Unified Sigma-Metric Computation for Clinical Diagnostics

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Solution Overview

Problem

Current methods for determining the sigma-metric in clinical diagnostic processes assume homoscedasticity, which is rarely true, leading to multiple sigmas for a single process and uncertainty about which sigma is correct, making it difficult to accurately assess error tolerance and quality control.

Innovation Solution

A computer-implemented method and system that acquire specimen data from laboratory instruments, determine analytical standard deviations, assign standard deviations to patient analyte values based on corresponding concentrations, and compute a single sigma-metric by calculating the ratio of Total Allowable Error to standard deviation, providing a unified sigma value for the clinical diagnostic process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional methods are used to determine sigma-metrics in clinical processes, then multiple sigmas are obtained for different concentration levels, but it becomes unclear which sigma is correct and how to use the sigma-metric

Engineering Contradiction:
Improvesigma-metric determinationVSAvoiduncertainty about correct sigma
Core Design Contradiction:
Measurement precisionVSLoss of information

Solution Approach 1:

The patent transforms the sigma-metric calculation from concentration-specific parameters to a unified metric by changing the reference frame from individual control level sigmas to a patient-level sigma that aggregates across all concentrations. This parameter transformation resolves the ambiguity by creating a single sigma value that represents overall process performance rather than isolated concentration points.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention creates a universal sigma-metric that serves multiple functions simultaneously: it evaluates process performance across all concentration levels, provides a single comparable value for different clinical processes, and maintains relevance to patient outcomes. This multi-functional metric eliminates the need to choose between multiple concentration-specific sigmas.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If separate sigmas are displayed for each level of control material, then all concentration variations are captured, but the complexity of interpretation increases and a single process quality metric is not achieved

Engineering Contradiction:
Improvequality control accuracyVSAvoidsigma interpretation complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges multiple concentration-specific sigma values into a single unified sigma-metric by combining patient data across all control levels. This consolidation maintains the reliability of quality control by incorporating all concentration variations while simplifying interpretation to a single process quality metric that reflects overall performance.

Inventive Principle:
Principle #5Merging (Combining)

3Ease of manufacture

If homoscedasticity is assumed in sigma calculation, then the calculation is simplified, but the accuracy decreases because clinical processes are rarely homoscedastic

Engineering Contradiction:
Improvesigma calculation simplicityVSAvoidsigma-metric accuracy
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

The invention introduces dynamics into the sigma-metric calculation by using patient-level data that naturally captures variation across different concentrations. Rather than assuming static homoscedasticity, the method dynamically adapts to the actual heteroscedastic nature of clinical processes through empirical patient data, achieving both accuracy and computational feasibility.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP2457091B1System and method for determining sigma of a clinical diagnostic process
Publication Date: 2020.06.03 BIO RAD LABORATORIES INC
  • EP2457091B1 patent drawingFigure 1~2
  • EP2457091B1 patent drawingFigure 3
  • EP2457091B1 patent drawingFigure 4

AI summary

A system and method for determining a sigma of a clinical diagnostic process are disclosed. Specimen data are collected from a plurality of laboratory instruments. The specimen data are evaluated to determine a concentration and an analytical standard deviation for each data point. A clinical diagnostic process is run and patient analyte values are acquired, and a standard deviation is assigned to each patient analyte value based on the standard deviation of specimen data having a corresponding concentration. A single sigma-metric is computed based on the patient analyte assigned standard deviations, the sigma- metric representing the sigma of the clinical diagnostic process. The computed sigma-metric is reported to a user or laboratory manager.