The Basic Concepts of Quality Control Reference: Interval Studies, Diagnostic Efficiency, and Method Evaluation in Quality Control

Laboratory data are very important in making majority of the patient's decisions. Before introducing a new test to the patients, it is very important that the acceptable performance of the test is carried out. Hence, "method evaluation" should be carried out to find out and verify the accuracy of a new test before it is used in patients. Once the method has been approved, it is the job of the laboratory personnel to utilize "quality control" techniques to maintain it. All these fall under the system of "quality management." Laboratorians use the concepts of "descriptive statistics" for comparing and analyzing different data. Descriptive statistics encompasses a variety of measures. Diagnosis in the medical field and initiation and management of various therapies depend upon the comparison of the patient's test result with a "reference interval." A specified percentage of the values for a population is used to set the lower and upper reference limits. Reference interval should be established and verified before it can be used in patients. After establishing the reference interval, the analytic and pre-analytic variables must also be standardized in order to verify and make validations of that particular reference interval. There are numerous requirement establishment of a reference interval. Establishment of reference interval requires data analysis. A number of parameters are used to find out how efficient a particular test is for predicting or nullifying a particular disease. These parameters fall under the broad heading of "diagnostic efficiency." Diagnostic efficiency encompasses "predictive values," "specificity," and "sensitivity." It is very important that accurate and reliable test results are provided by the clinical laboratory service. To enable this, a method undergoes the full process of "method evaluation." "Imprecision" and "inaccuracy" are the first estimates to be made in a method evaluation; then, they are compared with the maximum allowable medical criteria-based error. Then, the use of "quality control" and "quality control charts" follows.