The discordance rate, a new concept for combining diagnostic decisions with analytical performance characteristics. 2. Defining analytical goals applied to the diagnosis of type 2 diabetes by blood glucose concentrations

Abstract

AbstractA novel statistical approach has recently been described to estimate diagnostic “errors” in method comparison studies. This procedure requires a population-based probability, pThe new concept was then applied in a reverse mode by determining the analytical variability of glucose concentrations for a fixed discordance rate diagnosing type 2 diabetes. If a combined discordance rate (sum of positive and negative discordances) of 5% is allowed, a maximal imprecision of 3.7% can be tolerated in the absence of bias. In the presence of a 3.0% bias, the allowable imprecision must be reduced to 2.8%. The relationship between bias and imprecision followed a complex function and not a simple linear model. These allowable limits were achieved with venous plasma in the fasting state.The allowable analytical specifications were slightly more stringent with capillary blood. After a 2 h glucose challenge, higher error rates could be tolerated, indicating that post-load glucose concentrations have a higher diagnostic efficiency than fasting levels. The new concept has the advantage that it is derived from patient's samples in relation to diagnostic requirements.