Performance characteristics of a blood cholesterol measuring instrument used in screening programs

Four experiments were conducted to assess the precision and accuracy of the Boehringer Mannheim Diagnostics Reflotron, an instrument that is being adopted by many public health groups to conduct blood cholesterol screening programs. Our study is one of the first to evaluate and document the instrument's performance characteristics. Successive generations of reagent tabs supplied by the manufacturer were tested against a reference laboratory method standardized by the Centers for Disease Control. Three of the experiments also compared two or more Reflotrons to assess intermachine reliability. The Reflotron analyzer provided precise blood cholesterol measurements both in repeated tests and among instruments. The accuracy of the method varied across reagent lots, with an average negative bias of 21.05 milligrams per deciliter (mg per dl), decreasing steadily to a negative bias of 4.07 mg per dl. Reliability between and within analyzers was high. The data provide support for the use of the instrument in blood cholesterol screening efforts, yet signal the need for attention to quality control procedures, both by the manufacturer and operators, to ensure the validity and accuracy of the results.