Reference Change Value Concept Combining Two Delta Values to Predict Crises in Renal Posttransplantation

Abstract

The concept of reference change value (RCV) was developed by Harris and Yasaka (1)(2) to identify significant changes in the state of patients when monitoring their pathology. This concept can be applied to the laboratory data routinely acquired for renal posttransplantation patients to detect potential crises before clinical indications are manifested. The RCV takes into account the within-subject biological variation as well as the analytical (3)(4)(5)(6)(7) when: In previous work using data from kidney transplantation patients (6)(8), we noted that the analytes most suitable for detecting significant changes during posttransplantation follow-up are serum creatinine, urate, and urea. We hypothesized that the predictive power of these analytes might greatly increase if more than one showed simultaneous and independent changes before the clinical manifestations of reduced kidney function became apparent. We developed an objective analytical indicator (using these analytes) to detect potential subclinical crises in renal transplant recipients based on the RCV concept. To make the model relevant for use in daily practice, we attempted to include nephrologists’ criteria in the final values proposed by determining the factors they consider crucial when monitoring their transplant patients (9)(10). The underlying goal of this effort was to extract the most information possible from routine laboratory data and offer the clinician an improved tool for patient care. To test whether the concentrations of creatinine, urea, and urate were independent, pairs of data from the three quantities in the same individuals and the same …