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Editorials |
Section of Biochemistry, Department of Clinical Pathology, Cleveland Clinic Foundation, Cleveland, OH 44195, Fax 216-444-4414
The design of instruments as automated workstations for the clinical laboratory has evolved steadily over the last two decades. The grouping of assays into clinical chemistry disciplines has been largely influenced by the instrumentation available, e.g., multicomponent chemistry analyzers and specialty analyzers, including analyte-specific analyzers, blood gas analyzers, nephelometers, instruments dedicated to therapeutic drug monitoring (TDM), and instruments dedicated to protein or other immunoassays. This evolution has been a synergy of needs and technologies.
The advent of managed care has led to stringent efforts to decrease the unit costs of laboratory testing and to increase productivity. Increases in efficiency in the clinical laboratory can be achieved by modifying the overall process flow and by using more-efficient technologies. These changes are assumed to decrease labor requirements and, therefore, to decrease the major component of the direct cost of testing. The use of multiple instrument types, however, even for such altruistic reasons as optimizing analytical performance, can create a process and scheduling problem in attempts to reduce unit costs (1)(2). Each instrument utilized in a clinical chemistry laboratory (or in a multidiscipline automated core laboratory) incurs support costs: for calibration, regulation compliance, utilities, maintenance (including service contracts), computer interfacing, and inventory control, among others. These costs will exist if the front and back ends of the specimen-processing functions are completely automated. Therefore, even if all specimen manipulations are automated, reducing the number of instrument workstations can still reduce costs.
The report by Scholer et al. in this issue of Clinical Chemistry describes an immunoturbidimetric method for digoxin that requires no pretreatment (3). The assay is adaptable to general chemistry analyzers, and its performance at several different centers with a variety of instrumentation is well documented here (3). Considering the analytical requirements for an acceptable assay for serum digoxin, the performance of this assay is impressive. The routine measurement of a therapeutic drug in the micrograms per liter concentration range with the same instrument workstation that provides (e.g.) high-throughput analysis of urea nitrogen would be a major step towards workstation consolidation.
Initial efforts to expand the menu of the "chemistry profile" analyzer reflect an attempt to screen for multiple diseases, particularly thyroid disease or hemochromatosis (4). At the end of the last decade, reviews of the status of laboratory automation indicated the need for overall consolidation of instrument workstations (5). Because the clinical chemistry instrumentation at that time tended to be selected by an interesting set of mutually exclusive criteria—throughput, test menu, assay type, assay performance, and detection method—it is not yet clear whether that goal has been achieved.
Much of the testing traditionally performed on more-dedicated analyzers has been immunoassays for therapeutic drugs and serum proteins. In 1995, the Therapeutic Drug Monitoring Series I of the College of American Pathologists showed that 86% of reporting laboratories were using dedicated immunoassay analyzers to assay digoxin and, indeed, 29% were using one specific analyzer. Similarly, 87% of the laboratories reporting values for transferrin were using dedicated immunoassay analyzers and 68% were using one specific instrument. These analyzers were optimized for the necessary assay performance characteristics. Nonetheless, the flexibility of immunoassay design means that a wide variety of analytical approaches are possible and have been proven effective (6).
The application of a hapten or macromolecular immunoassay to a general chemistry analyzer with spectrophotometric and ion-selective electrode detection capabilities obviously requires a homogeneous approach. In fact, this would also be the case if fluorometric or nephelometric measurements were possible, as with some centrifugal analyzers. These assays include enzyme immunoassays, turbidimetric immunoassays, and turbidimetric inhibition immunoassays. The requirements of general random-access analyzers place defined demands on the design of immunoassays: Acceptable assay performance must be achieved, including appropriate limits of detection, specificity, reportable range, and precision. With current instrumentation, however, it is clear that this approach has limitations. Adaptations of immunoassays for most analytes to generic analyzers are unlikely to be available in the near future, although methodologies that use more-exotic detection labels and the associated automated instruments have allowed the development of immunoassays with exceptional sensitivities (7). Relatively small analytes such as thyroxine and drugs are particularly adaptable to random-access chemistry analyzers by utilizing competitive binding techniques. In contrast, those molecules such as thyrotropin, whose size and concentrations require immunometric assays, have not been successfully measured with these instruments. Nonetheless, by using the labels described above, many assays related to the disciplines of TDM and serum proteins can be adapted for use with random-access mainstream analyzers.
The scheduling of tests among several workstations within a laboratory that has been organized according to subspecialties (TDM, toxicology, proteins, endocrinology, or RIAs) has clear associated costs: e.g., the need for more sampling tubes or more aliquots, additional transport or manipulation, multiple instrument loading per specimen, and, in some cases, duplication of instrumentation and increased space requirements. More likely, organization of laboratories according to process flow will be more appropriate and more cost efficient than organization according to subspecialty. Automation of sample handling as well as of instrument loading and unloading can then be maximally effective. Consolidating these processes should challenge the inefficiencies of the subspecialty approach. The ability to consolidate assays for performance by the fewest number of analytical instruments can only facilitate efficiency of laboratory operations.
Of course, provision of clinical laboratory services involves more than just the analytical phase of the process. The practice of clinical chemistry also includes input on appropriate utilization of laboratory tests, appropriate sampling and transport, and interpretation of results—in addition to the applying and monitoring of assay methodology. All of these factors either directly or indirectly affect the overall cost of laboratory services—particularly for the hospital—and the cost of healthcare. Overutilization or inappropriate utilization of tests, incorrect sampling, insufficient sampling, and misinterpretation of results all lead to cost expenditures that cannot affect patients' outcomes positively. That is, the consolidation of assays associated with specific medical practices, e.g., management of congestive heart failure (digoxin) or seizure disorders (phenytoin), with more-generic assays (electrolyte panels) is unlikely to affect services adversely. In fact, a more streamlined focus on instrumentation could allow more resources to be allocated to the communication and consultation activities of the laboratory—which could have a very positive effect on patients' outcomes.
Most hospital and commercial laboratories perform TDM to some degree. Larger facilities use a variety of analytical instrumentation, including immunoassay, HPLC, and gas–liquid chromatography. The grouping of this type of testing as a subspecialty results from the unique aspects of measuring compounds (and their metabolites) administered to patients for therapeutic reasons. The nature of the instrumentation or workstations used in determining the concentrations of these analytes in serum or blood has also contributed to the development of specific interest in this area of laboratory medicine. Previous studies have verified the value of professional involvement in TDM in the maintenance of analytical performance, optimization of test utilization, and pharmacokinetic monitoring (8). None of these goals of a TDM program should be compromised by the consolidation of drug analyses into a more generalized analytical platform.
The primary advantage of the digoxin assay described by Scholer et al. (3) is that it does not require a "specialty instrument." The design of assay methodologies should continue to focus on reducing the number of instruments required in the clinical laboratory while maintaining maximal automation. Of course, this is also true for assays that still require manual analysis. For example, automated analysis is being developed even for molecular pathology testing (9). If these approaches are successful, what are the limits of workstation consolidation? Perhaps none, if instruments become more internally automated and have a modular design based on analytical considerations. Therefore, the currently separate instrument technologies that perform whole-blood counting or cellular evaluation, general chemistry analysis, immunoassays, viral markers/immunological assays, and molecular pathology could be performed with one instrument "system." In essence, the future clinical laboratory may well exist within one box. At least one instrument has already been introduced that combines the ability to perform assays based on multiple methodologies, including ion-selective electrodes, absorbance, and fluorescence polarization (10). Such an all-in-one analyzer could even decrease the need for postprocessing laboratory automation. Only an automated specimen-processing unit would have to be added to complete the laboratory operation.
The consolidation of laboratory workstations goes beyond just the consolidation of clinical chemistry subspecialties and often entails the formation of "core" laboratories, e.g., for automated chemistry, hematology, immunology, and coagulation testing. These core laboratories, of course, are very amenable to total automation. All of these changes challenge the established role of the professional laboratory scientist, pathologist, and technologists, but, as already stated, none should affect adversely the provision of laboratory services; instead, they are likely to improve these services. Therefore, the professionals associated with the laboratory will need to be flexible and willing to accept challenges and responsibilities beyond traditional specialty and subspecialty boundaries. These responsibilities will include necessarily the balance of economic and technological considerations. Providing scientific and clinical support by using multidisciplinary analytical technologies that improve patients' outcomes and reduce costs is the future of the clinical laboratory.
References
The following articles in journals at HighWire Press have cited this article:
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  F. Van Lente and V. Gatautis Cost-efficient Use of Gas Chromatography–Mass Spectrometry: A ""Piggyback"" Method for Analysis of Gabapentin Clin. Chem., September 1, 1998; 44(9): 2044 - 2045. [Full Text] [PDF]
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