Value assignment for customizable quality controls
Methods are provided for end users of diagnostic measurement procedures to prepare quality controls having desired analyte recoveries, estimate recoveries of quality controls already prepared, and compare estimated and measured recoveries. To prepare a quality control containing a particular analyte, a desired recovery of a measurement procedure for the analyte can be scaled by a correlation factor to obtain a target nominal concentration of the analyte in the quality control. Alternatively, the nominal concentration of an analyte in a quality control can be scaled by a correlation factor to obtain a predicted recovery of a measurement procedure for the analyte. The correlation factors can be based on recovery data previously obtained using the measurement procedure and optionally one or more reference procedures, and can be calculated using regression analysis of these data. Each quality control can be prepared by dissolving a number of solid beads containing the analyte(s) of interest in a volume of base matrix.
1. A method of preparing a quality control for an analyte, the method comprising:
applying a function to a desired reported concentration of an analyte in a quality control to return a target concentration of the analyte in the quality control, wherein the desired reported concentration is a concentration value desired to be obtained from a measurement procedure, wherein the measurement procedure is a technique or system for detecting a concentration of an analyte, and wherein the function is derived by applying regression analysis to analyte concentration data previously obtained using the measurement procedure;
providing one or more solid beads containing the analyte, and a base matrix, wherein the solid beads are water-soluble spheres or pellets, and wherein the base matrix is a material substantially devoid of the analyte;
determining a number of solid beads and a volume of the base matrix needed to prepare the quality control with the target concentration of the analyte; and
dissolving the number of beads in the volume of the base matrix, thereby preparing the quality control for the analyte.
2. The method of claim 1 , further comprising:
designating one or more nearby reported analyte concentrations, wherein each nearby reported analyte concentration is at least 10% above or below the desired reported concentration of the analyte in the quality control; and
estimating, using the function, concentrations of the analyte in one or more nearby quality controls corresponding to the one or more nearby reported analyte concentrations.
3. The method of claim 1 , wherein the applying of the function returns a reference reported concentration of the analyte in the quality control, wherein the reference reported concentration is a concentration value obtained from a reference measurement procedure for the analyte, and wherein the function is derived by applying regression analysis to analyte concentration data previously obtained using the measurement procedure and the reference measurement procedure.
4. The method of claim 3 , further comprising:
designating one or more nearby reference reported analyte concentrations, wherein each nearby reference reported concentration of the analyte in the quality control is at least 10% above or below the reference reported concentration of the analyte in the quality control; and
estimating, using the function, concentrations of the analyte in one or more quality controls corresponding to the nearby reference reported analyte concentrations.
5. The method of claim 1 , wherein the applying of regression analysis comprises fitting a regression line to a plot of analyte concentration data previously obtained using the measurement procedure versus previous analyte concentrations.
6. A method of evaluating a predicted reported concentration of an analyte in a quality control as reported by a measurement procedure for the analyte, the method comprising:
preparing a quality control having a concentration of the analyte;
applying a function to the concentration of the analyte in the quality control to return a predicted reported concentration of the analyte in the quality control as reported by a measurement procedure, wherein the measurement procedure is a technique or system for detecting the concentration of the analyte, and wherein the function is derived by applying regression analysis to analyte concentration data previously obtained using the measurement procedure;
testing the quality control using the measurement procedure, thereby obtaining a measurement response;
determining an actual reported concentration of the measurement procedure for the analyte based on the measurement response;
comparing the predicted reported concentration with the actual reported concentration, thereby evaluating the predicted reported concentration of the analyte in the quality control as reported by the measurement procedure for the analyte.
7. The method of claim 6 , wherein preparing the quality control comprises adding a number of solid beads containing the analyte to a volume of a base matrix, wherein the solid beads are water soluble spheres or pellets, wherein the base matrix is a material substantially devoid of the analyte, and wherein the concentration of the analyte in the quality control is determined based on the number of beads and the volume of the base matrix.
8. The method of any one of claims 1 - 4 and 7 , wherein the base matrix is obtained from one or more patient samples.
9. The method of claim 6 , further comprising designating one or more nearby concentrations of the analyte, wherein each nearby concentration is at least 10% above or below the concentration of the analyte in the quality control; and
obtaining, using the function, one or more predicted reported concentrations of the analyte corresponding to the one or more nearby concentrations of the analyte.
10. The method of claim 6 , further comprising:
obtaining a range of reported concentrations of the analyte as reported by the measurement procedure for the analyte, wherein the range contains the predicted reported concentration of the analyte.
11. The method of claim 6 , wherein the applying of the function converts a reference reported concentration to the predicted reported concentration of the analyte in the quality control as reported by the measurement procedure, wherein the reference reported concentration is a concentration value obtained from a reference measurement procedure for the analyte at the concentration of the analyte in the quality control, and wherein the function is derived by applying regression analysis to analyte concentration data previously obtained using the measurement procedure and the reference measurement procedure.
12. The method of claim 6 , wherein the applying of regression analysis comprises fitting a regression line to a plot of analyte concentration data previously obtained using the measurement procedure versus previous analyte concentrations.