated with adoption of outlier intervals.

CONCLUSIONS

Many laboratories adopt reference intervals from manufacturers without on-site testing of healthy individuals. Reference intervals used by facilities that forgo on-site testing are not statistically different from intervals validated with on-site studies.