• Report

The Impact of Calibration Error in Medical Decision Making

Citation

Gallaher, M., & Mobley, L. (2004). The Impact of Calibration Error in Medical Decision Making. Unknown Publisher.

Abstract

Consensus guidelines and disease management strategies have standardized the medical approach to many common disorders. Unfortunately, the developers of medical guidelines have assumed that all laboratories function well and all test results are comparable. Medical guidelines seldom contain any information about the performance characteristics for key tests used in the diagnostic decision process. Guidelines typically have specific thresholds or “acceptable ranges,” such as 8.9 to 10.1 mg/dL of calcium in tests to diagnose hypercalcemia, without any reference to measurement methodology or measurement standardization. Consequently, there is a false sense of security that the health care system assures adequate quality for laboratory tests. Calibration error, leading to analytic bias, is a key parameter affecting the number of patients passing decision thresholds in practice guidelines. The Food and Drug Administration (FDA) requires that new tests perform equivalent to previously approved methods but does not require metrological traceability to reference methods. In addition, the Clinical Laboratory Improvement Amendments (CLIA) performance limits for proficiency tests are very wide, which allows large “between-lot” differences within methods and large “between-method” variations. This study investigates the potential impact on health care costs from calibration error resulting in analytic bias in tests to measure serum calcium levels. Hypercalcemia is a medical condition caused by various disorders—most commonly hyperparathyroidism and cancer. The signs and symptoms of hypercalcemia are nonspecific; therefore, the clinician is very dependent on accurate laboratory measurements for detecting and evaluating this disorder. Medical guidelines recommend that hypercalcemia be confirmed with follow-up procedures, such as intact parathyroid hormone (PTH) measurement, chest X-rays, 24-hour urinary calcium measurement, ionized calcium measurement, and thyroid imaging.