Validation, diagnostic procedures

These are instruments developed to identify specific psychiatric disorders. Most of these scales are based on a structured or semi-structured interview lasting some 60 90 min. Structured interviews contain a mix of open-ended and closed questions. Open-ended questions are essential for the validity of a diagnostic procedure closed questions support the reliability and the standardization of diagnostic tools. The primary goal for the use of diagnostic scales is to reduce the variance within samples caused by diagnostic differences, i.e. to create homogeneous patient populations included in clinical trials. 

A great number of liver tests are nonspecific, and their results are pathological in other diseases as well. It is therefore necessary to consider the specificity, sensitivity and clinical validity of the respective tests when setting up the diagnostic procedure. 

Radioactive tracers used in medicine today provide information, and need to be judged by how reliably they provide this information. Some of the safeguards built into the drug review process by the FDA for regulating pharmaceuticals are not needed in the case of the mass of injected material used in radiopharmaceuticals. With radiopharmaceuticals, the criterion should be whether the information provided by the diagnostic procedure is valid and valuable. 

Another problem with CA is associated with diagnostics. Even if CA correctly determined the number of latent groups, this is not a guarantee that it also accurately determined group membership. Unfortunately, there are no adequate ways to assess the validity of CA group assignment. Empirical evaluation of a variety of CA methods suggests that CA procedures are actu-... 

The specimen will be the basis for the analytic analysis. Is it RNA or DNA What is the origin of the tissue Amniocentesis Was it a spontaneous product of conception Were anatomic pathology slides or tissue blocks prepared Are cell lines involved Are these primary or immortalized Was a chorionic villus sampling procedure done Is the sample properly collected peripheral blood The answers to each of these questions should be noted, and considered part of the validation of a useful nucleic acid extraction method. A molecular diagnostics laboratory should adhere to the highest standards in providing services, and prior validation of applicable nucleic acid extraction procedures is a must to ensure high-quality service. 

Qass A SIMCA Model Validation—Values (Model and Sample Diagnostic) The most direct procedure for performance evaluation of the SIMCA models is to examine how well the models classified the samrics fn m. riJ of... 

Root Mean Square EtTor of Prediction (RMSEP) Plot (Model Diagnostic) The number of variables to include is finalized using a validation procedure that accounts for predictive ability. There are two approaches for calculating the prediction error internal cross-validation (e.g., Icave-one-out cross-validation with the calibration data) or external validation (i.e.. perform prediction... 

The trend is toward friendly, increasingly miniaturized instruments that can produce efficient and selective separations. Many instruments are controlled by insertable PC cards so the analyst can automatically set up the desired procedure. Moreover, diagnostic software is helping the user to identify failures. Costs are minimized, especially solvent costs. Optimization procedures currently in use save time (and time is money). Methods and instruments are validated for compliance with, for example, ISO recommendations. 

GMP risk assessment Qualified/trained resource System life-cycle validation System environment Current specifications Software quality assurance Formal testing/acceptance Data entry authorization Data plausibility checks Communication diagnostics Access security Batch release authority Formal procedures/contracts Change control Electronic data hardcopy Secure data storage Contingency/recovery plans Maintenance plans/records... 

The complete traceability chain as presented here is valid only for those measurable quantities, which can have a value, expressed in SI units. When primary or secondary calibrators are not available the traceability chain for many measurands in laboratory medicine ends at a lower level, e.g. at the manufacturer s standing measurement procedure. In a situation where a manufacturer detects a new diagnostic marker and defines the measurable quantity by establishing a measurement procedure for this marker, the manufacturer s measurement procedure will form the top of the traceability chain. Nevertheless even in this simple situation the principles of the traceability concept are applicable. 

Once a valid calibration has been established, the calibration curve is stored in computer memory for ongoing usage. Modern NIR instmments are highly stable with respect to sensitivity drift, and extensive calibration and diagnostic test procedures have been developed which may be routinely applied to ensure this... 

Tab. 7.3 Indications for liver biopsy - unless definitive validation is possible by other procedures. The diagnostic significance of an indication is different in each individual case and can be categorized in steps ranging from of little significance through to "very important or absolutely necessary ...

Out-of-laboratory measurements are undertaken across a broad range of industrial and analytical sectors for a variety of reasons in clinical and medical diagnostics for the control of chemical and petrochemical production processes and to monitor emissions and discharges to the environment. The validity of data derived from such measurements is clearly of vital importance, for example to demonstrate compliance with environmental legislation. However, it is particularly difficult to obtain valid and reliable measurements outside the laboratory. The inability to control the environment in which the measurements are made and the use of untrained operators both have potential to impact significantly on the reliability of data. The situation is made worse because of the lack of adequate QA and QC procedures, the shortage of reference materials and calibration standards, and... 

Community on In-Vitro Diagnostics) is a European legislative regulation directed at in vitro manufacturers. The directive demands that the manufacturer have a quality management system and that products are validated by competent laboratories. It is required that the traceability of values assigned to calibrators or control materials or both must be ensured through available reference measurement procedures and/or available materials of higher order. Explicit statement of the uncertainty of calibrator values is not required, but indirectly the manufacturers have to... 

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